Efficiency potentials of heat pumps with combined heat and power. For maximum reduction of CO2 emissions and for electricity generation from fossil fuels with CO2 reduction in Switzerland

International Nuclear Information System (INIS)

Rognon, F.

2005-06-01

This comprehensive report for the Swiss Federal Office of Energy (SFOE) takes a look at how the efficiency potential of heat pumps together with combined heat and power systems can help provide a maximum reduction of CO 2 emissions and provide electricity generation from fossil fuel in Switzerland together with reductions in CO 2 emissions. In Switzerland, approximately 80% of the low-temperature heat required for space-heating and for the heating-up of hot water is produced by burning combustibles. Around a million gas and oil boilers were in use in Switzerland in 2000, and these accounted for approximately half the country's 41.1 million tonnes of CO 2 emissions. The authors state that there is a more efficient solution with lower CO 2 emissions: the heat pump. With the enormous potential of our environment it would be possible to replace half the total number of boilers in use today with heat pumps. This would be equivalent to 90 PJ p.a. of useful heat, or 500,000 systems. The power source for heat pumps should come from the substitution of electric heating systems (electric resistor-based systems) and from the replacement of boilers. This should be done by using combined heat and power systems with full heat utilisation. This means, according to the authors, that the entire required power source can be provided without the need to construct new electricity production plants. The paper examines and discusses the theoretical, technical, market and realisable potentials

Life cycle assessment of peat utilisation in Finland

International Nuclear Information System (INIS)

Maelkki, H.

1997-01-01

, however, poorly known at the moment. The Tehoturve method is today the method most commonly used in the production of milled peat, and it is gradually replacing the traditional Haku method. The Tehoturve method is environmentally better than the Haku method. The new Sod Wave method is the best method from the environmental point of view because the production time is shortest. The carbon dioxide emissions of the energy conversion phase make up the biggest share of the total carbon dioxide emissions: well over 90 % of the total amount. Combined heat and power production also gives environmentally better results than separate heat production. The results of the impact assessment mainly follow the inventory results. The airborne emissions of the energy conversion phase cause the biggest acidification and global warming effects. The water emissions of the peat production phase cause the biggest eutrophication effects. In the life cycle assessment the key factors of the peat utilization options are the definition of boundaries, the life cycle time, the restoration mode and the peat production method used. This study also shows that the assessed restoration way and time give an opportunity to evaluate peat utilisation from different aspects of sustainability. (orig.) 32 refs

Combination solar photovoltaic heat engine energy converter

Science.gov (United States)

Chubb, Donald L.

1987-01-01

A combination solar photovoltaic heat engine converter is proposed. Such a system is suitable for either terrestrial or space power applications. The combination system has a higher efficiency than either the photovoltaic array or the heat engine alone can attain. Advantages in concentrator and radiator area and receiver mass of the photovoltaic heat engine system over a heat-engine-only system are estimated. A mass and area comparison between the proposed space station organic Rankine power system and a combination PV-heat engine system is made. The critical problem for the proposed converter is the necessity for high temperature photovoltaic array operation. Estimates of the required photovoltaic temperature are presented.

Heat pumps in combined heat and power systems

DEFF Research Database (Denmark)

Ommen, Torben Schmidt; Markussen, Wiebke Brix; Elmegaard, Brian

2014-01-01

Heat pumps have previously been proposed as a way to integrate higher amounts of renewable energy in DH (district heating) networks by integrating, e.g., wind power. The paper identifies and compares five generic configurations of heat pumps in DH systems. The operational performance...... of the considered cases. When considering a case where the heat pump is located at a CHP (combined heat and power) plant, a configuration that increases the DH return temperature proposes the lowest operation cost, as low as 12 EUR MWh-1 for a 90 °C e 40 °C DH network. Considering the volumetric heating capacity......, a third configuration is superior in all cases. Finally, the three most promising heat pump configurations are integrated in a modified PQ-diagram of the CHP plant. Each show individual advantages, and for two, also disadvantages in order to achieve flexible operation....

A renewable energy scenario for Aalborg Municipality based on low-temperature geothermal heat, wind power and biomass

DEFF Research Database (Denmark)

Østergaard, Poul Alberg; Mathiesen, Brian Vad; Möller, Bernd

2010-01-01

Aalborg Municipality, Denmark, wishes to investigate the possibilities of becoming independent of fossil fuels. This article describes a scenario for supplying Aalborg Municipality’s energy needs through a combination of low-temperature geothermal heat, wind power and biomass. Of particular focus...... in the scenario is how low-temperature geothermal heat may be utilised in district heating (DH) systems. The analyses show that it is possible to cover Aalborg Municipality’s energy needs through the use of locally available sources in combination with significant electricity savings, heat savings, reductions...... in industrial fuel use and savings and fuel-substitutions in the transport sector. With biomass resources being finite, the two marginal energy resources in Aalborg are geothermal heat and wind power. If geothermal heat is utilised more, wind power may be limited and vice versa. The system still relies...

District heating in sequential energy supply

International Nuclear Information System (INIS)

Persson, Urban; Werner, Sven

2012-01-01

Highlights: ► European excess heat recovery and utilisation by district heat distribution. ► Heat recovery in district heating systems – a structural energy efficiency measure. ► Introduction of new theoretical concepts to express excess heat recovery. ► Fourfold potential for excess heat utilisation in EU27 compared to current levels. ► Large scale excess heat recovery – a collaborative challenge for future Europe. -- Abstract: Increased recovery of excess heat from thermal power generation and industrial processes has great potential to reduce primary energy demands in EU27. In this study, current excess heat utilisation levels by means of district heat distribution are assessed and expressed by concepts such as recovery efficiency, heat recovery rate, and heat utilisation rate. For two chosen excess heat activities, current average EU27 heat recovery levels are compared to currently best Member State practices, whereby future potentials of European excess heat recovery and utilisation are estimated. The principle of sequential energy supply is elaborated to capture the conceptual idea of excess heat recovery in district heating systems as a structural and organisational energy efficiency measure. The general conditions discussed concerning expansion of heat recovery into district heating systems include infrastructure investments in district heating networks, collaboration agreements, maintained value chains, policy support, world market energy prices, allocation of synergy benefits, and local initiatives. The main conclusion from this study is that a future fourfold increase of current EU27 excess heat utilisation by means of district heat distribution to residential and service sectors is conceived as plausible if applying best Member State practice. This estimation is higher than the threefold increase with respect to direct feasible distribution costs estimated by the same authors in a previous study. Hence, no direct barriers appear with

Heat losses and thermal performance of commercial combined solar and pellet heating systems

OpenAIRE

Fiedler, Frank; Persson, Tomas; Bales, Chris; Nordlander, Svante

2004-01-01

Various pellet heating systems are marketed in Sweden, some of them in combination with a solar heating system. Several types of pellet heating units are available and can be used for a combined system. This article compares four typical combined solar and pellet heating systems: System 1 and 2 two with a pellet stove, system 3 with a store integrated pellet burner and system 4 with a pellet boiler. The lower efficiency of pellet heaters compared to oil or gas heaters increases the primary en...

Combined heat and power considered as a virtual steam cycle heat pump

International Nuclear Information System (INIS)

Lowe, Robert

2011-01-01

The first aim of this paper is to shed light on the thermodynamic reasons for the practical pursuit of low temperature operation by engineers involved in the design and the operation of combined heat and power (CHP) and district heating (DH) systems. The paper shows that the steam cycle of a combined heat and power generator is thermodynamically equivalent to a conventional steam cycle generator plus an additional virtual steam cycle heat pump. This apparently novel conceptualisation leads directly to (i) the observed sensitivity of coefficient of performance of CHP to supply and return temperatures in associated DH systems, and (ii) the conclusion that the performance of CHP will tend to be significantly higher than real heat pumps operating at similar temperatures. The second aim, which is pursued more qualitatively, is to show that the thermodynamic performance advantages of CHP are consistent with the goal of deep, long-term decarbonisation of industrialised economies. As an example, estimates are presented, which suggest that CHP based on combined-cycle gas turbines with carbon capture and storage has the potential to reduce the carbon intensity of delivered heat by a factor of ∼30, compared with a base case of natural gas-fired condensing boilers. - Highlights: → Large-scale CHP systems are thermodynamically equivalent to virtual steam cycle heat pumps. → COPs of such virtual heat pumps are necessarily better than the Carnot limit for real heat pumps. → COPs can approach 9 for plant matched to district heating systems with flow temperatures of 90 deg. C. → CHP combined with CCGT and CCS can reduce the carbon intensity of delivered heat ∼30-fold.

Combined heat and power generation with exhaust-heated two-stage absorption refrigerator. Performance of a pilot installation with a refrigeration capacity of 350 kW; Kraft-Waerme-Kaelte-Kopplung mit Abgas-Beheizter zweistufiger Absorptionskaeltemaschine. Betriebserfahrungen einer Pilotinstallation mit 350 kW Kaelteleistung

Energy Technology Data Exchange (ETDEWEB)

Plura, S.; Baumeister, D.; Koeberle, T.; Radspieler, M.; Schweigler, C. [Bayerisches Zentrum fuer Angewandte Energieforschung e.V. (ZAE Bayern), Garching (Germany)

2007-07-01

A new system concept for higher efficiency of cogeneration systems is developed in which a cogeneration unit is combined with a two-stage absorption refrigerator, and the waste heat of the cogeneration unit is directly passed on into the regenerator of the absorption refrigerator. The higher temperature level of the waste heat makes it possible to use a two-stage absorption cycle for higher energy efficiency. For simultaneous utilisation of low-temperature heat, the two-stage cycle is combined with a one-stage cycle for additional heat supply at a lower temperature level so that the exhaust of a typical cogeneration unit will be cooled to about 120 degC. At the same time, further waste heat of the cogeneration unit will be transferred to the heat pump via a hot water circuit. This concept with a combined single-stage and two-stage absorption circuit is referred to as a double-effect/single-effect circuit. The new system is used for energy supply in a spa, where the two-stage absorption refrigerator cools the water used for swimming pool cleaning with a refrigerating capacity of 350 kW and provides low-temperature heat for swimming pool heating with a capacity of 700 kW. (orig.)

Analysis of the location for peak heating in CHP based combined district heating systems

International Nuclear Information System (INIS)

Wang, Haichao; Lahdelma, Risto; Wang, Xin; Jiao, Wenling; Zhu, Chuanzhi; Zou, Pinghua

2015-01-01

Combined heat and power (CHP) is the main technology for providing the base load of district heating in China. However, CHP is not efficient for providing the peak load; instead, a peak boiler with high efficiency could be used to compensate the peak load. This paper studies how the location of the peak boiler can affect the energy efficiency and economic performance of such CHP based combined district heating system. Firstly, the connection mode and the control strategy for different peak heating locations are analyzed. Then the effect of the peak boiler's location on the initial investment of the network and the cost for distributing heat is studied. The objective is to place the peak boiler in a location where the overall costs are the smallest. Following this rule, the results indicate that the peak boiler should be located at the CHP plant if that allows using cheaper ‘self-use electricity’ in CHP for distributing the heat. However, if the market electricity price is used everywhere, or if energy efficiency is more emphasized, the location of the peak boiler should be closer to the users with dense heat loads. - Highlights: • Location for peak heating in the CHP based combined DH system is studied. • Regulation or control strategies for combined DH are summarized. • The heat load duration curve for combined DH is demonstrated. • Network design for combined DH with peak boiler outside of the CHP is analyzed

Geothermal heating saves energy

International Nuclear Information System (INIS)

Romsaas, Tor

2003-01-01

The article reviews briefly a pioneer project for a construction area of 200000 m''2 with residences, business complexes, a hotel and conference centre and a commercial college in Oslo. The energy conservation potential is estimated to be about 60-70 % compared to direct heating with oil, gas or electricity as sources. There will also be substantial reduction in environmentally damaging emissions. The proposed energy central combines geothermal energy sources with heat pump technology, utilises water as energy carrier and uses terrestrial wells for energy storage. A cost approximation is presented

Residential CO{sub 2} heat pump system for combined space heating and hot water heating

Energy Technology Data Exchange (ETDEWEB)

Stene, Joern

2004-02-01

Carbon dioxide (CO{sub 2}, R-744) has been identified as a promising alternative to conventional working fluids in a number of applications due to its favourable environmental and thermophysical properties. Previous work on residential CO{sub 2} heat pumps has been dealing with systems for either space heating or hot water heating, and it was therefore considered interesting to carry out a theoretical and experimental study of residential CO{sub 2} heat pump systems for combined space heating and hot water heating - o-called integrated CO{sub 2} heat pump systems. The scope of this thesis is limited to brine-to-water and water-to-water heat pumps connected to low-temperature hydronic space heating systems. The main conclusions are: (1) Under certain conditions residential CO{sub 2} heat pump systems for combined space heating and hot water heating may achieve the same or higher seasonal performance factor (SPF) than the most energy efficient state-of-the-art brine-to-water heat pumps. (2) In contrary to conventional heat pump systems for combined space heating and DHW heating, the integrated CO{sub 2} heat pump system achieves the highest COP in the combined heating mode and the DHW heating mode, and the lowest COP in the space heating mode. Hence, the larger the annual DHW heating demand, the higher the SPF of the integrated CO{sub 2} heat pump system. (3) The lower the return temperature in the space heating system and the lower the DHW storage temperature, the higher the COP of the integrated CO{sub 2} heat pump. A low return temperature in the space heating system also results in a moderate DHW heating capacity ratio, which means that a relatively large part of the annual space heating demand can be covered by operation in the combined heating mode, where the COP is considerably higher than in the space heating mode. (4) During operation in the combined heating mode and the DHW heating mode, the COP of the integrated CO{sub 2} heat pump is heavily influenced by

Combined system of solar heating and cooling using heat pump

International Nuclear Information System (INIS)

Zakhidov, R.A.; Anarbaev, A.I.

2014-01-01

The heating and cooling systems of apartment buildings based on combined solar heat-pump equipment has been considered and the procedure of calculating its parameters has been worked out. A technical-economic analysis has been performed and compared with the boiler-setting version. (author)

New waste heat district heating system with combined heat and power based on absorption heat exchange cycle in China

International Nuclear Information System (INIS)

Sun Fangtian; Fu Lin; Zhang Shigang; Sun Jian

2012-01-01

A new waste heat district heating system with combined heat and power based on absorption heat exchange cycle (DHAC) was developed to increase the heating capacity of combined heat and power (CHP) through waste heat recovery, and enhance heat transmission capacity of the existing primary side district heating network through decreasing return water temperature by new type absorption heat exchanger (AHE). The DHAC system and a conventional district heating system based on CHP (CDH) were analyzed in terms of both thermodynamics and economics. Compared to CDH, the DHAC increased heating capacity by 31% and increased heat transmission capacity of the existing primary side district heating network by 75%. The results showed that the exergetic efficiency of DHAC was 10.41% higher and the product exergy monetary cost was 36.6¥/GJ less than a CHD. DHAC is an effective way to increase thermal utilization factor of CHP, and to reduce district heating cost. - Highlights: ► Absorption heat pumps are used to recover waste heat in CHP. ► Absorption heat exchanger can reduce exergy loss in the heat transfer process. ► New waste heat heating system (DHAC) can increase heating capacity of CHP by 31%. ► DHAC can enhance heat transmission capacity of the primary pipe network by 75%. ► DHAC system has the higher exergetic efficiency and the better economic benefit.

Geothermal energy utilisation in Slowakia and its future development

OpenAIRE

Sidorová Marína; Pinka Ján; Wittenberger Gabriel

2004-01-01

Owing to favourable geological conditions Slovakia is a country abundant in occurrence of low-enthalpy sources. The government of the state sponsors new renewable ecological energy sources, among which belongs geothermal energy. Geothermal water is utilized for recreation (swimming pools, spas), agriculture (heating of greenhouses, fishing) and heating of houses. Effectivity of utilisation is about 30 % due to its seasonal use. That is why the annual house-heating and hot water supply from ge...

Electrical and engine driven heat pumps for effective utilisation of renewable energy resources

Energy Technology Data Exchange (ETDEWEB)

Aye, Lu; Charters, W.W.S

2003-07-01

Much of the energy used for domestic, commercial and industrial purposes is to provide efficient and effective heating of conditioned spaces and for specialist niche applications in process heat systems. Vapour compression heat pumps driven by electric motors or engines provide the real capability of upgrading low temperature sources of ambient and waste heat to match the desired load temperatures in such heating applications. Major source of ambient heat stem from the storage of solar energy in the ground, in lakes and rivers, and in atmospheric air. Heat pumps can therefore be used to effectively harness indirectly the daily solar radiation input. In addition many industries have major sources of waste low grade heat in the form of air or water discharged from the industrial process heat stream. Heat pumps are generally formally classified therefore as air source, ground source or water source units although there has also been considerable interest recently in hybrid units combining the attributes of two or more of these specific types mentioned above.

Electrical and engine driven heat pumps for effective utilisation of renewable energy resources

Energy Technology Data Exchange (ETDEWEB)

Lu Aye [Melbourne Univ., Dept. of Civil and Environmental Engineering, Parkville, VIC (Australia); Charters, W.W.S. [Melbourne Univ., Dept. of Mechanical and Manufacturing Engineering, Parkville, VIC (Australia)

2003-07-01

Much of the energy used for domestic, commercial and industrial purposes is to provide efficient and effective heating of conditioned spaces and for specialist niche applications in process heat systems. Vapour compression heat pumps driven by electric motors or engines provide the real capability of upgrading low temperature sources of ambient and waste heat to match the desired load temperatures in such heating applications. Major source of ambient heat stem from the storage of solar energy in the ground, in lakes and rivers, and in atmospheric air. Heat pumps can therefore be used to effectively harness indirectly the daily solar radiation input. In addition many industries have major sources of waste low grade heat in the form of air or water discharged from the industrial process heat stream. Heat pumps are generally formally classified therefore as air source, ground source or water source units although there has also been considerable interest recently in hybrid units combining the attributes of two or more of these specific types mentioned above. (Author)

Solid oxide fuel cell systems for residential micro-combined heat and power in the UK: Key economic drivers

Science.gov (United States)

Hawkes, Adam; Leach, Matthew

The ability of combined heat and power (CHP) to meet residential heat and power demands efficiently offers potentially significant financial and environmental advantages over centralised power generation and heat-provision through natural-gas fired boilers. A solid oxide fuel cell (SOFC) can operate at high overall efficiencies (heat and power) of 80-90%, offering an improvement over centralised generation, which is often unable to utilise waste heat. This paper applies an equivalent annual cost (EAC) minimisation model to a residential solid oxide fuel cell CHP system to determine what the driving factors are behind investment in this technology. We explore the performance of a hypothetical SOFC system—representing expectations of near to medium term technology development—under present UK market conditions. We find that households with small to average energy demands do not benefit from installation of a SOFC micro-CHP system, but larger energy demands do benefit under these conditions. However, this result is sensitive to a number of factors including stack capital cost, energy import and export prices, and plant lifetime. The results for small and average dwellings are shown to reverse under an observed change in energy import prices, an increase in electricity export price, a decrease in stack capital costs, or an improvement in stack lifetime.

Capacity Utilisation of Vehicles for Road Freight Transport

DEFF Research Database (Denmark)

Kveiborg, Ole; Abate, Megersa Abera

to their analytical approach and origin of research. Findings The first approach looks at utilisation based on economic theories such as the firms’ objective to maximise profitability and considers how various firm and haul (market) characteristics influence utilisation. The second approach stems from the transport...... modelling literature and its main aim is analysing vehicle movement and usage in transport demand modelling context. A strand of this second group of contributions is the modelling of trip-chain and its implication on the level of capacity utilisation. Research limitations The review is not a comprehensive...... by combining different strands of this literature....

Fundamental Study of a Combined Hyperthermia System with RF Capacitive Heating and Interstitial Heating

OpenAIRE

Saitoh, Yoshiaki; Hori, Junichi; 斉藤, 義明; 堀, 潤一

2001-01-01

Interstitial RF heating with an inserted electrode allows the heating position selection in a subject, but the narrow heating region is problematic. This study elucidates development of new interstitial RF heating methods, combining with external RF heating using paired electrodes, heating the subject broadly in advance in order to selectively extend the heating region. Two kinds of heating system were developed by controlling a differential mode and a common mode of RF currents. Heating expe...

Combined Steady-State and Dynamic Heat Exchanger Experiment

Science.gov (United States)

Luyben, William L.; Tuzla, Kemal; Bader, Paul N.

2009-01-01

This paper describes a heat-transfer experiment that combines steady-state analysis and dynamic control. A process-water stream is circulated through two tube-in-shell heat exchangers in series. In the first, the process water is heated by steam. In the second, it is cooled by cooling water. The equipment is pilot-plant size: heat-transfer areas…

Prototype solar heating and combined heating and cooling systems. Quarterly report No. 6

Energy Technology Data Exchange (ETDEWEB)

1978-01-06

The General Electric Company is developing eight prototype solar heating and combined heating and cooling systems. This effort includes development, manufacture, test, installation, maintenance, problem resolution, and performance evaluation.

Performance analysis of hybrid district heating system

DEFF Research Database (Denmark)

Mikulandric, Robert; Krajačić, Goran; Khavin, Gennadii

2013-01-01

District heating system could contribute to more efficient heat generation through cogeneration power plants or waste heat utilization facilities and to increase of renewable energy sources share in total energy consumption. In the most developed EU countries, renewable energy sources have been...... as problems related to transportation, storage and environmental impacts of biomass and waste utilisation. Implementation of heat storages in district heating systems could contribute to integration of intermittent energy sources. Hybridisation of heat production facility combines two or more different energy...... more extensively used in district heating systems either separately or as a supplement to traditional fossil fuels in order to achieve national energy policy objectives. However, they are still facing problems such as high intermittences, high energy production costs and low load factors as well...

Geothermal energy utilisation in Slowakia and its future development

Directory of Open Access Journals (Sweden)

Sidorová Marína

2004-09-01

Full Text Available Owing to favourable geological conditions Slovakia is a country abundant in occurrence of low-enthalpy sources. The government of the state sponsors new renewable ecological energy sources, among which belongs geothermal energy. Geothermal water is utilized for recreation (swimming pools, spas, agriculture (heating of greenhouses, fishing and heating of houses. Effectivity of utilisation is about 30 % due to its seasonal use. That is why the annual house-heating and hot water supply from geothermal sources are supported. Recently company Slovgeoterm has initiated heating of greenhouses in Podhajska and heating of hospital and 1231 flats in town Galanta. Nowadays, research for the biggest geothermal project in the Middle Europe – construction in Košice basin has started.

Biomass Supply Planning for Combined Heat and Power Plants using Stochastic Programming

DEFF Research Database (Denmark)

Guericke, Daniela; Blanco, Ignacio; Morales González, Juan Miguel

method using stochastic optimization to support the biomass supply planning for combined heat and power plants. Our two-phase approach combines mid-term decisions about biomass supply contracts with the short-term decisions regarding the optimal market participation of the producer to ensure......During the last years, the consumption of biomass to produce power and heat has increased due to the new carbon neutral policies. Nowadays, many district heating systems operate their combined heat and power (CHP) plants using different types of biomass instead of fossil fuel, especially to produce......, and heat demand and electricity prices vary drastically during the planning period. Furthermore, the optimal operation of combined heat and power plants has to consider the existing synergies between the power and heating systems while always fulfilling the heat demand of the system. We propose a solution...

Control of food-borne molds by combination of heat and radiation

International Nuclear Information System (INIS)

Padwal-Desai, S.R.; Bongirwar, D.R.

1979-01-01

After enumerating the fungi responsible for food spoilage, work done on the factors influencing growth of fungi in stored foods is reviewed and the methods using heat, radiation or chemicals for control of food-borne molds are briefly surveyed. Work on combination process employing heat treatment and radiation treatment is reviewed in detail. The review covers the following aspects: (1) theory and engineering aspects of combination process of heat and radiation including modes of heat transfer, radiation physics, radiation sources, heat radiation effect and calculation of energy balance of the process, (2) biological effects of heat, radiation and heat-radiation combination treatments on mold growth with special reference to DNA and (3) application of the process for mold control in cereal products, nuts and raisins and fruits. Heat treatment and radiation treatment have been found to complement each other and when given in proper sequence show synergism. Design requirements of radiation sources and heat transfer equipment are also surveyed. (M.G.B.)

Performance characteristics of a combination solar photovoltaic heat engine energy converter

Science.gov (United States)

Chubb, Donald L.

1987-01-01

A combination solar photovoltaic heat engine converter is proposed. Such a system is suitable for either terrestrial or space power applications. The combination system has a higher efficiency than either the photovoltaic array or the heat engine alone can attain. Advantages in concentrator and radiator area and receiver mass of the photovoltaic heat engine system over a heat-engine-only system are estimated. A mass and area comparison between the proposed space station organic Rankine power system and a combination PV-heat engine system is made. The critical problem for the proposed converter is the necessity for high temperature photovoltaic array operation. Estimates of the required photovoltaic temperature are presented.

Heat pump applications in utility centres for large industrial areas in the Netherlands

NARCIS (Netherlands)

Wit, J.B. de

1999-01-01

A grand design for industrial waste heat utilisation has been composed in Rijnmond Industrial Area, the largest (petrochemical) industrial area in The Netherlands. In combination with local CHP plants, an HP, MP and LP steam exchange system has been developed. The primary energy savings of this

Thermodynamic analysis of heat recovery steam generator in combined cycle power plant

Directory of Open Access Journals (Sweden)

Ravi Kumar Naradasu

2007-01-01

Full Text Available Combined cycle power plants play an important role in the present energy sector. The main challenge in designing a combined cycle power plant is proper utilization of gas turbine exhaust heat in the steam cycle in order to achieve optimum steam turbine output. Most of the combined cycle developers focused on the gas turbine output and neglected the role of the heat recovery steam generator which strongly affects the overall performance of the combined cycle power plant. The present paper is aimed at optimal utilization of the flue gas recovery heat with different heat recovery steam generator configurations of single pressure and dual pressure. The combined cycle efficiency with different heat recovery steam generator configurations have been analyzed parametrically by using first law and second law of thermodynamics. It is observed that in the dual cycle high pressure steam turbine pressure must be high and low pressure steam turbine pressure must be low for better heat recovery from heat recovery steam generator.

Base-Load and Peak Electricity from a Combined Nuclear Heat and Fossil Combined-Cycle Plant

International Nuclear Information System (INIS)

Conklin, Jim; Forsberg, Charles W.

2007-01-01

A combined-cycle power plant is proposed that uses heat from a high-temperature reactor and fossil fuel to meet base-load and peak electrical demands. The high-temperature gas turbine produces shaft power to turn an electric generator. The hot exhaust is then fed to a heat recovery steam generator (HRSG) that provides steam to a steam turbine for added electrical power production. A simplified computational model of the thermal power conversion system was developed in order to parametrically investigate two different steady-state operation conditions: base load nuclear heat only from an Advanced High Temperature Reactor (AHTR), and combined nuclear heat with fossil heat to increase the turbine inlet temperature. These two cases bracket the expected range of power levels, where any intermediate power level can result during electrical load following. The computed results indicate that combined nuclear-fossil systems have the potential to offer both low-cost base-load electricity and lower-cost peak power relative to the existing combination of base-load nuclear plants and separate fossil-fired peak-electricity production units. In addition, electric grid stability, reduced greenhouse gases, and operational flexibility can also result with using the conventional technology presented here for the thermal power conversion system coupled with the AHTR

District heating

International Nuclear Information System (INIS)

Hansen, L.

1993-01-01

The environmental risks and uncertainties of a high-energy future are disturbing and give rise to several reservations concerning the use of fossil fuels. A number of technologies will help to reduce atmospheric pollution. In Denmark special importance is attached to the following: Energy conservation. Efficient energy conversion. Renewable energy sources. District heating, combined production of heat and power. Many agree that district heating (DH), produced by the traditional heat-only plant, and combined heat and power (CHP) have enormous potential when considering thermal efficiency and lowered environmental impacts: The basic technology of each is proven, it would be relatively simple to satisfy a substantial part of the energy demand, and their high efficiencies mean reduced pollution including greenhouse gas emissions. This is especially important in high population density areas - the obviously preferred sites for such energy generation. Compared with individual heating DH can provide a community with an operationally efficient and most often also an economically competitive heat supply. This is particularly true under the circumstances where the DH system is supplied from CHP plants. Their use results in very substantial improvements in overall efficiency. Further environmental improvements arise from the reduced air pollution obtainable in reasonably large CHP plants equipped with flue gas cleaning to remove particles, sulphur dioxide, and nitrogen acids. As a consequence of these considerations, DH plays an important role in fulfilling the space and water heating demand in many countries. This is especially the case in Denmark where this technology is utilised to a very great extent. Indeed, DH is one of the reasons why Denmark has relatively good air quality in the cities. (au)

Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC

Science.gov (United States)

Mikielewicz, Dariusz; Mikielewicz, Jarosław

2011-12-01

In the paper presented is a novel concept to utilize the heat from the turbine bleed to improve the quality of working fluid vapour in the bottoming organic Rankine cycle (ORC). That is a completely novel solution in the literature, which contributes to the increase of ORC efficiency and the overall efficiency of the combined system of the power plant and ORC plant. Calculations have been accomplished for the case when available is a flow rate of low enthalpy hot water at a temperature of 90 °C, which is used for preliminary heating of the working fluid. That hot water is obtained as a result of conversion of exhaust gases in the power plant to the energy of hot water. Then the working fluid is further heated by the bleed steam to reach 120 °C. Such vapour is subsequently directed to the turbine. In the paper 5 possible working fluids were examined, namely R134a, MM, MDM, toluene and ethanol. Only under conditions of 120 °C/40 °C the silicone oil MM showed the best performance, in all other cases the ethanol proved to be best performing fluid of all. Results are compared with the "stand alone" ORC module showing its superiority.

Preservation of canned Vienna sausage by combination of heat and radiation

International Nuclear Information System (INIS)

Incze, K.; Farkas, J.; Zukal, E.

1973-01-01

Since no texture improver is permitted in Hungarian Vienna sausage, the heat treatment necessary for bacteriological safety causes texture and consistency problems with this type of product. The aim of the investigations was to lower the heat damage by using a combination of mild heat treatment and irradiation. During the experiments an irradiation dose of 0.45 Mrad was combined with heat treatments of various F 0 values (0.2-0.5). F 0 of the control was 1.9. Naturally contaminated samples were used. Storage temperature was 30 0 C, storage time up to 2 months. Combination of irradiation (0.45 Mrad) and heat treatment (F 0 =0.4) - regardless of the sequence - gave satisfactory results in shelf-life and excellent results in organoleptic properties as compared to traditionally heat treated samples. This statement is valid for uninoculated samples only. (F.J.)

Utilisation of geothermal energy by the municipal works in Neubrandenburg

International Nuclear Information System (INIS)

Jahnke, H.

1994-01-01

A long distance energy supply plant has been operated on the basis of geothermal energy in Neubrandenburg since September 1988. At present it is still the largest heat generation plant for the utilisation of low thermal pore storage in Germany. The setup and the function of the plant are explained. After the municipal works of Neubrandenburg took over the plant, it was redesigned in order to give a better guarantee for the supply, to improve the economic efficiency and to minimise the environmental impact. At present long distance energy can be provided at a price of 99,00 DM/Mwh for 2000 utilisation hours per year. (BWI) [de

Thermodynamic analysis on theoretical models of cycle combined heat exchange process: The reversible heat exchange process

International Nuclear Information System (INIS)

Zhang, Chenghu; Li, Yaping

2017-01-01

Concept of reversible heat exchange process as the theoretical model of the cycle combined heat exchanger could be useful to determine thermodynamics characteristics and the limitation values in the isolated heat exchange system. In this study, the classification of the reversible heat exchange processes is presented, and with the numerical method, medium temperature variation tendency and the useful work production and usage in the whole process are investigated by the construction and solution of the mathematical descriptions. Various values of medium inlet temperatures and heat capacity ratio are considered to analyze the effects of process parameters on the outlet temperature lift/drop. The maximum process work transferred from the Carnot cycle region to the reverse cycle region is also researched. Moreover, influence of the separating point between different sub-processes on temperature variation profile and the process work production are analyzed. In addition, the heat-exchange-enhancement-factor is defined to study the enhancement effect of the application of the idealized process in the isolated heat exchange system, and the variation degree of this factor with process parameters change is obtained. The research results of this paper can be a theoretical guidance to construct the cycle combined heat exchange process in the practical system. - Highlights: • A theoretical model of Cycle combined heat exchange process is proposed. • The classification of reversible heat exchange process are presented. • Effects of Inlet temperatures and heat capacity ratio on process are analyzed. • Process work transmission through the whole process is studied. • Heat-exchange-enhancement-factor can be a criteria to express the application effect of the idealized process.

Optimal environmental benefits of utilising alternative energy technologies in Jordan

International Nuclear Information System (INIS)

Mrayyan, B.

2004-01-01

With rapid population growth and increase in industrial activities, more energy is consumed, resulting in environmental pollution and economic difficulties. Therefore, the need for utilising renewable energy resources has emerged. Although Jordan does not have adequate fuel supplies (90% of its crude oil is imported), it is gifted with alternative resources. Because of the political and economical constraints that hinder the import of crude oil from neighbouring countries and of the fact that Jordan has limited fossil fuel resources, strategies to meet energy demand are being addressed and examined together with their consequences and the ways in which they could be utilised. This paper assesses for the first time, the potential of using alternative energy technologies in Jordan, including the utilisation of solar energy for water heating, for wind towers in rural areas and also for biogas production from waste. Approximately 2% of unconventional renewable energy resources are being utilised. The data and scenarios of this study were presented in a manner that would assist decision makers, funding agencies, researchers and other related parties to establish programmes that will be helpful in meeting the energy demand, while preserving the environment and maintaining sustainability. (author)

Heating technologies for limiting biomass consumption in 100% renewable energy systems

DEFF Research Database (Denmark)

Mathiesen, Brian Vad; Lund, Henrik; Connolly, David

2011-01-01

district heating enables the use of combined heat and power production (CPH) and other renewable resources than biomass such as large-scale solar thermal, large-heat pumps, geothermal heat, industrial surplus heat etc. which is important for reducing the biomass consumption. Where the energy density......The utilisation of biomass poses large challenges in renewable energy systems and buildings account for a substantial part of the energy supply also in 100% renewable energy systems. The analyses of heating technologies show that district heating systems are especially important in limiting...... the dependence on biomass resources and to create cost effective systems. District heating systems are especially important in renewable energy systems with large amounts of fluctuating renewable energy sources as it enables fuel efficient and lower cost energy systems with thermal heat storages. And also...

Combined Heat and Power Dispatch Considering Heat Storage of Both Buildings and Pipelines in District Heating System for Wind Power Integration

Directory of Open Access Journals (Sweden)

Ping Li

2017-06-01

Full Text Available The strong coupling between electric power and heat supply highly restricts the electric power generation range of combined heat and power (CHP units during heating seasons. This makes the system operational flexibility very low, which leads to heavy wind power curtailment, especially in the region with a high percentage of CHP units and abundant wind power energy such as northeastern China. The heat storage capacity of pipelines and buildings of the district heating system (DHS, which already exist in the urban infrastructures, can be exploited to realize the power and heat decoupling without any additional investment. We formulate a combined heat and power dispatch model considering both the pipelines’ dynamic thermal performance (PDTP and the buildings’ thermal inertia (BTI, abbreviated as the CPB-CHPD model, emphasizing the coordinating operation between the electric power and district heating systems to break the strong coupling without impacting end users’ heat supply quality. Simulation results demonstrate that the proposed CPB-CHPD model has much better synergic benefits than the model considering only PDTP or BTI on wind power integration and total operation cost savings.

Utilisation of biomass gasification by-products for onsite energy production.

Science.gov (United States)

Vakalis, S; Sotiropoulos, A; Moustakas, K; Malamis, D; Baratieri, M

2016-06-01

Small scale biomass gasification is a sector with growth and increasing applications owing to the environmental goals of the European Union and the incentivised policies of most European countries. This study addresses two aspects, which are at the centre of attention concerning the operation and development of small scale gasifiers; reuse of waste and increase of energy efficiency. Several authors have denoted that the low electrical efficiency of these systems is the main barrier for further commercial development. In addition, gasification has several by-products that have no further use and are discarded as waste. In the framework of this manuscript, a secondary reactor is introduced and modelled. The main operating principle is the utilisation of char and flue gases for further energy production. These by-products are reformed into secondary producer gas by means of a secondary reactor. In addition, a set of heat exchangers capture the waste heat and optimise the process. This case study is modelled in a MATLAB-Cantera environment. The model is non-stoichiometric and applies the Gibbs minimisation principle. The simulations show that some of the thermal energy is depleted during the process owing to the preheating of flue gases. Nonetheless, the addition of a secondary reactor results in an increase of the electrical power production efficiency and the combined heat and power (CHP) efficiency. © The Author(s) 2016.

Industrial excess heat for district heating in Denmark

International Nuclear Information System (INIS)

Bühler, Fabian; Petrović, Stefan; Karlsson, Kenneth; Elmegaard, Brian

2017-01-01

Highlights: •Method for utilisation potential of industrial excess heat for district heating. •Industrial excess heat from thermal processes is quantified at single production units. •Linking of industrial excess heat sources and district heating demands done in GIS. •Excess heat recovery using direct heat transfer and heat pumps. •5.1% of the Danish district heating demand could be supplied by industrial excess heat. -- Abstract: Excess heat is available from various sources and its utilisation could reduce the primary energy use. The accessibility of this heat is however dependent amongst others on the source and sink temperature, amount and potential users in its vicinity. In this work a new method is developed which analyses excess heat sources from the industrial sector and how they could be used for district heating. This method first allocates excess heat to single production units by introducing and validating a new approach. Spatial analysis of the heat sources and consumers are then performed to evaluate the potential for using them for district heating. In this way the theoretical potential of using the excess heat for covering the heating demand of buildings is determined. Through the use of industry specific temperature profiles the heat usable directly or via heat pumps is further found. A sensitivity analysis investigates the impact of future energy efficiency measures in the industry, buildings and the district heating grid on the national potential. The results show that for the case study of Denmark, 1.36 TWh of district heat could be provided annually with industrial excess heat from thermal processes which equals 5.1% of the current demand. More than half of this heat was found to be usable directly, without the need for a heat pump.

Combined convective heat transfer of liquid sodium flowing across tube banks

International Nuclear Information System (INIS)

Ma, Ying; Sugiyama, Ken-ichiro; Ishiguro, Ryoji

1989-01-01

In order to clarify the heat transfer characteristics of combined convection of liquid sodium, a numerical analysis is performed for liquid sodium which flows through a single horizontal row of tubes in the direction of gravity. The correlation of heat transfer characteristics between liquid sodium and ordinary fluids is also discussed. The heat transfer characteristics at large Reynolds numbers are improved when the Richardson number is increased, and the improvement rate is enlarged with increase in p/d value, since convection effect is relatively large. However heat transfer coefficients do not differ from those of forced convection at small Reynolds numbers even when the Richardson number reaches a high value because of conduction effect. A good consistence of heat transfer characteristics of combined convection between liquid sodium and air is obtained at the same Peclet number and Richardson number. This means that the fundamental heat transfer characteristics of combined convection of liquid sodium can be investigated with ordinary fluids. (author)

Utilisation of phosphate by jute from jute growing soils

International Nuclear Information System (INIS)

Ray, P.K.; Suiha, A.K.

1974-01-01

The uptake and utilisation of phosphate from different jute growing soils of West Bengal viz., Humaipur (24-Parganas), Haripal (Hooghly), Panagarh (Burdwan) and the Jute Agricultural Research Institute, Barrackpore (24-Parganas) were studied in pot under fertilizer combination of NP, PK and NPK. The soils from 24-Parganas district behaved in a similar manner with respect to dry matter yield, fertilizer P uptake and per cent utilisation of added P. The P deficient between the two, Humaipur soil, showed comparatively higher P utilisation. Other two soils, Haripal and Panagarh, though of different origin behaved similarly, highest soil P has been contributed by the P rich soil (J.A.R.I.) to the crop, though it showed minimum P fixation. (author)

The combined effects of wall longitudinal heat conduction and inlet fluid flow maldistribution in crossflow plate-fin heat exchangers

Energy Technology Data Exchange (ETDEWEB)

Ranganayakulu, C. [Aeronautical Development Agency, Bangalore (India); Seetharamu, K.N. [School of Mechanical Engineering, Univ. of Southern Malaysia (KCP), Tronoh (Malaysia)

2000-05-01

An analysis of a crossflow plate-fin compact heat exchanger, accounting for the combined effect of two-dimensional longitudinal heat conduction through the exchanger wall and nonuniform inlet fluid flow distribution on both hot and cold fluid sides is carried out using a finite element method. Using the fluid flow maldistribution models, the exchanger effectiveness and its deterioration due to the combined effects of longitudinal heat conduction and flow nonuniformity are calculated for various design and operating conditions of the exchanger. It was found that the performance deteriorations are quite significant in some typical applications due to the combined effects of wall longitudinal heat conduction and inlet fluid flow nonuniformity on crossflow plate-fin heat exchanger. (orig.)

Simulation of a combined heating, cooling and domestic hot water system based on ground source absorption heat pump

International Nuclear Information System (INIS)

Wu, Wei; You, Tian; Wang, Baolong; Shi, Wenxing; Li, Xianting

2014-01-01

Highlights: • A combined heating/cooling/DHW system based on GSAHP is proposed in cold regions. • The soil imbalance is effectively reduced and soil temperature can be kept stable. • 20% and 15% of condensation/absorption heat is recovered by GSAHP to produce DHW. • The combined system can improve the primary energy efficiency by 23.6% and 44.4%. - Abstract: The amount of energy used for heating and domestic hot water (DHW) is very high and will keep increasing. The conventional ground source electrical heat pump used in heating-dominated buildings has the problems of thermal imbalance, decrease of soil temperature, and deterioration of heating performance. Ground source absorption heat pump (GSAHP) is advantageous in both imbalance reduction and primary energy efficiency (PEE) improvement; however, the imbalance is still unacceptable in the warmer parts of cold regions. A combined heating/cooling/DHW (HCD) system based on GSAHP is proposed to overcome this problem. The GSAHPs using generator absorber heat exchange (GAX) and single-effect (SE) cycles are simulated to obtain the performance under various working conditions. Different HCD systems in Beijing and Shenyang are simulated comparatively in TRNSYS, based on which the thermal imbalance, soil temperature, heat recovery, and energy efficiency are analyzed. Results show that GSAHP–GAX–HCD is suitable for Beijing and GSAHP–SE–HCD is suitable for Shenyang. The imbalance ratio can be reduced to −14.8% in Beijing and to 6.0% in Shenyang with an annual soil temperature variation of only 0.5 °C and 0.1 °C. Furthermore, about 20% and 15% of the total condensation/absorption heat is recovered to produce DHW, and the PEE can reach 1.516 in Beijing and 1.163 in Shenyang. The combined HCD systems can achieve a PEE improvement of 23.6% and 44.4% compared with the normal heating/cooling systems

Combined heat and power in the City

Energy Technology Data Exchange (ETDEWEB)

Crafter, A. [Corporation of London (United Kingdom). Dept. of Technical Services

2002-03-01

This article reports on the development of a large-scale combined heat and power community energy scheme within the City of London. Supported by the Corporation of London and using its own buildings to provide the heating and cooling loads, the scheme has established a power plant close to Smithfield Meat Market and supplies district heating and chilled water for air conditioning to its own properties and some private customers in the nearby districts. Details are given of the power plant which is sited in a conservation area with limited access, the use of absorption chillers to produce the chilled water, the estimated amount of carbon dioxide emissions saved, and the financial benefits of the scheme.

Large heat storage tank for load management nd implementation of ambient heat. District heating networks based on combined heat and power; Grosswaermespeicher zum Lastmanagement und zur Einbindung von Umweltenergie. Auf KWK basierende Fernwaermenetze

Energy Technology Data Exchange (ETDEWEB)

Gross, Sebastian; Rhein, Martin; Ruehling, Karin [Technische Universitaet Dresden (Germany). Inst. fuer Energietechnik

2013-06-15

The district heating based on combined heat and power is a transitional technology on the way to the supply of Germany with renewable energy. In the next years, this transitional technology can only be maintained and expanded when marketability is given. Therefore an appropriate combination has to be found from investment measures. Together with new aspects in the management strategy, these investment measures should significantly improve the marketability. The investment measures also aims to enable a primary energetic, appropriate combination of natural gas-based combined heat and power, renewable energy sources (solar thermal energy, ambient heat) and heat pump technology.

Dry heat and radiation combination effects on Aspergillus flavus Link. infecting cocoa beans

International Nuclear Information System (INIS)

Amoako-Atta, B.; Meier, H.; Odamtten, G.T.

1981-01-01

The paper deals with the effect of heat and radiation combination treatments on the control of microbial spoilage of cocoa beans caused by toxigenic Aspergillus flavus Link. The heat and radiation sources were from dry air oven heat and 60 Co gammacell 220 irradiator, respectively. The radiation doses used were either 0, 50, 100, 150 or 200 krad, with combined heat temperatures of 30, 60 or 90 0 C. At each temperature level three different exposure time intervals of either 15 min, 30 min or 60 min respectively, were used. Two reversible sequential heat/radiation combination effects were evaluated. The first sequence involved cocoa beans inoculated with A. flavus spores exposed first to dry heat at pre-determined temperature heat exposure time, followed by radiation treatment, then retention of samples in a constant humidity environmental chamber set at 80% for daily observation up to forty days post-treatment. The second sequence involved exposure of the inoculated beans first to radiation, then to heat before retention under fixed RH for observation. From their results, the authors arrive at four conclusions: first, that there is a critical radiation/heat combination range (200, 150 and 100 krad/90 0 C for 15 min) that significantly decontaminates (less than 5% mouldiness) A. flavus infected cocoa beans even under high relative humidity (80% RH) environment; second, that a temperature level of 90 0 C combined with 200, 150 or 100 krad maximizes such effect but the heat exposure time is a major factor; third, that low heat temperature ranges of 30 or 60 0 C, combined with low radiation dosages of 150 krad or below, enhance the rate of A. flavus spoilage effects of cocoa beans; and, lastly, that the sequence of exposure of the inoculated cocoa beans to heat/radiation combination influenced the spore germination; exposure to heat before radiation would sensitize the spores (200 krad/90 0 C) but results in an increased radioresistance. (author)

Satellite combined heat and power plants and their legal autonomy

International Nuclear Information System (INIS)

Loibl, Helmut

2014-01-01

Since the landmark decision by the German Court of Justice concerning the term ''plant'' in the context of biogas plants it should be clear beyond doubt that satellite combined heat and power plants (CHPs) are legally autonomous plants pursuant to Para. 3 No. 1 of the Renewable Energy Law (EEG). What has yet to be finally resolved are the conditions under which satellite CHPs are to be regarded as autonomous. This will be a question of distance on the one hand and of operation autonomy on the other. In the individual case both these factors will have to be assessed from the perspective of an average objective, informed citizen. To the extent that its heat and electricity are being utilised in a meaningful manner, the plant's autonomy will be beyond doubt, at least in operational terms. Regarding the remuneration to be paid for satellite CHPs the only case requiring special consideration is when a CHP falls under the EEG of 2012. In this case Para. 1 Section 1 Sentence 2 EEG provides that the remuneration for the CHP in question is to be calculated as if there was a single overall plant. To the extent that none of the CHPs fall under the EEG of 2012, the ruling remains that there is a separate entitlement to remuneration for each satellite CHP. This also holds in cases where satellite CHPs that were commissioned after 1 January 2012 are relocated. When a satellite CHP is replaced by a new one, the rate and duration of remuneration remain unchanged. However, when a new satellite CHP is added to an existing satellite CHP via a gas collector line it is to be treated according to the decisions of the Federal Court of Justice concerning biogas plant extensions: It falls under the law that applies to the existing CHP and has an entitlement to a new minimum remuneration period, albeit subject to the degression rate provided by the EEG version in question.

Heat demand profiles of energy conservation measures in buildings and their impact on a district heating system

International Nuclear Information System (INIS)

Lundström, Lukas; Wallin, Fredrik

2016-01-01

Highlights: • Energy savings impact on an low CO 2 emitting district heating system. • Heat profiles of eight building energy conservation measures. • Exhaust air heat pump, heat recovery ventilation, electricity savings etc. • Heat load weather normalisation with segmented multivariable linear regression. - Abstract: This study highlights the forthcoming problem with diminishing environmental benefits from heat demand reducing energy conservation measures (ECM) of buildings within district heating systems (DHS), as the supply side is becoming “greener” and more primary energy efficient. In this study heat demand profiles and annual electricity-to-heat factors of ECMs in buildings are computed and their impact on system efficiency and greenhouse gas emissions of a Swedish biomass fuelled and combined heat and power utilising DHS are assessed. A weather normalising method for the DHS heat load is developed, combining segmented multivariable linear regressions with typical meteorological year weather data to enable the DHS model and the buildings model to work under the same weather conditions. Improving the buildings’ envelope insulation level and thereby levelling out the DHS heat load curve reduces greenhouse gas emissions and improves primary energy efficiency. Reducing household electricity use proves to be highly beneficial, partly because it increases heat demand, allowing for more cogeneration of electricity. However the other ECMs considered may cause increased greenhouse gas emissions, mainly because of their adverse impact on the cogeneration of electricity. If biomass fuels are considered as residuals, and thus assigned low primary energy factors, primary energy efficiency decreases when implementing ECMs that lower heat demand.

A combined thermodynamic cycle used for waste heat recovery of internal combustion engine

International Nuclear Information System (INIS)

He, Maogang; Zhang, Xinxin; Zeng, Ke; Gao, Ke

2011-01-01

In this paper, we present a steady-state experiment, energy balance and exergy analysis of exhaust gas in order to improve the recovery of the waste heat of an internal combustion engine (ICE). Considering the different characteristics of the waste heat of exhaust gas, cooling water, and lubricant, a combined thermodynamic cycle for waste heat recovery of ICE is proposed. This combined thermodynamic cycle consists of two cycles: the organic Rankine cycle (ORC), for recovering the waste heat of lubricant and high-temperature exhaust gas, and the Kalina cycle, for recovering the waste heat of low-temperature cooling water. Based on Peng–Robinson (PR) equation of state (EOS), the thermodynamic parameters in the high-temperature ORC were calculated and determined via an in-house computer program. Suitable working fluids used in high-temperature ORC are proposed and the performance of this combined thermodynamic cycle is analyzed. Compared with the traditional cycle configuration, more waste heat can be recovered by the combined cycle introduced in this paper. -- Highlights: ► We study the energy balance of fuel in internal combustion engine. ► Heat recovery effect of exhaust gas is good when ICE is at a high-load condition. ► We propose a new combined thermodynamic cycle for waste heat of ICE. ► The combined cycle has a higher recovery efficiency than previous configurations.

Flue gas recovery system for natural gas combined heat and power plant with distributed peak-shaving heat pumps

International Nuclear Information System (INIS)

Zhao, Xiling; Fu, Lin; Wang, Xiaoyin; Sun, Tao; Wang, Jingyi; Zhang, Shigang

2017-01-01

Highlights: • A flue gas recovery system with distributed peak-shaving heat pumps is proposed. • The system can improve network transmission and distribution capacity. • The system is advantageous in energy saving, emission reduction and economic benefits. - Abstract: District heating systems use distributed heat pump peak-shaving technology to adjust heat in secondary networks of substations. This technology simultaneously adjusts the heat of the secondary network and reduces the return-water temperature of the primary network by using the heat pump principle. When optimized, low temperature return-water is able to recycle more waste heat, thereby further improving the heating efficiency of the system. This paper introduces a flue gas recovery system for a natural gas combined heat and power plant with distributed peak-shaving heat pumps. A pilot system comprising a set of two 9F gas-steam combined cycle-back pressure heating units was used to analyse the system configuration and key parameters. The proposed system improved the network transmission and distribution capacity, increased heating capacity, and reduced heating energy consumption without compromising heating safety issues. As such, the proposed system is advantageous in terms of energy saving, emission reduction, and economic benefits.

A feasible system integrating combined heating and power system with ground-source heat pump

International Nuclear Information System (INIS)

Li, HongQiang; Kang, ShuShuo; Yu, Zhun; Cai, Bo; Zhang, GuoQiang

2014-01-01

A system integrating CHP (combined heating and power) subsystem based on natural gas and GSHP (ground-source heat pump subsystem) in series is proposed. By help of simulation software-Aspen Plus, the energy performance of a typical CHP and GSHP-S (S refers to ‘in series’) system was analyzed. The results show that the system can make a better use of waste heat in flue gas from CHP (combined heating and power subsystem). The total system energy efficiency is 123% and the COP (coefficient of performance) of GSHP (ground-source heat pump) subsystem is 5.3. A referenced CHP and GSHP-P (P refers to ‘in parallel’) system is used for comparison; its total system energy efficiency and COP of GSHP subsystem are 118.6% and 3.5 respectively. Compared with CHP and GSHP-P system with different operating parameters, the CHP and GSHP-S system can increase total system energy efficiency by 0.8–34.7%, with related output ratio of heat to power (R) from 1.9 to 18.3. Furthermore, the COP of GSHP subsystem can be increased between the range 3.6 and 6, which is much higher than that in conventional CHP and GSHP-P system. This study will be helpful for other efficient GSHP systems integrating if there is waste heat or other heat resources with low temperature. - Highlights: • CHP system based on natural gas and ground source heat pump. • The new system can make a better utilization of waste heat in flue gas by a special way. • The proposed system can realize energy saving potential from 0.8 to 34.7%. • The coefficient of performance of ground source heat pump subsystem is significantly improved from 3.5 to 3.6–6. • Warm water temperature and percentage of flue gas used to reheat are key parameters

Combined Influence of Strain and Heat Loss on Turbulent Premixed Flame Stabilization

KAUST Repository

Tay-Wo-Chong, Luis; Zellhuber, Mathieu; Komarek, Thomas; Im, Hong G.; Polifke, Wolfgang

2015-01-01

relation in terms of Markstein number, Karlovitz Number and a non-dimensional heat loss parameter was proposed for the combined influence of strain and heat losses on the consumption speed. Combining this empirical relation with a presumed probability

Subjective evaluation of different ventilation concepts combined with radiant heating and cooling

DEFF Research Database (Denmark)

Krajcik, Michal; Tomasi, Roberta; Simone, Angela

2012-01-01

Sixteen subjects evaluated the indoor environment in four experiments with different combinations of ventilation and radiant heating/cooling systems. Two test setups simulated a room in a low energy building with a single occupant during winter. The room was equipped either by a ventilation system...... supplying warm air space heating or by a combination of radiant floor heating and mixing ventilation system. Next two test setups simulated an office room with two occupants during summer, ventilated and cooled by a single displacement ventilation system or by a radiant floor cooling combined...

Combined Heat and Power and Emissions Trading

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-07-01

The aim of this IEA Information Paper is to help policy makers and other stakeholders understand the challenges facing the incorporation of high efficiency combined heat and power (CHP) into greenhouse gas (GHG) Emissions Trading Schemes (ETSs) -- and to propose options for overcoming them.

Micro-Combined Heat and Power Device Test Facility

Data.gov (United States)

Federal Laboratory Consortium — NIST has developed a test facility for micro-combined heat and power (micro-CHP) devices to measure their performance over a range of different operating strategies...

Irradiation in combination of heat treatment of mango puree

International Nuclear Information System (INIS)

Noomhorm, A.; Apintanapong, M.

1996-01-01

The effect of irradiation with heat combination treatment on the shelf life and quality of mango puree was studied. Thermal inactivation of polyphenol oxidase enzyme at 80 degree C and 15 min. was used as a measure of adequacy of pre-heat treatment. Irradiation of mango puree after heat treatment at dosage of 0, 2, 4, 6 and 8 kGy showed no change in mc, pH, acidity, and TSS but during storage, growth of microorganisms brought changes in these values. Irradiation in combination with low temperature (5 degree C) reduced discoloration and darkening rate during storage. Irradiation dose from 0 to 8 kGy resulted in log linear reductions in microorganism levels but at 6 and 8 kGy, there was no growth of microorganisms. Products irradiated at 8 kGy showed no microorganism growth at both temperatures

Combined centralised and distributed mechanism for utilisation of node association in broadband wireless network

Science.gov (United States)

Ulvan, A.; Ulvan, M.; Pranoto, H.

2018-02-01

Mobile broadband wireless access system has the stations that might be fixed, nomadic or mobile. Regarding the mobility, the node association procedure is critical for network entry as well as network re-entry during handover. The flexibility and utilisation of MAC protocols scheduling have an important role. The standard provides the Partition Scheme as the scheduling mechanism which separates the allocation of minislots for scheduling. However, minislots cannot be flexibly reserved for centralised and distributed scheduling. In this paper we analysed the scheduling mechanism to improve the utilisation of minislots allocation during the exchange of MAC massages. The centralised and distributed scheduling is implemented in some topology scenarios. The result shows the proposed mechanism has better performance for node association than partition scheme.

A heating system for piglets in farrowing house using waste heat from biogas engine

Directory of Open Access Journals (Sweden)

Payungsak Junyusen

2008-12-01

Full Text Available The aim of this study is to design and test a heating system for piglets in farrowing house by utilising the waste heat from a biogas engine as a heat source. The study was separated into three parts: the study on the biogas combined heat and power plant, the investigation on the properties of the heat panel, and the installation and testing of the heating system. From the experiment, the condition producing 60 kW of electrical power was a proper one, in which electrical efficiency and specific fuel consumption were 14% and 1.22 m3/kWh respectively. Generating both electricity and heat increased the overall efficiency to 37.7% and decreased the specific fuel consumption to 0.45 m3/kWh. The heat panel, which was made of a plastic material, had a thermal conductivity of 0.58 W/mC and the maximum compressive force and operating pressure of 8.1 kN and 0.35 bar respectively. The surface temperature of the panel was dependent on the inlet water temperature. When hot water of 44C was supplied into the farrowing house with room temperature of 26C, the average surface temperature was 33C. The developed heating system could provide heat for 4.3 farrowing houses. The payback period of this project was 2.5 years.

Measure Guideline. Combination Forced-Air Space and Tankless Domestic Hot Water Heating Systems

Energy Technology Data Exchange (ETDEWEB)

Rudd, Armin [Building Science Corporation Industry Team (BSC), Somerville, MA (United States)

2012-08-01

This document describes design and application guidance for combination space and tankless domestic hot water heating systems (combination systems) used in residential buildings, based on field evaluation, testing, and industry meetings conducted by Building Science Corporation. As residential building enclosure improvements continue to drive heating loads down, using the same water heating equipment for both space heating and domestic water heating becomes attractive from an initial cost and space-saving perspective. This topic is applicable to single- and multi-family residential buildings, both new and retrofitted.

Thermal Efficiency of Power Module “Boiler with Solar Collectors as Additional Heat Source” For Combined Heat Supply System

Directory of Open Access Journals (Sweden)

Denysova A.E.

2015-04-01

Full Text Available The purpose of work is to increase the efficiency of the combined heat supply system with solar collectors as additional thermal generators. In order to optimize the parameters of combined heat supply system the mathematical modeling of thermal processes in multi module solar collectors as additional thermal generators for preheating of the water for boiler have been done. The method of calculation of multi-module solar collectors working with forced circulation for various configurations of hydraulic connection of solar collector modules as the new result of our work have been proposed. The results of numerical simulation of thermal efficiency of solar heat source for boiler of combined heat supply system with the account of design features of the circuit; regime parameters of thermal generators that allow establishing rational conditions of its functioning have been worked out. The conditions of functioning that provide required temperature of heat carrier incoming to boiler and value of flow rate at which the slippage of heat carrier is not possible for different hydraulic circuits of solar modules have been established.

Investigation of a heat storage for a solar heating system for combined space heating and domestic hot water supply for homeowner´s association "Bakken"

DEFF Research Database (Denmark)

Vejen, Niels Kristian

1998-01-01

A heat storage for a solar heating system for combined space heating and domestic hot water supply was tested in a laboratory test facility.The heat storage consist of a mantle tank with water for the heating system and of a hot water tank, which by means of thermosyphoning is heated by the water...

Retrofitting Combined Space and Water Heating Systems: Laboratory Tests

Energy Technology Data Exchange (ETDEWEB)

Schoenbauer, B.; Bohac, D.; Huelman, P.; Olson, R.; Hewitt, M.

2012-10-01

Better insulated and tighter homes can often use a single heating plant for both space and domestic water heating. These systems, called dual integrated appliances (DIA) or combination systems, can operate at high efficiency and eliminate combustion safety issues associated by using a condensing, sealed combustion heating plant. Funds were received to install 400 DIAs in Minnesota low-income homes. The NorthernSTAR DIA laboratory was created to identify proper system components, designs, operating parameters, and installation procedures to assure high efficiency of field installed systems. Tests verified that heating loads up to 57,000 Btu/hr can be achieved with acceptable return water temperatures and supply air temperatures.

Retrofitting Combined Space and Water Heating Systems. Laboratory Tests

Energy Technology Data Exchange (ETDEWEB)

Schoenbauer, B. [NorthernStar Building America Partnership, St. Paul, MN (United States); Bohac, D. [NorthernStar Building America Partnership, St. Paul, MN (United States); Huelman, P. [NorthernStar Building America Partnership, St. Paul, MN (United States); Olsen, R. [NorthernStar Building America Partnership, St. Paul, MN (United States); Hewett, M. [NorthernStar Building America Partnership, St. Paul, MN (United States)

2012-10-01

Better insulated and tighter homes can often use a single heating plant for both space and domestic water heating. These systems, called dual integrated appliances (DIA) or combination systems, can operate at high efficiency and eliminate combustion safety issues associated by using a condensing, sealed combustion heating plant. Funds were received to install 400 DIAs in Minnesota low-income homes. The NorthernSTAR DIA laboratory was created to identify proper system components, designs, operating parameters, and installation procedures to assure high efficiency of field installed systems. Tests verified that heating loads up to 57,000 Btu/hr can be achieved with acceptable return water temperatures and supply air temperatures.

Potential utilization of biomass in production of electricity, heat and transportation fuels including energy combines - Regional analyses and examples; Potentiell avsaettning av biomassa foer produktion av el, vaerme och drivmedel inklusive energikombinat - Regionala analyser och raekneexempel

Energy Technology Data Exchange (ETDEWEB)

Ericsson, Karin; Boerjesson, Paal

2008-01-15

describes future opportunities. The analysis of biofuels produced using second-generation technology focuses on the design of energy combines and the physical conditions for utilising the produced heat in the district heating systems. Since we consider the utilisation of district heating systems as heat sinks to be relatively limited, it is of great importance to design the energy combines so that the heat production is limited. This can be achieved through good heat integration and optimisation of the biofuel production. Taking the development over the past few years and current policy instruments into account, we find it realistic that the use of biomass in heat and electricity production will increase in line with our estimates, i.e. by 30-50% within the next 10 to 20 years. Future use of biomass in production of transportation fuels, on the other hand, is more difficult to assess

Combined heat and power production through biomass gasification with 'Heatpipe-Reformer'

International Nuclear Information System (INIS)

Iliev, I.; Kamburova, V.; Terziev, A.

2013-01-01

The current report aims is to analyze the system for combined heat and power production through biomass gasification with “heatpipe-reformer” system. Special attention is paid on the process of synthetic gas production in the Reformer, its cleaning and further burning in the co-generation unit. A financial analysis is made regarding the investments and profits generated by the combined heat and power production. (authors)

Heat transfer in a sodium-to-sodium heat exchanger under conditions of combined force and free convection

International Nuclear Information System (INIS)

Jackson, J.D.; Axcell, B.P.; Johnston, S.E.

1987-01-01

A combined experimental and theoretical investigation of heat transfer in a vertical tube and annulus, countercurrent flow heat exchanger is reported. The working fluid was liquid sodium. Included in the range of conditions covered were those which are of interest in connection with the low flow rate operation of fast reactor intermediate heat exchanger systems. The heat transfer process ranged from that of pure forced convection to combined forced and free convection. By changing the direction of fluid flow or the direction of heat flow four different configurations were studied. In two cases the convection process was buoyancy aided and in the other two it was buoyancy opposed. Results are presented showing the influence of flow rate and temperature difference on overall heat transfer coefficient for each case. A theoretical model of turbulent flow and heat transfer incorporating influences of buoyancy was used to produce results for the range of conditions covered in the experiments. The predictions of overall heat transfer coefficient were found to be in reasonable general agreement with the measurements. It was clear from these calculations that the influence of buoyancy on heat transfer stemmed largely, under the conditions of the present experiment, from the modification of the convection process due to the distortion of the velocity field. This led to an enhancement of the heat transfer for the buoyancy-aided process and an impairment for the buoyancy-opposed process. The contribution of the turbulent diffusion of heat was relatively small. (author)

Flexibility of a combined heat and power system with thermal energy storage for district heating

International Nuclear Information System (INIS)

Nuytten, Thomas; Claessens, Bert; Paredis, Kristof; Van Bael, Johan; Six, Daan

2013-01-01

Highlights: ► A generic model for flexibility assessment of thermal systems is proposed. ► The model is applied to a combined heat and power system with thermal energy storage. ► A centrally located storage offers more flexibility compared to individual units. ► Increasing the flexibility requires both a more powerful CHP and a larger buffer. - Abstract: The trend towards an increased importance of distributed (renewable) energy resources characterized by intermittent operation redefines the energy landscape. The stochastic nature of the energy systems on the supply side requires increased flexibility at the demand side. We present a model that determines the theoretical maximum of flexibility of a combined heat and power system coupled to a thermal energy storage solution that can be either centralized or decentralized. Conventional central heating, to meet the heat demand at peak moments, is also available. The implications of both storage concepts are evaluated in a reference district. The amount of flexibility created in the district heating system is determined by the approach of the system through delayed or forced operation mode. It is found that the distinction between the implementation of the thermal energy storage as a central unit or as a collection of local units, has a dramatic effect on the amount of available flexibility

Some Problems of the Integration of Heat Pump Technology into a System of Combined Heat and Electricity Production

Directory of Open Access Journals (Sweden)

G. Böszörményi

2001-01-01

Full Text Available The closure of a part of the municipal combined heat and power (CHP plant of Košice city would result in the loss of 200 MW thermal output within a realtively short period of time. The long term development plan for the Košice district heating system concentrates on solving this problem. Taking into account the extremely high (90 % dependence of Slovakia on imported energy sources and the desirability of reducing the emission of pollutantst the alternative of supplying of 100 MW thermal output from geothermal sources is attractive. However the indices of economic efficiency for this alternative are unsatisfactory. Cogeneration of electricity and heat in a CHP plant, the most efficient way of supplying heat to Košice at the present time. If as planned, geothermal heat is fed directly into the district heating network the efficiency would be greatly reduced. An excellent solution of this problem would be a new conception, preferring the utilization of geothermal heat in support of a combined electricity and heat production process. The efficiency of geothermal energy utilization could be increased through a special heat pump. This paper deals with several aspects of the design of a heat pump to be integrated into the system of the CHP plant.

Low Temperature District Heating for Future Energy Systems

DEFF Research Database (Denmark)

Schmidt, Dietrich; Kallert, Anna; Blesl, Markus

2017-01-01

of the building stock. Low temperature district heating (LTDH) can contribute significantly to a more efficient use of energy resources as well as better integration of renewable energy (e.g. geothermal or solar heat), and surplus heat (e.g. industrial waste heat) into the heating sector. LTDH offers prospects......The building sector is responsible for more than one third of the final energy consumption of societies and produces the largest amount of greenhouse gas emissions of all sectors. This is due to the utilisation of combustion processes of mainly fossil fuels to satisfy the heating demand...... for both the demand side (community building structure) and the supply side (network properties or energy sources). Especially in connection with buildings that demand only low temperatures for space heating. The utilisation of lower temperatures reduces losses in pipelines and can increase the overall...

Review of European regulatory and tariff experience with the sale of heat and electricity from combined heat and power plants

International Nuclear Information System (INIS)

Dyrelund, A.

1991-12-01

The Prince Edward Island Energy Corporation, Edmonton Power, Energy, Mines and Resources Canada and the Canadian Electrical Association commissioned a study to understand how electrical power and district heat from combined heat and power (CHP) plants is priced in Europe. Four northern European countries were investigated, Denmark, Germany, Sweden and Finland. These countries produce 45.8 TWh of power from combined heat and power plants, 7.1% of their annual consumption. In the case of Denmark, CHP accounts for 37.5% of its total power production. The energy situation in each country is reviewed using published statistics, and in particular the rapidly changing situation with regard to environmental and fuel taxes is examined. In order to obtain practical insights with regard to tariffs used by the various utilities, a series of generic examples were examined, supported by specific case studies. Technologies reviewed included: CHP from coal-fuelled extraction plant, CHP from coal-fuelled back pressure plant, waste heat from a municipal waste plant, and gas turbine with waste heat recovery. The benefits and risks associated with different tariff designs are discussed in detail including tariff formulae. This should enable interested parties to develop appropriate tariffs for combined heat and power plants in the context of current electrical utility policies. As a complement to the tariffs for combined heat and power plants, the design of district heating tariffs is also addressed. The typical concepts used in different countries are presented and discussed. 23 tabs

`Green heat` in a UK city

Energy Technology Data Exchange (ETDEWEB)

Anon.

1997-06-01

This brief article describes the Sheffield `green heat` scheme which utilises heat from a local waste incinerator to operate an independent district heating scheme within Sheffield city centre. Standby and peak overload heat generation capacity is provided by four boiler plants ensuring integrity of supply. The benefits of the scheme and future developments are outlined. (UK)

Evaluation of alternatives of exothermic methanization cycle for combined electricity and heat generation

International Nuclear Information System (INIS)

Balajka, J.; Princova, H.

1987-01-01

The possibilities are discussed of using the ADAM-EVA system for remote heat supply from nuclear heat sources to district heating systems. Attention is devoted to the use of the exothermal methanization process (ADAM station) for the combined power and heat production, this making use of the existing hot water power distribution network. The basic parameter for the evaluation of the over-all efficiency of the combined power and heat production is the maximum methanization cycle temperature which depends on the life of the methanization catalyst. Upon temperature drop below 550 degC, the conversion process can only be secured by means of two-stage methanization, which leads to a simplification of the cycle and a reduction in investment cost. At a temperature lower than 500 degC, combined power and heat production cannot be implemented. On the contrary, a considerable amount of electric power supplied from outside the system would be needed for compression work. (Z.M.)

Thermal Energy Corporation Combined Heat and Power Project

Energy Technology Data Exchange (ETDEWEB)

Turner, E. Bruce [Thermal Energy Corporation, Houston, TX (United States); Brown, Tim [Thermal Energy Corporation, Houston, TX (United States); Mardiat, Ed [Burns and McDonnell Engineering Company, Inc., Kansas City, MI (United States)

2011-12-31

To meet the planned heating and cooling load growth at the Texas Medical Center (TMC), Thermal Energy Corporation (TECO) implemented Phase 1 of a Master Plan to install an additional 32,000 tons of chilled water capacity, a 75,000 ton-hour (8.8 million gallon) Thermal Energy Storage (TES) tank, and a 48 MW Combined Heat and Power (CHP) system. The Department of Energy selected TMC for a $10 million grant award as part of the Financial Assistance Funding Opportunity Announcement, U.S. Department of Energy National Energy Technology, Recovery Act: Deployment of Combined Heat and Power (CHP) Systems, District Energy Systems, Waste Energy Recovery Systems, and Efficiency Industrial Equipment Funding Opportunity Number: DE-FOA-0000044 to support the installation of a new 48 MW CHP system at the TMC located just outside downtown Houston. As the largest medical center in the world, TMC is home to many of the nation's best hospitals, physicians, researchers, educational institutions, and health care providers. TMC provides care to approximately six million patients each year, and medical instruction to over 71,000 students. A medical center the size of TMC has enormous electricity and thermal energy demands to help it carry out its mission. Reliable, high-quality steam and chilled water are of utmost importance to the operations of its many facilities. For example, advanced medical equipment, laboratories, laundry facilities, space heating and cooling all rely on the generation of heat and power. As result of this project TECO provides this mission critical heating and cooling to TMC utilizing a system that is both energy-efficient and reliable since it provides the capability to run on power independent of the already strained regional electric grid. This allows the medical center to focus on its primary mission providing top quality medical care and instruction without worrying about excessive energy costs or the loss of heating and cooling due to the risk of power

Identification and Evaluation of Cases for Excess Heat Utilisation Using GIS

Directory of Open Access Journals (Sweden)

Fabian Bühler

2018-03-01

Full Text Available Excess heat is present in many sectors, and its utilization could reduce the primary energy use and emission of greenhouse gases. This work presents a geographical mapping of excess heat, in which excess heat from the industry and utility sector was distributed to specific geographical locations in Denmark. Based on this mapping, a systematic approach for identifying cases for the utilization of excess heat is proposed, considering the production of district heat and process heat, as well as power generation. The technical and economic feasibility of this approach was evaluated for six cases. Special focus was placed on the challenges for the connection of excess heat sources to heat users. To account for uncertainties in the model input, different methods were applied to determine the uncertainty of the results and the most important model parameters. The results show how the spatial mapping of excess heat sources can be used to identify their utilization potentials. The identified case studies show that it can be economically feasible to connect the heat sources to the public energy network or to use the heat to generate electricity. The uncertainty analysis suggests that the results are indicative and are particularly useful for a fast evaluation, comparison and prioritization of possible matches. The excess heat temperature and obtainable energy price were identified as the most important input parameters.

Combination study of operation characteristics and heat transfer mechanism for pulsating heat pipe

International Nuclear Information System (INIS)

Cui, Xiaoyu; Zhu, Yue; Li, Zhihua; Shun, Shende

2014-01-01

Pulsating heat pipe (PHP) is becoming a promising heat transfer device for the application like electronics cooling. However, due to its complicated operation mechanism, the heat transfer properties of the PHP still have not been fully understood. This study experimentally investigated on a closed-loop PHP charged with four types of working fluids, deionized water, methanol, ethanol and acetone. Combined with the visualization experimental results from the open literature, the operation characteristics and the corresponding heat transfer mechanisms for different heat inputs (5 W up to 100 W) and different filling ratios (20% up to 95%) have been presented and elaborated. The results show that heat-transfer mechanism changed with the transition of operation patterns; before valid oscillation started, the thermal resistance was not like that described in the open literature where it decreased almost linearly, but would rather slowdown descending or even change into rise first before further decreasing (i.e. an inflection point existed); when the heat input further increased to certain level, e.g. 65 W or above, there presented a limit of heat-transfer performance which was independent of the types of working fluids and the filling ratios, but may be related to the structure, the material, the size and the inclination of the PHP. - Highlights: •The thermal mechanisms altered accordingly with the operation features in the PHP. •Unlike conventional heat pipes, continuous temperature soaring would not happen in the PHP. •Before the oscillation start-up, there existed a heat-transfer limit for the relatively stagnated flow in the PHP. •A limit of thermal performance existed in the PHP at relatively high heat inputs

Comparing heat flow models for interpretation of precast quadratic pile heat exchanger thermal response tests

DEFF Research Database (Denmark)

Alberdi Pagola, Maria; Poulsen, Søren Erbs; Loveridge, Fleur

2018-01-01

This paper investigates the applicability of currently available analytical, empirical and numerical heat flow models for interpreting thermal response tests (TRT) of quadratic cross section precast pile heat exchangers. A 3D finite element model (FEM) is utilised for interpreting five TRTs by in...

Combined installation of electric and heat supply for climatic conditions of Iraq

Science.gov (United States)

Kaisi, Osama Al; Sidenkov, D. V.

2017-11-01

Electricity, heating and cooling are the three main components that make up the energy consumption base in residential, commercial and public buildings around the world. Demand for energy and fuel costs are constantly growing. Combined cooling, heating and power generation or trigeneration can be a promising solution to such a problem, providing an efficient, reliable, flexible, competitive and less harmful alternative to existing heat and cold supply systems. In this paper, scheme of the tri-generation plant on non-aqueous working substances is considered as an installation of a locally centralized electro-heat and cold supply of a typical residential house in a hot climate. The scheme of the combined installation of electro-heat (cold) supply consisted of the vapor power plant and heat pump system on low-boiling working substance for local consumers under the climatic conditions of Iraq is presented. The possibility of using different working substances in the thermodynamic cycles of these units, which will provide better efficiency of such tri-generation systems is shown. The calculations of steam turbine cycles and heat pump part on the selected working substances are conducted. It is proposed to use heat exchangers of plate type as the main exchangers in the combined processing. The developed method of thermal-hydraulic calculation of heat exchangers implemented in MathCad, which allows to evaluate the efficiency of plants of this type using the ε - NTU method. For the selected working substances of the steam part the optimal temperature of heat supply to the steam generator is determined. The results of thermodynamic and technical-economic analysis of the application of various working substances in the “organic” Rankine cycle of the steam turbine unit and the heat pump system of the heat and cold supply system are presented.

Combined Influence of Strain and Heat Loss on Turbulent Premixed Flame Stabilization

KAUST Repository

Tay-Wo-Chong, Luis

2015-11-16

The present paper argues that the prediction of turbulent premixed flames under non-adiabatic conditions can be improved by considering the combined effects of strain and heat loss on reaction rates. The effect of strain in the presence of heat loss on the consumption speed of laminar premixed flames was quantified by calculations of asymmetric counterflow configurations (“fresh-to-burnt”) with detailed chemistry. Heat losses were introduced by setting the temperature of the incoming stream of products on the “burnt” side to values below those corresponding to adiabatic conditions. The consumption speed decreased in a roughly exponential manner with increasing strain rate, and this tendency became more pronounced in the presence of heat losses. An empirical relation in terms of Markstein number, Karlovitz Number and a non-dimensional heat loss parameter was proposed for the combined influence of strain and heat losses on the consumption speed. Combining this empirical relation with a presumed probability density function for strain in turbulent flows, an attenuation factor that accounts for the effect of strain and heat loss on the reaction rate in turbulent flows was deduced and implemented into a turbulent combustion model. URANS simulations of a premixed swirl burner were carried out and validated against flow field and OH chemiluminescence measurements. Introducing the effects of strain and heat loss into the combustion model, the flame topology observed experimentally was correctly reproduced, with good agreement between experiment and simulation for flow field and flame length.

Stochastic Programming for Fuel Supply Planning of Combined Heat and Power Plants

DEFF Research Database (Denmark)

Guericke, Daniela; Blanco, Ignacio; Morales González, Juan Miguel

The consumption of biomass to produce power and heat has increased due to the carbon neutral policies. Combined heat and power (CHP) plants often combine biomass with other fuels, e.g., natural gas. The negotiation process for supply contracts involves many uncertainties due to the long planning...... horizon. The demand for biomass is uncertain, and heat demand and electricity prices vary during the planning period. We propose a method using stochastic optimization to support the biomass and natural gas supply planning for CHP plants including short-term decisions for optimal market participation....

Environmental assessment of incinerator residue utilisation

Energy Technology Data Exchange (ETDEWEB)

Toller, Susanna

2008-10-15

binding than previously understood. Differences were also observed between MSWI bottom ash DOM and the natural DOM for which the geochemical speciation models SHM and NICA-Donnan are calibrated. Revised parameter values for speciation modelling are therefore suggested. Additions of salt or natural DOM in the influent did not change the leachate concentration of Cu. Thus, although Cl and natural DOM might be present in the influent in the field due to road salting or infiltration of soil water, this is of minor importance for the potential environmental impact from MSWI bottom ash. This thesis allows estimates of long-term leaching and toxicity to be improved and demonstrates the need for broadening the system boundaries in order to highlight the tradeoffs between different types of impact. For decisions on whether incinerator residues should be utilised or landfilled, the use of a life cycle perspective in combination with more detailed assessments is recommended

ABA Is Required for Plant Acclimation to a Combination of Salt and Heat Stress.

Directory of Open Access Journals (Sweden)

Nobuhiro Suzuki

Full Text Available Abiotic stresses such as drought, heat or salinity are a major cause of yield loss worldwide. Recent studies revealed that the acclimation of plants to a combination of different environmental stresses is unique and cannot be directly deduced from studying the response of plants to each of the different stresses applied individually. Here we report on the response of Arabidopsis thaliana to a combination of salt and heat stress using transcriptome analysis, physiological measurements and mutants deficient in abscisic acid, salicylic acid, jasmonic acid or ethylene signaling. Arabidopsis plants were found to be more susceptible to a combination of salt and heat stress compared to each of the different stresses applied individually. The stress combination resulted in a higher ratio of Na+/K+ in leaves and caused the enhanced expression of 699 transcripts unique to the stress combination. Interestingly, many of the transcripts that specifically accumulated in plants in response to the salt and heat stress combination were associated with the plant hormone abscisic acid. In accordance with this finding, mutants deficient in abscisic acid metabolism and signaling were found to be more susceptible to a combination of salt and heat stress than wild type plants. Our study highlights the important role abscisic acid plays in the acclimation of plants to a combination of two different abiotic stresses.

Cost allocation. Combined heat and power production

International Nuclear Information System (INIS)

Sidzikauskas, V.

2002-01-01

The benefits of Combined Heat and Power (CHP) generation are discussed. The include improvement in energy intensity of 1% by 2010, 85-90% efficiency versus 40-50% of condensation power and others. Share of CHP electricity production in ERRA countries is presented.Solutions for a development CHP cost allocation are considered. Conclusion are presented for CHP production cost allocation. (R.P.)

Annual CO-emissions of combined pellet and solar heating systems

OpenAIRE

Fiedler, Frank; Persson, Tomas

2007-01-01

Emissions are an important aspect of a pellet heating system. High carbon monoxide emissions are often caused by unnecessary cycling of the burner when the burner is operated below the lowest combustion power. Combining pellet heating systems with a solar heating system can significantly reduce cycling of the pellet heater and avoid the inefficient summer operation of the pellet heater. The aim of this paper was to study CO-emissions of the different types of systems and to compare the yearly...

Modelling the viability of heat recovery from combined sewers.

Science.gov (United States)

Abdel-Aal, M; Smits, R; Mohamed, M; De Gussem, K; Schellart, A; Tait, S

2014-01-01

Modelling of wastewater temperatures along a sewer pipe using energy balance equations and assuming steady-state conditions was achieved. Modelling error was calculated, by comparing the predicted temperature drop to measured ones in three combined sewers, and was found to have an overall root mean squared error of 0.37 K. Downstream measured wastewater temperature was plotted against modelled values; their line gradients were found to be within the range of 0.9995-1.0012. The ultimate aim of the modelling is to assess the viability of recovering heat from sewer pipes. This is done by evaluating an appropriate location for a heat exchanger within a sewer network that can recover heat without impacting negatively on the downstream wastewater treatment plant (WWTP). Long sewers may prove to be more viable for heat recovery, as heat lost can be reclaimed before wastewater reaching the WWTP.

Effects of combined heat and x-rays on tumours in mice

International Nuclear Information System (INIS)

Hill, S.A.

1980-08-01

The therapeutic potential of combined hyperthermia and radiation was investigated in six different types of experimental mouse tumour. Their response to hyperthermia alone and combined heat and X-ray treatments was assessed by delay in tumour regrowth. Thermal sensitivity was found to vary from tumour to tumour. The importance of the order of application and the time interval between treatments was investigated, and the tumour response compared with that of mouse skin as an example of a normal tissue. A therapeutic gain was not seen for X-rays and heat in close sequence. It was however seen when heat was applied several hours after irradiation. Constriction of the tumour blood supply, either artificially, or naturally by implantation into a constricted site, was found to increase thermal sensitivity dramatically. Possible reasons for this are discussed. Heat applied immediately before irradiation may result in a small increase in metastatic spread. Heat applied at other times did not influence the metastatic incidence. Immersion in hot water was examined as a method of heating experimental mouse tumours, and was found to be inadequate in terms of the temperature uniformity achieved. The influence of this factor on results using water bath heating are discussed. (author)

Utilisation of diesel engine waste heat by Organic Rankine Cycle

International Nuclear Information System (INIS)

Kölsch, Benedikt; Radulovic, Jovana

2015-01-01

In this paper, three different organic liquids were investigated as potential working fluids in an Organic Rankine Cycle. Performance of Methanol, Toluene and Solkatherm SES36 was modelled in an ORC powered by a diesel engine waste heat. The ORC model consists of a preheater, evaporator, superheater, turbine, pump and two condensers. With variable maximum cycle temperatures and high cycle pressures, the thermal efficiency, net power output and overall heat transfer area have been evaluated. Methanol was found to have the best thermal performance, but also required the largest heat transfer area. While Toluene achieved lower thermal efficiency, it showed great work potential at high pressures and relatively low temperatures. Our model identified the risks associated with employing these fluids in an ORC: methanol condensing during the expansion and toluene not sufficiently superheated at the turbine inlet, which can compromise the cycle operation. The best compromise between the size of heat exchanger and thermodynamic performance was found for Methanol ORC at intermediate temperatures and high pressures. Flammability and toxicity, however, remain the obstacles for safe implementation of both fluids in ORC systems. - Highlights: • ORC powered by diesel-engine waste heat was developed. • Methanol, Toluene and Solkatherm were considered as working fluids. • Methanol was selected due to the best overall thermal performance. • Optimal cycle operating parameters and heat exchanger area were evaluated

Configuring a fuel cell based residential combined heat and power system

Science.gov (United States)

Ahmed, Shabbir; Papadias, Dionissios D.; Ahluwalia, Rajesh K.

2013-11-01

The design and performance of a fuel cell based residential combined heat and power (CHP) system operating on natural gas has been analyzed. The natural gas is first converted to a hydrogen-rich reformate in a steam reformer based fuel processor, and the hydrogen is then electrochemically oxidized in a low temperature polymer electrolyte fuel cell to generate electric power. The heat generated in the fuel cell and the available heat in the exhaust gas is recovered to meet residential needs for hot water and space heating. Two fuel processor configurations have been studied. One of the configurations was explored to quantify the effects of design and operating parameters, which include pressure, temperature, and steam-to-carbon ratio in the fuel processor, and fuel utilization in the fuel cell. The second configuration applied the lessons from the study of the first configuration to increase the CHP efficiency. Results from the two configurations allow a quantitative comparison of the design alternatives. The analyses showed that these systems can operate at electrical efficiencies of ∼46% and combined heat and power efficiencies of ∼90%.

Transformation of heat into mechanical energy by means of rotating systems

Directory of Open Access Journals (Sweden)

Mešina Marian

2018-01-01

Full Text Available All heat engines need two different temperatures for their work, T1heat engines. Unlike conventional heat engines, the working medium has an additional degree of freedom, the rotation around a given axis. The heat introduced and removed can not only lead to a change in the parameters of temperature, pressure, and volume, which are considered in conventional thermodynamics, but also to a change in the state of rotation. The rotational speed must also be taken into account in all phases of the cycle for all efficiency calculations. In many cases, this leads to a surprisingly different result from the results of conventional thermodynamics, that the efficiency of the cycle can exceed the Carnot limit. The efficiency values depend not only on temperatures and rotational speeds, but also on the material data. The proposed new type of heat engine makes it possible to better utilise very small temperature differences and under certain conditions, in combination with an ideal heat pump, to extract ambient heat and convert it into mechanical energy. The calculated results were presented for simple geometry and can easily be verified experimentally. In combination with an ideal heat pump, the proposed heat engine facilitates the surroundings to withdraw heat and convert it into mechanical work.

Combined heat and power economic dispatch by harmony search algorithm

Energy Technology Data Exchange (ETDEWEB)

Vasebi, A.; Bathaee, S.M.T. [Power System Research Laboratory, Department of Electrical and Electronic Engineering, K.N.Toosi University of Technology, 322-Mirdamad Avenue West, 19697 Tehran (Iran); Fesanghary, M. [Department of Mechanical Engineering, Amirkabir University of Technology, 424-Hafez Avenue, Tehran (Iran)

2007-12-15

The optimal utilization of multiple combined heat and power (CHP) systems is a complicated problem that needs powerful methods to solve. This paper presents a harmony search (HS) algorithm to solve the combined heat and power economic dispatch (CHPED) problem. The HS algorithm is a recently developed meta-heuristic algorithm, and has been very successful in a wide variety of optimization problems. The method is illustrated using a test case taken from the literature as well as a new one proposed by authors. Numerical results reveal that the proposed algorithm can find better solutions when compared to conventional methods and is an efficient search algorithm for CHPED problem. (author)

The capacity credit of micro-combined heat and power

International Nuclear Information System (INIS)

Hawkes, A.D.; Leach, M.A.

2008-01-01

This article is concerned with development of a methodology to determine the capacity credit of micro-combined heat and power (micro-CHP), and application of the method for the UK. Capacity credit is an important parameter in electricity system planning because it measures the amount of conventional generation that would be displaced by an alternative technology. Firstly, a mathematical formulation is presented. Capacity credit is then calculated for three types of micro-CHP units-Stirling engine, internal combustion engine, and fuel cell systems-operating under various control strategies. It is found that low heat-to-power ratio fuel cell technologies achieve the highest capacity credit of approximately 85% for a 1.1 GW penetration when a heat-led control strategy is applied. Higher heat-to-power ratio Stirling engine technology achieves approximately 33% capacity credit for heat-led operation. Low heat-to-power ratio technologies achieve higher capacity credit because they are able to continue operating even when heat demand is relatively low. Capacity credit diminishes as penetration of the technology increases. Overall, the high capacity credit of micro-CHP contributes to the viewpoint that the technology can help meet a number of economic and environmental energy policy aims

Economical Efficiency of Combined Cooling Heating and Power Systems Based on an Enthalpy Method

Directory of Open Access Journals (Sweden)

Yan Xu

2017-11-01

Full Text Available As the living standards of Chinese people have been improving, the energy demand for cooling and heating, mainly in the form of electricity, has also expanded. Since an integrated cooling, heating and power supply system (CCHP will serve this demand better, the government is now attaching more importance to the application of CCHP energy systems. Based on the characteristics of the combined cooling heating and power supply system, and the method of levelized cost of energy, two calculation methods for the evaluation of the economical efficiency of the system are employed when the energy production in the system is dealt with from the perspective of exergy. According to the first method, fuel costs account for about 75% of the total cost. In the second method, the profits from heating and cooling are converted to fuel costs, resulting in a significant reduction of fuel costs, accounting for 60% of the total cost. Then the heating and cooling parameters of gas turbine exhaust, heat recovery boiler, lithium-bromide heat-cooler and commercial tariff of provincial capitals were set as benchmark based on geographic differences among provinces, and the economical efficiency of combined cooling heating and power systems in each province were evaluated. The results shows that the combined cooling heating and power system is economical in the developed areas of central and eastern China, especially in Hubei and Zhejiang provinces, while in other regions it is not. The sensitivity analysis was also made on related influencing factors of fuel cost, demand intensity in heating and cooling energy, and bank loans ratio. The analysis shows that the levelized cost of energy of combined cooling heating and power systems is very sensitive to exergy consumption and fuel costs. When the consumption of heating and cooling energy increases, the unit cost decreases by 0.1 yuan/kWh, and when the on-grid power ratio decreases by 20%, the cost may increase by 0.1 yuan

Development of shelf stable, processed, low acid food products using heat-irradiation combination treatments

International Nuclear Information System (INIS)

Minnaar, A.

1998-01-01

The amount of ionizing irradiation needed to sterilize low acid vegetable and starch products (with and without sauces) commercially impairs their sensorial and nutritive qualities, and use of thermal processes for the same purpose may also have an adverse effect on the product quality. A systematic approach to the establishment of optimized combination parameters was developed for heat-irradiation processing to produce high quality, shelf stable, low acid food products. The effects of selected heat, heat-irradiation combination and irradiation treatments on the quality of shelf stable mushrooms in brine and rice, stored at ambient temperature, were studied. From a quality viewpoint, use of heat-irradiation combination treatments favouring low irradiation dose levels offered a feasible alternative to thermally processed or radappertized mushrooms in brine. However, shelf stable rice produced by heat-irradiation combination treatments offered a feasible alternative only to radappertized rice from the standpoint of quality. The technical requirements for the heat and irradiation processing of a long grain rice cultivar from the United States of America oppose each other directly, thereby reducing the feasibility of using heat-irradiation combination processing to produce shelf stable rice. The stability of starch thickened white sauces was found to be affected severely during high dose irradiation and subsequent storage at ambient temperature. However, use of pea protein isolate as a thickener in white sauces was found to have the potential to maintain the viscosity of sauces for irradiated meat and sauce products throughout processing and storage. (author)

Exergy, Economic and Environmental Analysis for Simple and Combined Heat and Power IC Engines

Directory of Open Access Journals (Sweden)

Mehdi Aliehyaei

2015-04-01

Full Text Available This study reports the results of exergy, economic and environmental analyses of simple and combined heat and power internal combustion engines. Values of entropy production, second law efficiency are calculated, and an objective function, including initial, operation, maintenance and fuel costs, as well as the external costs of environmental pollutants, such as CO2, CO and NOx, are presented for the flue gas of the internal combustion engine. The results show that entropy generation in the combined heat and power mode is 30% lower than that in the simple internal combustion engine. Also, by excessively increasing the air ratio, the system entropy generation decreases in both cases of simple and combined heat and power IC engines. The greatest portion of entropy generation is related to the combined heat and power internal combustion engine. The gas heat exchanger generates more entropy than the jacket heat exchanger. Lower values of electricity cost and external costs of air pollution are provided by higher values of molar air to fuel ratio. The environmental aspects depend on location of the system and time of engine operation.

A new methodology for greenhouse gas reduction in industry through improved heat exchanging and/or integration of combined heat and power

International Nuclear Information System (INIS)

Axelsson, H.; Asblad, A.; Berntsson, T.

1999-01-01

This paper presents a method that identifies economically optimal combinations of enhanced heat recovery, integration of combined heat and power (CHP), and fuel switching, in an existing industrial energy system at various emission levels. Novel types of composite curves based on pinch technology, representing the existing temperature levels for supplying heat and the possible ones that may be attained after retrofitting, are used as tools for estimating the opportunities for CHP and the trade-off between improved heat exchanging and CHP. The method is explained by an example. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Combined heat and power economic dispatch by a fish school search algorithm

Energy Technology Data Exchange (ETDEWEB)

Santos, Leonardo Trigueiro dos; Costa e Silva, Marsil de Athayde [Undergraduate in Mechatronics Engineering, Pontifical Catholic University of Parana, Curitiba, PR (Brazil); Coelho, Leandro dos Santos [Industrial and Systems Engineering Graduate Program, PPGEPS, Pontifical Catholic University of Parana, Curitiba, PR (Brazil)], e-mail: leandro.coelho@pucpr.br

2010-07-01

The conversion of primary fossil fuels, such as coal and gas, to electricity is a a relatively inefficient process. Even the most modern combined cycle plants can only achieve efficiencies of between 50-60%. A great portion of the energy wasted in this conversion process is released to the environment as waste heat. The principle of combined heat and power, also known as cogeneration, is to recover and make beneficial use of this heat, significantly raising the overall efficiency of the conversion process. However, the optimal utilization of multiple combined heat and power systems is a complicated problem which needs powerful methods to solve. This paper presents a fish school search (FSS) algorithm to solve the combined heat and power economic dispatch problem. FSS is a novel approach recently proposed to perform search in complex optimization problems. Some simulations presented in the literature indicated that FSS can outperform many bio-inspired algorithms, mainly in multimodal functions. The search process in FSS is carried out by a population of limited-memory individuals - the fishes. Each fish represents a possible solution to the problem. Similarly to particle swarm optimization or genetic algorithm, search guidance in FSS is driven by the success of some individual members of the population. A four-unit system proposed recently which is a benchmark case in the power systems field has been validated as a case study in this paper. (author)

The possibilities of heat pumps utilisation for family houses and flats fumigation

Directory of Open Access Journals (Sweden)

Ján Pinka

2006-10-01

Full Text Available Heat pumps (HPs with the help of electricity use a renewable energy source to supply heat for homes or industrial buildings and to heat tap water. HP is a heating unit that will provide us with heat for our home for some 20 to 30 years to come and has a potential to replace traditional heating systems powered by gas, oil or coal. At this time, there is no other heating system that supplies clean heat with the help of up to 80 per cent of the renewable solar energy during all year.

Determination of Heating Value of Estonian Oil Shale by Laser-Induced Breakdown Spectroscopy

Directory of Open Access Journals (Sweden)

M. Aints

2018-01-01

Full Text Available The laser-induced breakdown spectroscopy (LIBS combined with multivariate regression analysis of measured data were utilised for determination of the heating value and the chemical composition of pellets made from Estonian oil shale samples with different heating values. The study is the first where the oil shale heating value is determined on the basis of LIBS spectra. The method for selecting the optimal number of spectral lines for ordinary multivariate least squares regression model is presented. The correlation coefficient between the heating value predicted by the regression model, and that measured by calorimetric bomb, was R2=0.98. The standard deviation of prediction was 0.24 MJ/kg. Concentrations of oil shale components predicted by the regression model were compared with those measured by ordinary methods.

Calculation of Efficiencies of a Ship Power Plant Operating with Waste Heat Recovery through Combined Heat and Power Production

Directory of Open Access Journals (Sweden)

Mirko Grljušić

2015-05-01

Full Text Available The aim of this research was to investigate the possibility of a combined heat & power (CHP plant, using the waste heat from a Suezmax-size oil tanker’s main engine, to meet all heating and electricity requirements during navigation. After considering various configurations, a standard propulsion engine operating at maximum efficiency, combined with a supercritical Organic Rankine cycle (ORC system, was selected to supply the auxiliary power, using R245fa or R123 as the working fluid. The system analysis showed that such a plant can meet all heat and electrical power requirements at full load, with the need to burn only a small amount of supplementary fuel in a heat recovery steam generator (HRSG when the main engine operates at part load. Therefore, it is possible to increase the overall thermal efficiency of the ship’s power plant by more than 5% when the main engine operates at 65% or more of its specified maximum continuous rating (SMCR.

Identification and Evaluation of Cases for Excess Heat Utilisation Using GIS

DEFF Research Database (Denmark)

Bühler, Fabian; Petrovic, Stefan; Ommen, Torben Schmidt

2018-01-01

Excess heat is present in many sectors, and its utilization could reduce the primary energy use and emission of greenhouse gases. This work presents a geographical mapping of excess heat, in which excess heat from the industry and utility sector was distributed to specific geographical locations...

Biomass utilisation for combined heat and power generation: Status and perspectives for rural regions. Guelzow expert discussions; Energetische Nutzung von Biomasse mit Kraft-Waerme-Kopplung: Stand der Technik und Perspektiven fuer den laendlichen Raum. Guelzower Fachgespraeche

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-07-01

Biomass has a high potential but biomass utilisation technologies have not yet reached sufficient maturity for a general breakthrough on the market. Political boundary conditions alone are not sufficient if technical conversion processes are neglected. For the time being, the potential of biomass can not be utilised.

Performances of nuclear power plants for combined production of electricity and hot water for district heating

International Nuclear Information System (INIS)

Bronzen, S.

The possibilities for using nuclear power plants for combined production of heat and power seem to be very good in the future. With the chosen 600 MWsub (e) BWR plant a heat output up to 1200 MW can be arranged. An alternative, consisting of steam extractions from the low-pressure turbine, offers a flexible solution for heat and power generation. With this alternative the combined plant can use components from normal condensing nuclear power plants. The flexible extraction design also offers a real possibility for using the combined plant in electric peak generation. However, urban siting requires long distance heat transmission and the pipe design for this transmission is a major problem when planning and optimizing the whole nuclear combined heat and power plant. (author)

Aspects of biogas utilisation

International Nuclear Information System (INIS)

Luning, L.

1992-01-01

Utilisation of biogas has received considerable attention over the last decade, its full potential has not been reached however. The paper discusses various options for utilisation of biogas and the limitations that may occur as far as they are associated with the characteristics of biogas. As a result the prospects for the future are presented. (au)

Combined impact of transient heat loads and steady-state plasma exposure on tungsten

Energy Technology Data Exchange (ETDEWEB)

Huber, Alexander, E-mail: A.Huber@fz-juelich.de [Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung, 52425 Jülich (Germany); Wirtz, Marius; Sergienko, Gennady; Steudel, Isabel [Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung, 52425 Jülich (Germany); Arakcheev, Aleksey; Burdakov, Aleksander [Budker Institute of Nuclear Physics (BINP), Novosibirsk 630090 (Russian Federation); Esser, Hans Guenter; Freisinger, Michaele; Kreter, Arkadi; Linke, Jochen; Linsmeier, Christian; Mertens, Philippe; Möller, Sören; Philipps, Volker; Pintsuk, Gerald; Reinhart, Michael; Schweer, Bernd [Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung, 52425 Jülich (Germany); Shoshin, Andrey [Budker Institute of Nuclear Physics (BINP), Novosibirsk 630090 (Russian Federation); Terra, Alexis; Unterberg, Bernhard [Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung, 52425 Jülich (Germany)

2015-10-15

Highlights: • W-samples under combined loading conditions show a lower damage threshold. • The pre-loaded W-samples show a lower damage threshold due to the D- embrittlement. • Pronounced increase of the D retention has been observed during the combined loads. • Enhanced blister formation has been observed under combined loading conditions. - Abstract: Cracking thresholds and crack patterns in tungsten targets have been studied in recent experiments after repetitive ITER-like ELM heat pulses in combination with plasma exposure in PSI-2 (Γ{sub target} = 2.5–4.0 × 10{sup 21} m{sup −2} s{sup −1}, ion energy on surface E{sub ion} = 60 eV, T{sub e} ≈ 10 eV). The heat pulses were simulated by laser irradiation. A Nd:YAG laser with energy per pulse of up to 32 J and a duration of 1 ms at the fundamental wavelength (λ = 1064 nm, repetition rate 0.5 Hz) was used to irradiate ITER-grade W samples with repetitive heat loads. In contrast to pure thermal exposure with a laser beam where the damage threshold under pure heat loads for ITER-grade W lies between 0.38 and 0.76 GW/m{sup 2}, the experiments with pre-loaded W-samples as well as under combined loading conditions show a lower damage threshold of 0.3 GW/m{sup 2}. This is probably due to deuterium embrittlement and/or a higher defect concentration in a region close to the surface due to supersaturation with deuterium. A pronounced increase in the D retention (more than a factor of five) has been observed during the combined transient heat loads and plasma exposure. Enhanced blister formation has been observed under these combined loading conditions.

Combined impact of transient heat loads and steady-state plasma exposure on tungsten

International Nuclear Information System (INIS)

Huber, Alexander; Wirtz, Marius; Sergienko, Gennady; Steudel, Isabel; Arakcheev, Aleksey; Burdakov, Aleksander; Esser, Hans Guenter; Freisinger, Michaele; Kreter, Arkadi; Linke, Jochen; Linsmeier, Christian; Mertens, Philippe; Möller, Sören; Philipps, Volker; Pintsuk, Gerald; Reinhart, Michael; Schweer, Bernd; Shoshin, Andrey; Terra, Alexis; Unterberg, Bernhard

2015-01-01

Highlights: • W-samples under combined loading conditions show a lower damage threshold. • The pre-loaded W-samples show a lower damage threshold due to the D- embrittlement. • Pronounced increase of the D retention has been observed during the combined loads. • Enhanced blister formation has been observed under combined loading conditions. - Abstract: Cracking thresholds and crack patterns in tungsten targets have been studied in recent experiments after repetitive ITER-like ELM heat pulses in combination with plasma exposure in PSI-2 (Γ_t_a_r_g_e_t = 2.5–4.0 × 10"2"1 m"−"2 s"−"1, ion energy on surface E_i_o_n = 60 eV, T_e ≈ 10 eV). The heat pulses were simulated by laser irradiation. A Nd:YAG laser with energy per pulse of up to 32 J and a duration of 1 ms at the fundamental wavelength (λ = 1064 nm, repetition rate 0.5 Hz) was used to irradiate ITER-grade W samples with repetitive heat loads. In contrast to pure thermal exposure with a laser beam where the damage threshold under pure heat loads for ITER-grade W lies between 0.38 and 0.76 GW/m"2, the experiments with pre-loaded W-samples as well as under combined loading conditions show a lower damage threshold of 0.3 GW/m"2. This is probably due to deuterium embrittlement and/or a higher defect concentration in a region close to the surface due to supersaturation with deuterium. A pronounced increase in the D retention (more than a factor of five) has been observed during the combined transient heat loads and plasma exposure. Enhanced blister formation has been observed under these combined loading conditions.

The case for wood-fuelled heating

International Nuclear Information System (INIS)

Bent, Ewan

2001-01-01

This article looks at the wood heating industry in the UK and examines the heat market and the growth potential in the domestic, public, agricultural and commercial sectors. The current status of wood-fueled heating technology is considered, along with log and chip boilers, and the use of pellet fuel. The economics of wood-fuelled heating, the higher level of utilisation of wood-fuelled heating by utilities in northern European countries compared with the UK, and the barriers to the exploitation of wood fuelled heating are examined

A Benders decomposition approach for a combined heat and power economic dispatch

International Nuclear Information System (INIS)

Abdolmohammadi, Hamid Reza; Kazemi, Ahad

2013-01-01

Highlights: • Benders decomposition algorithm to solve combined heat and power economic dispatch. • Decomposing the CHPED problem into master problem and subproblem. • Considering non-convex heat-power feasible region efficiently. • Solving 4 units and 5 units system with 2 and 3 co-generation units, respectively. • Obtaining better or as well results in terms of objective values. - Abstract: Recently, cogeneration units have played an increasingly important role in the utility industry. Therefore the optimal utilization of multiple combined heat and power (CHP) systems is an important optimization task in power system operation. Unlike power economic dispatch, which has a single equality constraint, two equality constraints must be met in combined heat and power economic dispatch (CHPED) problem. Moreover, in the cogeneration units, the power capacity limits are functions of the unit heat productions and the heat capacity limits are functions of the unit power generations. Thus, CHPED is a complicated optimization problem. In this paper, an algorithm based on Benders decomposition (BD) is proposed to solve the economic dispatch (ED) problem for cogeneration systems. In the proposed method, combined heat and power economic dispatch problem is decomposed into a master problem and subproblem. The subproblem generates the Benders cuts and master problem uses them as a new inequality constraint which is added to the previous constraints. The iterative process will continue until upper and lower bounds of the objective function optimal values are close enough and a converged optimal solution is found. Benders decomposition based approach is able to provide a good framework to consider the non-convex feasible operation regions of cogeneration units efficiently. In this paper, a four-unit system with two cogeneration units and a five-unit system with three cogeneration units are analyzed to exhibit the effectiveness of the proposed approach. In all cases, the

Nuclear combined cycle gas turbines for variable electricity and heat using firebrick heat storage and low-carbon fuels

International Nuclear Information System (INIS)

Forsberg, Charles; Peterson, Per F.; McDaniel, Patrick; Bindra, Hitesh

2017-01-01

The world is transitioning to a low-carbon energy system. Variable electricity and industrial energy demands have been met with storable fossil fuels. The low-carbon energy sources (nuclear, wind and solar) are characterized by high-capital-costs and low-operating costs. High utilization is required to produce economic energy. Wind and solar are non-dispatchable; but, nuclear is the dispatchable energy source. Advanced combined cycle gas turbines with firebrick heat storage coupled to high-temperature reactors may enable economic variable electricity and heat production with constant full-power reactor output. Such systems efficiently couple to fluoride-salt-cooled high-temperature reactors (FHRs) with solid fuel and clean salt coolants, molten salt reactors (MSRs) with fuel dissolved in the salt coolant and salt-cooled fusion machines. Open Brayton combined cycles allow the use of natural gas, hydrogen, other fuels and firebrick heat storage for peak electricity production with incremental heat-to-electricity efficiencies from 66 to 70+% efficient. There are closed Brayton cycle options that use firebrick heat storage but these have not been investigated in any detail. Many of these cycles couple to high-temperature gas-cooled reactors (HTGRs). (author)

Energy and environmental evaluation of combined cooling heating and power system

Science.gov (United States)

Bugaj, Andrzej

2017-11-01

The paper addresses issues involving problems of implementing combined cooling, heating and power (CCHP) system to industrial facility with well-defined demand profiles of cooling, heating and electricity. The application of CCHP system in this particular industrial facility is being evaluated by comparison with the reference system that consists of three conventional methods of energy supply: (a) electricity from external grid, (b) heat from gas-fired boilers and (c) cooling from vapour compression chillers run by electricity from the grid. The CCHP system scenario is based on the combined heat and power (CHP) plant with gas turbine-compressor arrangement and water/lithium bromide absorption chiller of a single-effect type. Those two scenarios are analysed in terms of annual primary energy usage as well as emissions of CO2. The results of the analysis show an extent of primary energy savings of the CCHP system in comparison with the reference system. Furthermore, the environmental impact of the CCHP usage, in the form of greenhouse gases emission reductions, compares quite favourably with the reference conventional option.

Thermodynamic evaluation of CHP (combined heat and power) plants integrated with installations of coal gasification

International Nuclear Information System (INIS)

Ziębik, Andrzej; Malik, Tomasz; Liszka, Marcin

2015-01-01

Integration of a CHP steam plant with an installation of coal gasification and gas turbine leads to an IGCC-CHP (integrated gasification combined cycle-combined heat and power). Two installations of coal gasification have been analyzed, i.e. pressurized entrained flow gasifier – case 1 and pressurized fluidized bed gasifier with CO_2 recirculation – case 2. Basing on the results of mathematical modelling of an IGCC-CHP plant, the algorithms of calculating typical energy indices have been derived. The following energy indices are considered, i.e. coefficient of heat performance and relative savings of chemical energy of fuels. The results of coefficients of heat performance are contained between 1.87 and 2.37. Values exceeding 1 are thermodynamically justified because the idea of cogeneration of heat and electricity based on combining cycles of the heat engine and heat pump the efficiency of which exceeds 1. Higher values concerning waste heat replace more thermodynamically effective sources of heat in CHP plants. Relative savings of the chemical energy of fuels are similar in both cases of IGCC-CHP plants and are contained between the lower value of the CHP (combined heat and power) plants fuelled with coal and higher value of CHP plants fired with natural gas. - Highlights: • Energy savings of fuel is an adequate measure of cogeneration. • Relative energy savings of IGCC-CHP is near the result of a gas and steam CHP. • COHP (coefficient of heat performance) can help to divide fuel between heat fluxes. • Higher values of COHP in the case of waste heat recovery result from the lower thermal parameters.

Combined Heat and Power

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-07-01

At their 2007 Summit in Heiligendamm, G8 leaders called on countries to 'adopt instruments and measures to significantly increase the share of combined heat and power (CHP) in the generation of electricity.' As a result, energy, economic, environmental and utility regulators are looking for tools and information to understand the potential of CHP and to identify appropriate policies for their national circumstances. This report forms the first part of the response. It includes answers to policy makers' questions about the potential economic, energy and environmental benefits of an increased policy commitment to CHP. It also includes for the first time integrated IEA data on global CHP installations, and analyses the benefits of increased CHP investment in the G8+5 countries. A companion report will be produced later in 2008 to document best practice policy approaches that have been used to expand the use of CHP in a variety of countries.

Combined heat and power and solar energy; BHKW und solare Energie

Energy Technology Data Exchange (ETDEWEB)

Marchesi, M.; Schmidt, A.

2006-07-01

This illustrated article takes a look at a new apartment complex in Buelach, Switzerland, that meets the 'Minergie' low energy-consumption standard and also features solar-thermal heat generation. This solar installation provides heat for the provision of domestic hot water and, also, heat for the space-heating system of the building complex. The solar collectors cover an area of 153 m{sup 2}; their power is rated at 96 kW. Further elements of the building's technical services include a combined heat and power plant, a heat-pump and a gas-fired boiler. The article discusses ecological and social aspects of the design and construction of the building complex and briefly describes the installations, which also include a 'Minergie' fan-assisted balanced ventilation system.

Optimization of systems with the combination of ground-source heat pump and solar collectors in dwellings

DEFF Research Database (Denmark)

Kjellsson, Elisabeth; Hellström, Göran; Perers, Bengt

2010-01-01

The use of ground-source heat pumps for heating and domestic hot water in dwellings is common in Sweden. The combination with solar collectors has been introduced to reduce the electricity demand in the system. In order to analyze different systems with combinations of solar collectors and ground......-source heat pumps, computer simulations have been carried out with the simulation program TRNSYS. Large differences were found between the system alternatives. The optimal design is when solar heat produces domestic hot water during summertime and recharges the borehole during wintertime. The advantage...... is related to the rate of heat extraction from the borehole as well as the overall design of the system. The demand of electricity may increase with solar recharging, because of the increased operating time of the circulation pumps. Another advantage with solar heat in combination with heat pumps is when...

Design of serially connected ammonia-water hybrid absorption-compression heat pumps for district heating with the utilisation of a geothermal heat source

DEFF Research Database (Denmark)

Jensen, Jonas Kjær; Ommen, Torben Schmidt; Markussen, Wiebke Brix

2016-01-01

District heating (DH) can reduce the primary energy consumption in urban areas with significant heat demands. The design of a serially connected ammonia-water hybrid absorption-compression heat pump system was investigated for operation in the Greater Copenhagen DH network in Denmark, in order...... to supply 7.2 MW heat at 85 °C utilizing a geothermal heat source at 73 °C. Both the heat source and heat sink experience a large temperature change over the heat transfer process, of which a significant part may be achieved by direct heat exchange. First a generic study with a simple representation...

Preliminary Analysis on Heat Removal Capacity of Passive Air-Water Combined Cooling Heat Exchanger Using MARS

International Nuclear Information System (INIS)

Kim, Seung-Sin; Jeon, Seong-Su; Hong, Soon-Joon; Bae, Sung-Won; Kwon, Tae-Soon

2015-01-01

Current design requirement for working time of PAFS heat exchanger is about 8 hours. Thus, it is not satisfied with the required cooling capability for the long term SBO(Station Black-Out) situation that is required to over 72 hours cooling. Therefore PAFS is needed to change of design for 72 hours cooling. In order to acquirement of long terms cooling using PAFS, heat exchanger tube has to be submerged in water tank for long time. However, water in the tank is evaporated by transferred heat from heat exchanger tubes, so water level is gradually lowered as time goes on. The heat removal capacity of air cooling heat exchanger is core parameter that is used for decision of applicability on passive air-water combined cooling system using PAFS in long term cooling. In this study, the development of MARS input model and plant accident analysis are performed for the prediction of the heat removal capacity of air cooling heat exchanger. From analysis result, it is known that inflow air velocity is the decisive factor of the heat removal capacity and predicted air velocity is lower than required air velocity. But present heat transfer model and predicted air velocity have uncertainty. So, if changed design of PAFS that has over 4.6 kW heat removal capacity in each tube, this type heat exchanger can be applied to long term cooling of the nuclear power plant

Experimental Investigation of the Combined Effects of Heat Exchanger Geometries on Nucleate Pool Boiling Heat Transfer in a Scaled IRWST

International Nuclear Information System (INIS)

Kang, Myeong Gie; Chun, Moon Hyun

1996-01-01

In an effort to determine the combined effects of major parameters of heat exchanger tubes on the nucleate pool boiling heat transfer in the scaled in-containment refueling water storage tank (IRWST), a total of 1,966 data for q v ersus ΔT has been obtained using various combinations of tube diameters, surface roughness, and tube orientations. The experimental results show that (1) increased surface roughness enhances heat transfer for both horizontal and vertical tubes, (2) the two heat transfer mechanisms, i.e.,enhanced heat transfer for both horizontal and vertical tubes, (2) the two heat transfer mechanisms, i.e., enhanced heat transfer due to liquid agitation by bubbles generated and reduced heat transfer by the formation of large vapor slugs and bubble coalescence are different in two regions of low heat fluxes (q ≤ 50kW/m 2 ) and high heat fluxes (q > 50kW/m 2 ) depending on the orientation of tubes and the degree of surface roughness, and (3) the heat transfer rate decreases as the tube diameter is increased for both horizontal and vertical tubes, but the effect of tube diameter on the nucleate pool boiling heat transfer for vertical tubes is greater than that for horizontal tubes. Two empirical heat transfer correlations for q , one for horizontal tubes and the other for vertical tubes, are obtained in terms of surface roughness (ε) and tube diameter (D). In addition, a simple empirical correlation for nucleate pool boiling heat transfer coefficient (h b ) is obtained as a function of heat flux (q ) only. 9 figs., 4 tabs., 15 refs. (Author)

Analysis of Decay Heat Removal by Natural Convection in LMR with a Combined Steam Generator

International Nuclear Information System (INIS)

Kim, Eui Kwang; Eoh, Jae Hyuk; Han, Ji Woong; Lee, Tae Ho

2011-01-01

Liquid metal reactors (LMRs) conventionally employ an intermediate heat transport system (IHTS) to protect the nuclear core during a sodium-water reaction (SWR) event. However these SWR-related components increase plant construction costs. In order to eliminate the need for an IHTS, a combined steam generator, which is an integrated heat exchanger of a steam generator and intermediate heat exchanger (IHX), was proposed by the Korea Atomic Energy Research Institute (KAERI). The objective of this work is to analyze the natural circulation heat removal capability of the rector system using a combined steam generator. As a means of decay heat removal, a normal heat transport path is composed of a primary sodium system, intermediate lead-bismuth circuit combined with SG and steam/water system. This paper presents the results of the possible temperature and natural circulation flows in all circuits during a steady state for a given reactor power level varied as a function of time

Application of industrial wood residues for combined heat and power production

International Nuclear Information System (INIS)

Majchrzycka, A.

2015-01-01

The paper discusses combined production of heat and power (CHP) from industrial wood residues. The system will be powered by wood residues generated during manufacturing process of wooden floor panels. Based on power and heat demands of the plant and wood residues potential, the CHP system was selected. Preliminary analysis of biomass conversion in CHP system and environmental impact was performed.

High-temperature thermocline TES combining sensible and latent heat - CFD modeling and experimental validation

Science.gov (United States)

Zavattoni, Simone A.; Geissbühler, Lukas; Barbato, Maurizio C.; Zanganeh, Giw; Haselbacher, Andreas; Steinfeld, Aldo

2017-06-01

The concept of combined sensible/latent heat thermal energy storage (TES) has been exploited to mitigate an intrinsic thermocline TES systems drawback of heat transfer fluid outflow temperature reduction during discharging. In this study, the combined sensible/latent TES prototype under investigation is constituted by a packed bed of rocks and a small amount of encapsulated phase change material (AlSi12) as sensible heat and latent heat sections respectively. The thermo-fluid dynamics behavior of the combined TES prototype was analyzed by means of a computational fluid dynamics approach. Due to the small value of the characteristic vessel-to-particles diameter ratio, the effect of radial void-fraction variation, also known as channeling, was accounted for. Both the sensible and the latent heat sections of the storage were modeled as porous media under the assumption of local thermal non-equilibrium (LTNE). The commercial code ANSYS Fluent 15.0 was used to solve the model's constitutive conservation and transport equations obtaining a fairly good agreement with reference experimental measurements.

Sustainability assessment of renewable power and heat generation technologies

International Nuclear Information System (INIS)

Dombi, Mihály; Kuti, István; Balogh, Péter

2014-01-01

Rationalisation of consumption, more efficient energy usage and a new energy structure are needed to be achieved in order to shift the structure of energy system towards sustainability. The required energy system is among others characterised by intensive utilisation of renewable energy sources (RES). RES technologies have their own advantages and disadvantages. Nevertheless, for the strategic planning there is a great demand for the comparison of RES technologies. Furthermore, there are additional functions of RES utilisation expected beyond climate change mitigation, e.g. increment of employment, economic growth and rural development. The aim of the study was to reveal the most beneficial RES technologies with special respect to sustainability. Ten technologies of power generation and seven technologies of heat supply were examined in a multi-criteria sustainability assessment frame of seven attributes which were evaluated based on a choice experiment (CE) survey. According to experts the most important characteristics of RES utilisation technologies are land demand and social impacts i.e. increase in employment and local income generation. Concentrated solar power (CSP), hydropower and geothermal power plants are favourable technologies for power generation, while geothermal district heating, pellet-based non-grid heating and solar thermal heating can offer significant advantages in case of heat supply. - highlights: • We used choice experiment to estimate the weights of criteria for the sustainability assessment of RES technologies. • The most important attributes of RES technologies according to experts are land demand and social impacts. • Concentrated solar power (CSP), hydropower and geothermal power plants are advantageous technologies for power generation. • Geothermal district heating, pellet-based non-grid heating and solar thermal heating are favourable in case of heat supply

Analysis of combined heat and mass transfer of water- Vapor in a ...

African Journals Online (AJOL)

In this paper, the combined heat and mass transfer of water-vapor into a cylindrical zeolite adsorber has been numerically simulated The twodimensional heat and mass transfer equations are numerically solved using gPROMS program - a general Process Modeling System {lJ program, inserting the proper initial and ...

Analysis of combined heat and mass transfer of water-vapor in a ...

African Journals Online (AJOL)

Jn this paper, the combined heat and mass transfer of water-vapor into a cylindrical zeolite adsorber has been numerically simulated The twodimensional heat and mass transfer equations are numerically solved using gPROMS program - a general Process Modeling System [J] program, inserting the proper initial and ...

Current and potential utilisation of biomass energy in Fiji

International Nuclear Information System (INIS)

Prasad, S.

1990-01-01

Energy from biomass accounts for an average of 43% of the primary energy used in developing countries, with some countries totally dependent on biomass for all their energy needs. The most common use for biomass for energy is the provision of heat for cooking and heating; other uses include steam and electricity generation and crop and food drying. Fiji, a developing country, uses energy from wood and coconut wastes for cooking and copra drying. Bagasse from sugar mills is used to generate process steam as well as some 15 MW of electricity, for mill consumption and for sale to the national grid. Other, relatively small scale uses for biomass include the generation of steam and electricity for industry. This paper attempts to quantify the amount of biomass, in its various forms, available in Fiji and assesses the current potential utilisation of biomass for energy in Fiji. (author)

Combined heat transfer and kinetic models to predict cooking loss during heat treatment of beef meat.

Science.gov (United States)

Kondjoyan, Alain; Oillic, Samuel; Portanguen, Stéphane; Gros, Jean-Bernard

2013-10-01

A heat transfer model was used to simulate the temperature in 3 dimensions inside the meat. This model was combined with a first-order kinetic models to predict cooking losses. Identification of the parameters of the kinetic models and first validations were performed in a water bath. Afterwards, the performance of the combined model was determined in a fan-assisted oven under different air/steam conditions. Accurate knowledge of the heat transfer coefficient values and consideration of the retraction of the meat pieces are needed for the prediction of meat temperature. This is important since the temperature at the center of the product is often used to determine the cooking time. The combined model was also able to predict cooking losses from meat pieces of different sizes and subjected to different air/steam conditions. It was found that under the studied conditions, most of the water loss comes from the juice expelled by protein denaturation and contraction and not from evaporation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Waste-heat boiler application for the Vresova combined cycle plant

Energy Technology Data Exchange (ETDEWEB)

Vicek, Z. [Energoprojekt Praha, Prague (Czechoslovakia)

1995-12-01

This report describes a project proposal and implementation of two combined-cycle units of the Vresova Fuel Complex (PKV) with 2 x 200 MWe and heat supply. Participation of ENERGOPROJECT Praha a.s., in this project.

Technical Analysis of Combined Solar Water Heating Systems for Cold Climate Regions

OpenAIRE

Hossein Lotfizadeh; André McDonald; Amit Kumar

2016-01-01

Renewable energy resources, which can supplement space and water heating for residential buildings, can have a noticeable impact on natural gas consumption and air pollution. This study considers a technical analysis of a combined solar water heating system with evacuated tube solar collectors for different solar coverage, ranging from 20% to 100% of the total roof area of a typical residential building located in Edmonton, Alberta, Canada. The alternative heating systems were conventional (n...

Thermal utilisation and disposal of sewage sludge; Thermische Klaerschlammverwertung -beseitigung

Energy Technology Data Exchange (ETDEWEB)

Baumgart, H.C. [Emscher Genossenschaft/Lippeverband, Essen (Germany). Technischer Vorstand

2001-07-01

Sewage sludge combustion - either in an incinerator or for heat or power generation - has always been important and is getting ever more so. From the cost aspect, it makes quite a difference whether sewage sludge is just incinerated or utilised. The author makes it clear that this cost aspect - and what it means to communities and citizens - tends to be neglected by those who favour sewage sludge combustion and utilisation. [German] Die Verbrennung von Klaerschlamm - sei es als Schlammveraschung oder als thermische oder energetische Verwertung - hat schon immer fuer grosse Klaeranlagen einen bedeutenden Stellenwert gehabt. Die Bedeutung der Verbrennung scheint in letzter Zeit sogar zuzunehmen. Unter Kostengesichtspunkten ist es ein grosser Unterschied, ob ein Klaerschlamm nur verascht oder energetisch verwertet wird. Vor dem Hintergrund der allgemeinen Diskussion um die leeren Kassen der Kommunen, um die sogenannte dritte Miete fuer den Buerger und damit die Zumutbarkeit fuer weitere Steigerungen der Abwassergebuehren stoert mich die Bagatellisierung der Kostengesichtspunkte vor allem auf Seiten derer, die die Verbrennung der Klaerschlaemme fordern. (orig.)

Optimization of Serial Combined System of Ground-Coupled Heat Pump and Solar Collector

Institute of Scientific and Technical Information of China (English)

ZHAO Jun; CHEN Yan; LU Suzhen; CUI Junkui

2009-01-01

A mathematical optimization model was set up for a ground-solar combined system based on in-situ experimental results,in which the solar collector was combined serially with a ground-coupled heat pump(GCHP).The universal optimal equations were solved by the constrained variable metric method considering both the performance and economics.Then the model was applied to a specific case concerning an actual solar assisted GCHP system for space heating.The results indicated a system coefficient of performance(COP)of 3.9 for the optimal method under the seriaI heating mode,and 3.2 for the conventional one.In addition,the optimum solution also showed advantages in energy and cost saving.1eading to a 16.7%improvement in the heat pump performance at 17.2%less energy consumption and 11.8%lower annual cost,respectively.

Social anthropological and interdisciplinary research on the conversion of electrically heated single family houses to heating by combined pellet-solar systems

International Nuclear Information System (INIS)

Henning, Annette

2004-01-01

The social anthropological research presented here is part of the interdisciplinary research project PESTO, which focuses on the (partial or complete) conversion of single family houses from electric heating to heating by combined pellet-solar heating systems. Basic to this research is the assumption that it is more likely that energy conversions are carried through, and that they are successful on a long-term basis, if the new products are designed to fit as well as possible into the everyday lives of people. The anthropological interest in the project can be divided into two parts; motives for or against a conversion among men and women in Swedish households, and product design and placement in (previously) electrically heated single-family houses. Literature studies and semi-structured qualitative interviews are the main methods used in the anthropological part of the project. During the next 3-year project period, these investigations will be used to support information and marketing, and to formulate recommendations for conversion practice of electrically heated single-family houses to combined pellet-solar heating. (Author)

Robust Management of Combined Heat and Power Systems via Linear Decision Rules

DEFF Research Database (Denmark)

Zugno, Marco; Morales González, Juan Miguel; Madsen, Henrik

2014-01-01

The heat and power outputs of Combined Heat and Power (CHP) units are jointly constrained. Hence, the optimal management of systems including CHP units is a multicommodity optimization problem. Problems of this type are stochastic, owing to the uncertainty inherent both in the demand for heat and...... linear decision rules to guarantee both tractability and a correct representation of the dynamic aspects of the problem. Numerical results from an illustrative example confirm the value of the proposed approach....

Temporary heat storage by using combined heat and power in supplementary lighted greenhouses Proceedings of the Third International Symposium on Artificial Lighting in Horticulture

NARCIS (Netherlands)

Huijs, J.P.G.

1997-01-01

Because of better utilization possibilities of the produced heat, decentrally located combined heat and power installations achieve a higher energetic efficiency than producing heat and power separately. However, efficiency depends considerably on synchronism of heat and electricity demand. Using a

The Characteristic of Molten Heat Salt Storage System Utilizing Solar Energy Combined with Valley Electric

Directory of Open Access Journals (Sweden)

LI .Jiu-ru

2017-02-01

Full Text Available With the environmental pollution and energy consumption clue to the large difference between peak and valley of power grid，the molten salt heat storage system(MSHSS utilizing solar Energy combined with valley electric is presented for good energy saving and low emissions. The costs of MSHSS utilizing solar Energy combined with valley electric are greatly reduced. The law of heat transfer in molten salt heat storage technology is studied with the method of grey correlation analysis. The results show the effect of elbow sizes on surface convective heat transfer coefficient with different flow velocities.

Zinc uptake and utilisation in wetland rice as influenced by zinc sources

International Nuclear Information System (INIS)

Raja Rajan, A.

1994-01-01

Soil application of Zn is by far the most common and generally successful method of application to rice. Comparison of the effectiveness of soil applications of Zn necessarily involves simultaneous comparison of different sources. Applying Zn in combination with macronutrient fertilizers is convenient and allows more uniform distribution. Studies have indicated marked differences in Zn availability, uptake and utilisation resulting from the macronutrient fertilizer with which it is applied. This study was undertaken to evaluate the effect of a few sources of Zn on the yield, Zn uptake and utilisation in rice in two major rice grown soil series of Tamil Nadu. (author). 7 refs., 3 tabs

Modeling and optimization of a heat-pump-assisted high temperature proton exchange membrane fuel cell micro-combined-heat-and-power system for residential applications

DEFF Research Database (Denmark)

Arsalis, Alexandros; Kær, Søren Knudsen; Nielsen, Mads Pagh

2015-01-01

In this study a micro-combined-heat-and-power (micro-CHP) system is coupled to a vapor-compression heat pump to fulfill the residential needs for heating (space heating and water heating) and electricity in detached single-family households in Denmark. Such a combination is assumed to be attractive...... for application, since both fuel cell technology and electric heat pumps are found to be two of the most efficient technologies for generation/conversion of useful energy. The micro-CHP system is fueled with natural gas and includes a fuel cell stack, a fuel processor and other auxiliary components. The micro......-CHP system assumes heat-led operation, to avoid dumping of heat and the use of complicated thermal energy storage. The overall system is grid-interconnected to allow importing and exporting of electricity as necessary. In this study emphasis is given on the operational characterization of the system...

Accelerating the energy policy turnaround with combined heat and power units; Mit Blockheizkraftwerken die Energiewende rund machen

Energy Technology Data Exchange (ETDEWEB)

Lange, Joerg; Geiler, Nikolaus [Klimabuendnis Freiburg, Freiburg im Breisgau (Germany)

2013-03-15

No other type of decentralized power plants transforms natural gas to electric power so efficiently as a combined heat and power unit. In the long term, the climate-friendly effect using renewable hydrogen or renewably generated 'natural gas' even could be increased. Thus, combined heat and power units are ideal to achieve the national climate change objectives. Despite their advantages, the implementation of combined heat and power units advances only sluggishly.

Mitigation of Short-Lived Climate Pollutants from Residential Coal Heating and Combined Heating/Cooking Stoves: Impacts on the Cryosphere, Policy Options, and Co-benefits

Science.gov (United States)

Chafe, Z.; Anenberg, S.; Klimont, Z.; Kupiainen, K.; Lewis, J.; Metcalfe, J.; Pearson, P.

2017-12-01

Residential solid fuel combustion for cooking, heating, and other energy services contributes to indoor and outdoor air pollution, and creates impacts on the cryosphere. Solid fuel use often occurs in colder climates and at higher elevations, where a wide range of combustion emissions can reduce reflectivity of the snow- and ice-covered surfaces, causing climatic warming. Reducing short-lived climate pollutants (SLCPs), such as black carbon (BC), could have substantial climate and health co-benefits, especially in areas where emissions influence the cryosphere. A review of existing literature and emissions estimates, conducted as part of the Warsaw Summit on BC and Other Emissions from Residential Coal Heating Stoves and Combined Cooking/Heating Stoves, found little nationally-representative data on the fuels and technologies used for heating and combined cooking/heating. The GAINS model estimates that 24 million tonnes of coal equivalent were combusted by households for space heating globally in 2010, releasing 190 kilotons (kt) BC. Emissions from combined cooking/heating are virtually unknown. Policy instruments could mitigate cryosphere-relevant emissions of SLCPs from residential heating or cooking. These include indoor air quality guidelines, stove emission limits, bans on the use of specific fuels, regulatory codes that stipulate when burning can occur, stove changeout programs, and voluntary public education campaigns. These measures are being implemented in countries such as Chile (fuelwood moisture reduction campaign, energy efficiency, heating system improvements), Mongolia (stove renovation, fuel switching), Peru (improved stove programs), Poland (district heating, local fuel bans), United States (stove emission regulation) and throughout the European Community (Ecodesign Directive). Few, if any, of these regulations are likely to reduce emissions from combined cooking/heating. This research team found no global platform to create and share model

Application of biogas for combined heat and power production in the rural region

International Nuclear Information System (INIS)

Kozak, T.; Majchrzycka, A.

2009-01-01

The paper discusses combined production of heat and power (CHP) from biogas in a small-scale power plant placed in the rural region. Based on power and heat demands of the rural region and biomass supply, the CHP system was selected. Keywords: biogas, cogeneration

Analysis of Competitiveness and Support Instruments for Heat and Electricity Production from Wood Biomass in Latvia

Science.gov (United States)

Klavs, G.; Kudrenickis, I.; Kundzina, A.

2012-01-01

Utilisation of renewable energy sources is one of the key factors in a search for efficient ways of reducing the emissions of greenhouse gases and improving the energy supply security. So far, the district heating supply in Latvia has been based on natural gas, with the wood fuel playing a minor role; the same is true for decentralised combined heat-power (CHP) production. The paper describes a method for evaluation of the economic feasibility of heat and electricity production from wood biomass under the competition between different fuel types and taking into account the electricity market. For the simulation, a cost estimation model is applied. The results demonstrate that wood biomass can successfully be utilised for competitive heat production by boiler houses, while for electricity production by CHP utilities it cannot compete on the market (even despite the low prices on wood biomass fuel) unless particular financial support instruments are applied. The authors evaluate the necessary support level and the impact of two main support instruments - the investment subsidies and the feed-in tariff - on the economic viability of wood-fuelled CHP plants, and show that the feed-in tariff could be considered as an instrument strongly affecting the competitiveness of such type CHP. Regarding the feed-in tariff determination, a compromise should be found between the economy-dictated requirement to develop CHP projects concerning capacities above 5 MWel - on the one hand, and the relatively small heat loads in many Latvian towns - on the other.

Wind power integration using individual heat pumps – Analysis of different heat storage options

DEFF Research Database (Denmark)

Hedegaard, Karsten; Mathiesen, Brian Vad; Lund, Henrik

2012-01-01

Significant installations of individual heat pumps are expected in future energy systems due to their economic competitiveness. This case study of the Danish energy system in 2020 with 50% wind power shows that individual heat pumps and heat storages can contribute to the integration of wind power....... Heat accumulation tanks and passive heat storage in the construction are investigated as two alternative storage options in terms of their ability to increase wind power utilisation and to provide cost-effective fuel savings. Results show that passive heat storage can enable equivalent to larger...... reductions in excess electricity production and fuel consumption than heat accumulation tanks. Moreover, passive heat storage is found to be significantly more cost-effective than heat accumulation tanks. In terms of reducing fuel consumption of the energy system, the installation of heat pumps is the most...

A combined heating cooling stage for cluster thermalization in the gas phase

International Nuclear Information System (INIS)

Ievlev, D.N.; Kuester, A.; Enders, A.; Malinowski, N.; Schaber, H.; Kern, K.

2003-01-01

We report on the design and performance of a combined heating/cooling stage for the thermalization of clusters in a gas phase time-of-flight mass spectrometer. With this setup the cluster temperature can sensitively be adjusted within the range from 100 up to 800 K and higher. The unique combination of a heating stage with a subsequent cooling stage allows us to perform thermodynamic investigations on clusters at very high temperatures without quality losses in the spectra due to delayed fragmentation in the drift tube of the mass spectrometer. The performance of the setup is demonstrated by the example of (C 60 ) n clusters

Effect of nitrite on the microbiological stability of canned Vienna sausages preserved by mild heat treatment or combinations of heat and irradiation

International Nuclear Information System (INIS)

Farkas, J.; Zukal, E.; Incze, K.

1973-01-01

Keeping quality of Vienna sausages packed in No. 1/5 cans (ca 200 g) with salt brine and heat treated with F 0 values in the range of 0.25-0.55 was studied as a function of sodium nitrate addition. In uninoculated cans the heat requirement of preservation proved to be about 0.3 F 0 in the presence of 300 ppm NaNO 2 . A heat treatment of 0.55 F 0 and 200 ppm NaNO 2 resulted in higher microbiological stability of cans inoculated with 2x10 4 /tin Clostridium sporogenes spores than a heat treatment of 1.9 F 0 without nitrite addition. The effect of the combination of heat treatment of 0.35-0.55 F 0 and 0.45 Mrad of gamma irradiation was also studied with inoculated cans. The combination of irradiation plus heat resulted in a higher microbiological stability of the samples than the reversed order of the treatments, but this synergistic effect could not be proved in all experiments. The addition of 200 ppm NaNO 2 was not as effective in increasing the shelf-life of combination treated samples as with the solely heat treated ones. In a medium composed of a 50% extract of Vienna sausages (pH 6.4, asub(w) 0.96) and inoculated with 10 5 per ml Clostridium sporogenes spores 100 ppm or more NaNO 2 was required to ensure microbiological stability of samples heat treated with F 0 0.4. In the range of the permitted concentration level for canned meat products, sodium nitrite did not influence the heat resistance of Clostridium sporogenes, but inhibited the germination of the surviving spores. (F.J.)

Measure Guideline: Combined Space and Water Heating Installation and Optimization

Energy Technology Data Exchange (ETDEWEB)

Schoenbauer, B. [NorthernSTAR Building America Partnership, St. Paul, MN (United States); Bohac, D. [NorthernSTAR Building America Partnership, St. Paul, MN (United States); Huelman, P. [NorthernSTAR Building America Partnership, St. Paul, MN (United States)

2017-03-01

Combined space and water heater (combi or combo) systems are defined by their dual functionality. Combi systems provide both space heating and water heating capabilities with a single heat source. This guideline will focus on the installation and operation of residential systems with forced air heating and domestic hot water (DHW) functionality. Past NorthernSTAR research has used a combi system to replace a natural gas forced air distribution system furnace and tank type water heater (Schoenbauer et al. 2012; Schoenbauer, Bohac, and McAlpine 2014). The combi systems consisted of a water heater or boiler heating plant teamed with a hydronic air handler that included an air handler, water coil, and water pump to circulate water between the heating plant and coil. The combi water heater or boiler had a separate circuit for DHW. Past projects focused on laboratory testing, field characterization, and control optimization of combi systems. Laboratory testing was done to fully characterize and test combi system components; field testing was completed to characterize the installed performance of combi systems; and control methodologies were analyzed to understand the potential of controls to simplify installation and design and to improve system efficiency and occupant comfort. This past work was relied upon on to create this measure guideline.

Measure Guideline: Combined Space and Water Heating Installation and Optimization

Energy Technology Data Exchange (ETDEWEB)

Schoenbauer, B. [Univ. of Minnesota, St. Paul, MN (United States). NorthernSTAR Building America Partnership; Bohac, D. [Univ. of Minnesota, St. Paul, MN (United States). NorthernSTAR Building America Partnership; Huelman, P. [Univ. of Minnesota, St. Paul, MN (United States). NorthernSTAR Building America Partnership

2017-03-03

Combined space and water heater (combi or combo) systems are defined by their dual functionality. Combi systems provide both space heating and water heating capabilities with a single heat source. This guideline will focus on the installation and operation of residential systems with forced air heating and domestic hot water (DHW) functionality. Past NorthernSTAR research has used a combi system to replace a natural gas forced air distribution system furnace and tank type water heater (Schoenbauer et al. 2012; Schoenbauer, Bohac, and McAlpine 2014). The combi systems consisted of a water heater or boiler heating plant teamed with a hydronic air handler that included an air handler, water coil, and water pump to circulate water between the heating plant and coil. The combi water heater or boiler had a separate circuit for DHW. Past projects focused on laboratory testing, field characterization, and control optimization of combi systems. Laboratory testing was done to fully characterize and test combi system components; field testing was completed to characterize the installed performance of combi systems; and control methodologies were analyzed to understand the potential of controls to simplify installation and design and to improve system efficiency and occupant comfort. This past work was relied upon on to create this measure guideline.

Combined effect of heat sterilization and ionizing radiation on folacin in canned food

International Nuclear Information System (INIS)

Hozova, B.; Sorman, L.

1986-01-01

The results are reported of a study in folacin changes following heat sterilization at reduced intensity combined with irradiation of model food products, such as pickled cauliflower and beef in gravy. The folacin content in cauliflower was found to vary with the intensity of heat sterilization; no significant effect was observed of varying radiation doses. With respect to beef in gravy, the study confirmed the suitability of the combined preservation process in view of the higher folacin retention in the given food type. (author). 3 tabs., 14 refs

Spatiotemporal and economic analysis of industrial excess heat as a resource for district heating

DEFF Research Database (Denmark)

Bühler, Fabian; Petrović, Stefan; Holm, Fridolin Müller

2018-01-01

detailed analysis of the most suitable types of industries and the costs is required, allowing a targeted exploitation of this resource. This work extends the spatial and thermodynamic analysis, to account for the temporal match between industrial excess heat and district heating demands, as well...... as the costs for implementation and operation of the systems. This allows the determination of cost-effective district heating potentials, as well as the analysis of different industries and technological requirements. The results show that the temporal mismatch between excess heat and district heating demand...... and lack of demand, reduces the theoretical substitution potential by almost 30%. If heat storages are introduced, the total potential is reduced by only 10%. A majority of the excess heat can be utilised at socio-economic heating costs lower than the average Danish district heating price and the cost...

Minimum success criteria at SGTR combined with loss of secondary heat sink

International Nuclear Information System (INIS)

Parzer, I.; Petelin, S.

1993-01-01

A parametric analysis has been performed investigating minimum success criteria for the hypothetical Steam Generator Tube Rupture (SGTR) accident in a Pressurized Water Reactor (PWR) Nuclear Power Plant, combined with the total loss of secondary heat sink. The analyses have been performed by RELAP5/MOD2 and MOD3 computer codes using Krsko NPP input deck. The Krsko NPP is a 2-loop Westinghouse PWR, 640 MWe, located in Slovenia and operating from 1981. Two break sizes have been chosen for the SGTR event: 2 and 5 double-ended broken tubes have been assumed. Total loss of secondary heat sink has been assumed from the beginning of the calculation. The ways of cooling down the plant after the postulated accident have been investigated, including Bleed ampersand Feed through the primary system. The NPP Krsko Emergency Operating Procedures (EOP) have been verified for this case. Some suggestions have been made, how to improve FR-H.1 procedure (Loss of Secondary Heat Sink), to include some steps, which take into account also SGTR when it is combined with loss of secondary heat sink. Possible misinterpretations of E-0 procedure (Reactor Trip or Safety Injection) have been studied

Pattern of Smartphones Utilisation among Engineering Undergraduates

Directory of Open Access Journals (Sweden)

Muliati Sedek

2014-04-01

Full Text Available The smartphones ownership among the undergraduates in Malaysia was recorded as high. However, little was known about its utilization patterns, thus, the focus of this research was to determine the utilisation patterns of smartphones based on the National Education Technology Standard for Students (NETS.S among engineering undergraduates in Malaysia. This study was based on a quantitative research and the population comprised undergraduates from four Malaysian Technical Universities. A total of 400 questionnaires were analyzed. Based on the results, the undergraduates’ utilisation level of smartphones for communication and collaboration tool was at a high level. Meanwhile, utilisation for operations and concepts tool and research and information fluency tool were at moderate level. Finally, smartphones utilisation as digital citizenship tool and critical thinking, problem solving and creativity tool were both at a low level. Hence, more training and workshops should be given to the students in order to encourage them to fully utilise smartphones in enhancing the higher order thinking skills.

Power generation based on biomass by combined fermentation and gasification--a new concept derived from experiments and modelling.

Science.gov (United States)

Methling, Torsten; Armbrust, Nina; Haitz, Thilo; Speidel, Michael; Poboss, Norman; Braun-Unkhoff, Marina; Dieter, Heiko; Kempter-Regel, Brigitte; Kraaij, Gerard; Schliessmann, Ursula; Sterr, Yasemin; Wörner, Antje; Hirth, Thomas; Riedel, Uwe; Scheffknecht, Günter

2014-10-01

A new concept is proposed for combined fermentation (two-stage high-load fermenter) and gasification (two-stage fluidised bed gasifier with CO2 separation) of sewage sludge and wood, and the subsequent utilisation of the biogenic gases in a hybrid power plant, consisting of a solid oxide fuel cell and a gas turbine. The development and optimisation of the important processes of the new concept (fermentation, gasification, utilisation) are reported in detail. For the gas production, process parameters were experimentally and numerically investigated to achieve high conversion rates of biomass. For the product gas utilisation, important combustion properties (laminar flame speed, ignition delay time) were analysed numerically to evaluate machinery operation (reliability, emissions). Furthermore, the coupling of the processes was numerically analysed and optimised by means of integration of heat and mass flows. The high, simulated electrical efficiency of 42% including the conversion of raw biomass is promising for future power generation by biomass. Copyright © 2014 Elsevier Ltd. All rights reserved.

Landscape Utilisation, Animal Behaviour and Hendra Virus Risk.

Science.gov (United States)

Field, H E; Smith, C S; de Jong, C E; Melville, D; Broos, A; Kung, N; Thompson, J; Dechmann, D K N

2016-03-01

Hendra virus causes sporadic fatal disease in horses and humans in eastern Australia. Pteropid bats (flying-foxes) are the natural host of the virus. The mode of flying-fox to horse transmission remains unclear, but oro-nasal contact with flying-fox urine, faeces or saliva is the most plausible. We used GPS data logger technology to explore the landscape utilisation of black flying-foxes and horses to gain new insight into equine exposure risk. Flying-fox foraging was repetitious, with individuals returning night after night to the same location. There was a preference for fragmented arboreal landscape and non-native plant species, resulting in increased flying-fox activity around rural infrastructure. Our preliminary equine data logger study identified significant variation between diurnal and nocturnal grazing behaviour that, combined with the observed flying-fox foraging behaviour, could contribute to Hendra virus exposure risk. While we found no significant risk-exposing difference in individual horse movement behaviour in this study, the prospect warrants further investigation, as does the broader role of animal behaviour and landscape utilisation on the transmission dynamics of Hendra virus.

Modelling energy savings in the Danish building sector combined with internalisation of health related externalities in a heat and power system optimisation model

International Nuclear Information System (INIS)

Zvingilaite, Erika

2013-01-01

A substantial untapped energy saving potential rests in the building sector and is expected to play an important role in achieving reduction of environmental impacts of energy. In order to utilise this potential, effective policy measures need to be adopted to remove the existing barriers and create incentives. For that purpose, the cost effective energy saving options together with an optimal level of savings and expected environmental benefits have to be identified. The paper reports on a study that analyses these questions by including heat-saving measures in buildings into an energy system optimisation model of the Danish heat and power sector. The achieved optimal level of heat savings reaches 11% of projected heat demand in 2025 under the model assumptions. Moreover, the analysis reveals the importance of considering energy conservation options in a system wide perspective. Furthermore, the results suggest that changes in the energy generation sector are the prime driver behind the reduction of environmental externalities of energy. Heat savings in buildings play only a small role under model assumptions. - Highlights: ► Heat savings in buildings are analysed together with a heat and power system. ► Heat savings compete with electricity to heat technologies, mainly heat pumps. ► Cost effective heat-savings bring small decrease in health impacts and CO 2 emissions. ► Cost-effectiveness of heat savings depends on the marginal heat generation technology

Flue gas heat recovery operating below the dew point and its utilisation for low temperature heating installations

Energy Technology Data Exchange (ETDEWEB)

Wilsdorf, J.

1986-11-01

This paper deals at first with the characteristics of two principal systems for the flue gas heat recovery by reducing the temperature below the dew point. With test results on experimental plants are shown the typical differences between surface and direct contact heat exchange. A second part informs about experiences from the application for low temperature heating installations, especially about thermodynamics condensate quality and technical design. The possible increasing of the efficiency ranges between 10 to 20 per cent.

Thermal Heat and Power Production with Models for Local and Regional Energy Systems

Energy Technology Data Exchange (ETDEWEB)

Saether, Sturla

1999-07-01

The primary goal of this thesis is the description and modelling of combined heat and power systems as well as analyses of thermal dominated systems related to benefits of power exchange. Large power plants with high power efficiency (natural gas systems) and heat production in local heat pumps can be favourable in areas with low infrastructure of district heating systems. This system is comparable with typical combined heat and power (CHP) systems based on natural gas with respect to efficient use of fuel energy. The power efficiency obtainable from biomass and municipal waste is relatively low and the advantage of CHP for this system is high compared to pure power production with local heat pumps for heat generation. The advantage of converting pure power systems into CHP systems is best for power systems with low power efficiency and heat production at low temperature. CHP systems are divided into two main groups according to the coupling of heat and power production. Some CHP systems, especially those with strong coupling between heat and power production, may profit from having a thermal heat storage subsystem. District heating temperatures direct the heat to power ratio of the CHP units. The use of absorption chillers driven by district heating systems are also evaluated with respect to enhancing the utilisation of district heating in periods of low heat demand. Power exchange between a thermal dominated and hydropower system is found beneficial. Use of hydropower as a substitute for peak power production in thermal dominated systems is advantageous. Return of base load from the thermal dominated system to the hydropower system can balance in the net power exchange.

Techno-economic analysis of a coal-fired CHP based combined heating system with gas-fired boilers for peak load compensation

International Nuclear Information System (INIS)

Wang Haichao; Jiao Wenling; Lahdelma, Risto; Zou Pinghua

2011-01-01

Combined heat and power (CHP) plants dominate the heating market in China. With the ongoing energy structure reformation and increasing environmental concerns, we propose gas-fired boilers to be deployed in underperforming heating substations of heating networks for peak load compensation, in order to improve both energy efficiency and environmental sustainability. However, due to the relatively high price of gas, techno-economic analysis is required for evaluating different combined heating scenarios, characterized by basic heat load ratio (β). Therefore, we employ the dynamic economics and annual cost method to develop a techno-economic model for computing the net heating cost of the system, considering the current state of the art of cogeneration systems in China. The net heating cost is defined as the investment costs and operations costs of the system subtracted by revenues from power generation. We demonstrate the model in a real-life combined heating system of Daqing, China. The results show that the minimum net heating cost can be realized at β=0.75 with a cost reduction of 16.8% compared to coal heating alone. Since fuel cost is the dominating factor, sensitivity analyses on coal and gas prices are discussed subsequently. - Highlights: ► Combined heating systems comply with the energy structure reformation in China. ► We consider the current state of the art of cogeneration systems in China. ► Combined heating systems can be economically more feasible and sustainable. ► The net heating cost of a combined heating system is more sensitive to coal price. ► The optimal basic heat load ratio is more easily influenced by gas price.

Inflation and capacity utilisation in Nigeria's manufacturing sector ...

African Journals Online (AJOL)

This study analysed the relationship between inflation and capacity utilisation empirically leaning on the model employed by Baylor (2001). It utilised time series secondary data using least square multiple regression technique. The quarterly data utilised were tested for stationarity using ADF test. The multiple regression ...

Low grade heat utilisation for seawater desalination by the HTTF process

Energy Technology Data Exchange (ETDEWEB)

Chandrasekhar, M. [Desalination Division, Bhabha Atomic Research Centre (BARC), Trombay, Mumbai (India)]. E-mail: mchansh@magnum.barc.ernet.in; Majumdar, M.; Srivastava, V.K.; Tewari, P.K. [Desalination Division, Bhabha Atomic Research Centre (BARC), Trombay, Mumbai (India)

2006-07-01

To improve heat transfer efficiency, Horizontal Tube Thin Film (HTTF) evaporators are being used in multieffect desalination plants. These plants require less pumping energy than thermal-based desalination plants. To generate the design data, experimental studies were carried out in a single-tube HTTF experimental setup, and heat transfer correlations were developed at BARC. The experimental findings and results are presented and discussed in this paper. (author)

Cost efficient utilisation of biomass in the German energy system in the context of energy and environmental policies

International Nuclear Information System (INIS)

Koenig, Andreas

2011-01-01

The possible uses of biomass for energy provision are manifold. Gaseous, liquid and solid bioenergy carriers can be alternatively converted into heat, power or transport fuel. The contribution of the different utilisation pathways to environmental political targets for greenhouse gas (GHG) emission reduction and energy political targets for the future share of renewable energy vary accordingly to their techno-economic characteristics. The aim of the presented study is to assess the different biomass options against the background of energy and environmental political targets based on a system analytical approach for the future German energy sector. The results show that heat generation and to a lower extent combined heat and power (CHP) production from solid biomass like wood and straw are the most cost effective ways to contribute to the emission reduction targets. The use of energy crops in fermentation biogas plants (maize) and for production of 1st generation transportation fuels, like biodiesel from rapeseed and ethanol from grain or sugar beet, are less favourable. Optimisation potentials lie in a switch to the production of 2nd generation biofuels and the enhanced use of either biomass residues or low production intensive energy crops. - Research Highlights: → Heat generation and CHP generation from biomass can contribute cost efficiently to emission reduction targets. → Biofuel production represenst the least cost efficient option for emission reduction when using biomass energetically. → The energetical use of biomass shows a high potential to contribute to energy and envirnoment political targets.

Performance analysis on a new multi-effect distillation combined with an open absorption heat transformer driven by waste heat

International Nuclear Information System (INIS)

Zhang, Xiaodong; Hu, Dapeng; Li, Zhiyi

2014-01-01

In this paper, a new water distillation system, which consists of either a single- or multi-effect distiller combined with an open absorption heat transformer (OAHT), has been proposed. The new integrated system can be used for distilling waste water with high amounts of SiO 2 from heavy oil production, and the resultant distilled water can be supplied to steam boilers to produce high quality steam which in turn is injected into oil reservoirs to assist with heavy oil recovery. The thermodynamic cycle performances for these new integrated distillation systems were simulated based on the thermodynamic properties of the aqueous solution of LiBr as well as the mass and energy balance of the system. The results indicate that combined with OAHT, the waste heat at 70 °C can be elevated to 125 °C and thereby produce steam at 120 °C in the absorber, which is able to drive a four-effect distiller to produce distilled water. For a single-effect and four-effect distiller, the coefficients of performance (COP) are approximately 1.02 while the performance ratios are 2.19 and 5.72, respectively. Therefore, the four-effect distillation system combined with an OAHT is more thermally effective and is an ideal option to process the waste water in oilfields. -- Highlights: • A new absorption vapor compression distillation was proposed in present research. • An open absorption heat transformer has a coupled thermally evaporator and absorber. • Distillation of waste water with high content of SiO 2 from heavy oil production. • The waste heat of 70 °C can be elevated up to 125 °C and generate steam of 120 °C. • The waste heat is able to drive four-effect distillation to produce distilled water

Generating electricity and heat from lean gas. Dual fuel engine generates electricity and process heat from cupola furnace gas; Strom und Waerme aus Schwachgas gewinnen. Zuendstrahlmotor erzeugt Strom und Prozesswaerme aus Kupolofengas

Energy Technology Data Exchange (ETDEWEB)

Hirn, Gerhard

2012-07-01

White-hot molten iron flows into the launder. The blast of heat released provides visitors with an impressive demonstration of the amount of energy flowing in foundries. Large volumes of carbon (coke) are used for the melting process in the cupola furnace, whereby a combustible process gas is formed as a by-product. This so-called cupola furnace gas has a low heating value and has previously been completely combusted for generating the hot blast in the cupola furnace's recuperator. However, in this process only around 35 % of the contained energy is used thermally. Now it is possible to utilise the remaining 65 % of the chemically bound energy that was previously not used in most foundries: a modified biogas combined heat and power plant runs with cupola furnace gas (CFG) from the melting furnace. (orig.)

Combined Heat and Power in an open market

International Nuclear Information System (INIS)

Hawkins, A.

1999-01-01

The chances and risks for combined heat and power (CHP) installations presented by the future liberalisation of the electricity market in Switzerland are discussed. A summary of papers and speeches presented at a conference in Basle is presented. New developments in the electricity marketplace are looked at from the point of view of CHP unit manufacturers, the Federal Administration, energy policy makers and marketing experts. Examples are quoted concerning the situation in Germany and possible changes in power generation philosophy

Combined cycle power plant with integrated low temperature heat (LOTHECO)

International Nuclear Information System (INIS)

Kakaras, E.; Doukelis, A.; Leithner, R.; Aronis, N.

2004-01-01

The major driver to enhance the efficiency of the simple gas turbine cycle has been the increase in process conditions through advancements in materials and cooling methods. Thermodynamic cycle developments or cycle integration are among the possible ways to further enhance performance. The current paper presents the possibilities and advantages from the LOTHECO natural gas-fired combined cycle concept. In the LOTHECO cycle, low-temperature waste heat or solar heat is used for the evaporation of injected water droplets in the compressed air entering the gas turbine's combustion chamber. Following a description of this innovative cycle, its advantages are demonstrated by comparison between different gas turbine power generation systems for small and large-scale applications, including thermodynamic and economic analysis. A commercial gas turbine (ALSTOM GT10C) has been selected and computed with the heat mass balance program ENBIPRO. The results from the energy analysis are presented and the features of each concept are discussed. In addition, the exergy analysis provides information on the irreversibilities of each process and suggested improvements. Finally, the economic analysis reveals that the combined cycle plant with a heavy-duty gas turbine is the most efficient and economic way to produce electricity at base load. However, on a smaller scale, innovative designs, such as the LOTHECO concept, are required to reach the same level of performance at feasible costs

The effects of combined treatment of irradiation and heat on bacteria escherichia coli and sarcina lutea in dry condition

International Nuclear Information System (INIS)

Nikham; Hilmy, Nazly

1987-01-01

The effects of combination treatment of irradiation and heat on bacteria escherichia coli and sarcina lutea in dry condition. Investigation on the effects of combined irradiation + heat and heat + irradiation treatments have been carried out i.e. at the doses of 0; 1.0; 1.5; and 2.0 kGy with heating at 50 0 C for 10; 20; and 30 minutes on escherichia coli B/r, escherichia coli from sludge and sarcine lutea. Samples of bacteria were prepared in dry condition by using sterile fine sand as carrier. Irradiation was done in aerobic condition with RH 90% and the time range between irradiation and heating was not more than 2 hours. The results showed that the D 10 value did not give significant difference between the combined irradiation + heat, and heat + irradiation treatments for the 3 species of bacteria, compared to irradiation only (p 0.05). Doses of 1.0 and 1.5 kGy combined with heating at 50 0 C for 10 and 20 minutes gave better results compared to irradiation only. 17 refs

Testing for cross-subsidisation in the combined heat and power generation sector

DEFF Research Database (Denmark)

Amundsen, Eirik S; Andersen, Per; Jensen, Frank

2011-01-01

In this paper we examine cross-subsidisation among combined heat and power producers in Denmark.Information on stand-alone costs for heat generation allows us to empirically compare the Faulhaber tests,tests with an upper bound on stand-alone costs (the Palmer tests) and the fully distributed cos...... test (FDC). All tests indicate a substantial amount of cross-subsidisation from heat generation to power generation. It is shown that the FDC test is closer to that of the Faulhaber tests in its results than the Palmer tests. Thus as the Faulhaber tests are considered in the literature...

Combining different frequencies for electrical heating of saturated and unsaturated soil zones

Energy Technology Data Exchange (ETDEWEB)

Roland, U.; Holzer, F.; Kopinke, F.D. [Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Engineering, Leipzig (Germany)

2011-10-15

In situ electrical heating of soil was studied applying different frequencies: low-frequency energy for resistive heating and radio-frequency energy for dielectric heating. Steep temperature gradients were observed for each heating mode under the condition of the coexistence of saturated and unsaturated soil zones. By combining the two heating modes, this undesired effect can be avoided, thus allowing efficient soil remediation especially when organic phases are accumulated at the capillary fringe. A parallel application of both frequencies was demonstrated as the most suitable method to reduce temperature gradients. By using electronic filters, both electric fields can be established by only one electrode array. This innovative concept is especially applicable for optimizing thermal remediation of light non-aqueous phase liquid contaminations or realizing thermally-enhanced electrokinetic removal of heavy metals. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

The response of previously irradiated mouse skin to heat alone or combined with irradiation: influence of thermotolerance

International Nuclear Information System (INIS)

Wondergem, J.; Haveman, J.

1983-01-01

The effect of previous x-irradiation on the response to hyperthermia (44 0 C), x-irradiation, and irradiation combined with hyperthermia (43 0 C or 44 0 C) was studied in mouse foot skin. Irradiation of mice feet 90 days before, with 20 Gy, increased the subsequent response to heat alone, or combined with irradiation, as well as to irradiation alone. It had little effect on the thermal enhancement ratios for both acute and late skin reactions. Memory of the previous irradiation treatment could be masked when the temperature of the subsequent heat treatment alone, or combined with irradiation, was 44 0 C. Priming heat treatment induced resistance to a subsequent heat treatment and to a subsequent combined irradiation-heat treatment in normal as well as previously irradiated skin. When late skin reaction was considered, a larger 'memory' of the previous irradiation treatment was always evident, compared to acute skin reaction: the 'remembered' dose in the late skin reaction was about twice the 'remembered' dose in the acute reaction. (U.K.)

Safety analysis of coupling system of hybrid (MED-RO) nuclear desalination system utilising waste heat from HTGR

International Nuclear Information System (INIS)

Raha, Abhijit; Kishore, G.; Rao, I.S.; Adak, A.K.; Srivastava, V.K.; Prabhakar, S.; Tewari, P.K.

2010-01-01

To meet the generation IV goals, High Temperature Gas Cooled Reactors (HTGRs) are designed to have relatively higher thermal efficiency and enhanced safety and environmental characteristics. It can provide energy for combined production of hydrogen, electricity and other industrial applications. The waste heat available in the HTGR power cycle can also be utilized for the desalination of seawater for producing potable water. Desalination is an energy intensive process, so use of waste heat from HTGR certainly makes desalination process more affordable to create fresh water resources. So design of the coupling system, as per the safety design requirement of nuclear desalination plant, of desalination plant with HTGR is very crucial. In the first part of this paper, design of the coupling system between hybrid Multi Effect Desalination-Reverse Osmosis (MED-RO) nuclear desalination plant and HTGR to utilize the waste heat in HTGR are discussed. In the next part deterministic safety analysis of the designed coupling system of are presented in detail. It was found that all the coupling system meets the acceptance criteria for all the Postulated Initiating Events (PIE's) limited to DBA. (author)

Floor heating and cooling combined with displacement ventilation: Possibilities and limitations

Energy Technology Data Exchange (ETDEWEB)

Causone, Francesco; Corgnati, Stefano P. [TEBE Research Group, Department of Energetics, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Baldin, Fabio [Department of Applied Physics, University of Padova, via Venezia 1, 35131 Padova (Italy); Olesen, Bjarne W. [ICIEE, Department of Civil Engineering, Technical University of Denmark, Nils Koppels Alle Building 402, 2800 Kgs. Lyngby (Denmark)

2010-12-15

Design guidelines envisage that floor heating can be used together with displacement ventilation (DV), provided that the supply air is not overly heated before it can reach heat and contaminant sources. If this is not controlled a mixing flow pattern could occur in the room. The use of floor cooling with DV is also considered possible, although draught risk at ankle level and vertical air temperature differences must be controlled carefully, because they could increase. Few studies on these topics were found in the literature. An indoor environmental chamber was set up to obtain measurements aimed at analysing the possibilities and limitations of combining floor heating/cooling with DV. Air temperature profiles, air velocity profiles, surface temperatures and ventilation effectiveness were measured under different environmental conditions that may occur in practice. These values were compared to equivalent temperature measurements obtained using a thermal manikin. The measurements show that floor heating can be used with DV, obtaining high ventilation effectiveness values. A correlation between the floor heating capacity and the air temperature profile in the room was found. Measurements showed that floor cooling does not increase draught risk at ankle level, although it does increase vertical air temperature differences. (author)

Heat exchanger network retrofit optimization involving heat transfer enhancement

International Nuclear Information System (INIS)

Wang Yufei; Smith, Robin; Kim, Jin-Kuk

2012-01-01

Heat exchanger network retrofit plays an important role in energy saving in process industry. Many design methods for the retrofit of heat exchanger networks have been proposed during the last three decades. Conventional retrofit methods rely heavily on topology modifications which often result in a long retrofit duration and high initial costs. Moreover, the addition of extra surface area to the heat exchanger can prove difficult due to topology, safety and downtime constraints. Both of these problems can be avoided through the use of heat transfer enhancement in heat exchanger network retrofit. This paper presents a novel design approach to solve heat exchanger network retrofit problems based on heat transfer enhancement. An optimisation method based on simulated annealing has been developed to find the appropriate heat exchangers to be enhanced and to calculate the level of enhancement required. The physical insight of enhanced exchangers is also analysed. The new methodology allows several possible retrofit strategies using different retrofit methods be determined. Comparison of these retrofit strategies demonstrates that retrofit modification duration and payback time are reduced when heat transfer enhancement is utilised. Heat transfer enhancement can be also used as a substitute for increased heat exchanger network surface area to reduce retrofit investment costs.

Comparative emergency department resource utilisation across age groups.

Science.gov (United States)

Burkett, Ellen; Martin-Khan, Melinda G; Gray, Leonard C

2017-12-11

Objectives The aim of the present study was to assess comparative emergency department (ED) resource utilisation across age groups. Methods A retrospective analysis of data collected in the National Non-admitted Patient Emergency Department Care Database was undertaken to assess comparative ED resource utilisation across six age groups (0-14, 15-35, 36-64, 65-74, 75-84 and ≥85 years) with previously used surrogate markers of ED resource utilisation. Results Older people had significantly higher resource utilisation for their individual ED episodes of care than younger people, with the effect increasing with advancing age. Conclusion With ED care of older people demonstrated to be more resource intensive than care for younger people, the projected increase in older person presentations anticipated with population aging will have a magnified effect on ED services. These predicted changes in demand for ED care will only be able to be optimally managed if Australian health policy, ED funding instruments and ED models of care are adjusted to take into account the specific care and resource needs of older people. What is known about the topic? Current Australian ED funding models do not adjust for patient age. Several regional studies have suggested higher resource utilisation of ED patients aged ≥65 years. Anticipated rapid population aging mandates that contribution of age to ED visit resource utilisation be further explored. What does this paper add? The present study of national Australian ED presentations compared ED resource utilisation across age groups using surrogate markers of ED cost. Older people were found to have significantly higher resource utilisation in the ED, with the effect increasing further with advancing age. What are the implications for practitioners? The higher resource utilisation of older people in the ED warrants a review of current ED funding models to ensure that they will continue to meet the needs of an aging population.

Combined heat and power in industry and buildings

International Nuclear Information System (INIS)

Hinnells, Mark

2008-01-01

Combined heat and power (CHP) has huge potential to deliver energy savings and emissions reductions, and in many cases cost reductions too. But the market and regulatory framework is the key to delivering large-scale installations, and government has a poor record in delivering an appropriate framework. Technology is central to the future competitiveness and therefore uptake of CHP. It could lead to more efficient CHP electricity generation, permit the use of lower-carbon, renewable fuels, and enable the development of new products for new end uses, including micro-CHP and CHP in heat networks. The market for CHP has been difficult in the past few years, largely as a result of government market reforms. The UK's level of CHP skills, for installing current technologies and developing new ones, is low. The key issue is the creation of the right market framework to deliver CHP, and part of this is support for the energy services approach

Combining several thermal indices to generate a unique heat comfort assessment methodology

Directory of Open Access Journals (Sweden)

Wissam EL Hachem

2015-11-01

Full Text Available Purpose: The proposed methodology hopes to provide a systematic multi-disciplinary approach to assess the thermal environment while minimizing unneeded efforts. Design/methodology/approach: Different factors affect the perception of the human thermal experience: metabolic rate (biology, surrounding temperatures (heat balance and environmental factors and cognitive treatment (physiology.This paper proposes a combination of different multidisciplinary variables to generate a unique heat comfort assessment methodology. The variables at stake are physiological, biological, and environmental. Our own heat analysis is thoroughly presented and all relevant equations are described. Findings: Most companies are oblivious about potential dangers of heat stress accidents and thus about methods to monitor and prevent them. This methodology enables the company or the concerned individual to conduct a preliminary assessment with minimal wasted resources and time in unnecessary steps whilst providing a guideline for a detailed study with minimal error rates if needed. More so, thermal comfort is an integral part of sound ergonomics practices, which in turn are decisive for the success of any lean six sigma initiative. Research limitations/implications: This methodology requires several full implementations to finalize its design. Originality/value: Most used heat comfort models are inherently uncertain and tiresome to apply. An extensive literature review confirms the need for a uniform assessment methodology that combines the different thermal comfort models such as the Fanger comfort model (PMV, PPD and WGBT since high error rates coupled with tiresome calculations often hinder the thermal assessment process.

Drought stress had a predominant effect over heat stress on three tomato cultivars subjected to combined

DEFF Research Database (Denmark)

Zhou, Rong; Yu, Xiaqing; Ottosen, Carl-Otto

2017-01-01

and relative water content of all cultivars significantly decreased under drought and combined stress as compared to control. The net photosynthesis and starch content were significantly lower under drought and combined stress than control in the three cultivars. Stomata and pore length of the three cultivars......BACKGROUND: Abiotic stresses due to environmental factors could adversely affect the growth and development of crops. Among the abiotic stresses, drought and heat stress are two critical threats to crop growth and sustainable agriculture worldwide. Considering global climate change, incidence...... of combined drought and heat stress is likely to increase. The aim of this study was to shed light on plant growth performance and leaf physiology of three tomatoes cultivars ('Arvento', 'LA1994' and 'LA2093') under control, drought, heat and combined stress. RESULTS: Shoot fresh and dry weight, leaf area...

Heat-radiation combination for control of mold infection in harvested fruits and processed cereal foods

International Nuclear Information System (INIS)

Pawdal-Desai, S.R.; Ghanekar, A.S.; Thomas, P.; Sreenivasan, A.

1973-01-01

A combination of mild heat and low dose irradiation was found to extend the shelf-life of fresh fruits and processed cereal foods by controlling mold infection. Chapaties (Indian unleavened bread) and bread slices packed in polycell pouches, subjected to 50 krad followed by dry heat (65 0 C) were free from mold and shelf-stable for 10 weeks at ambient temperature (28-32 0 C). Inoculated pack studies confirmed the efficiency of the treatment. No immediate changes in organoleptic attributes were discernible even after exposure to 100 krad. The quality deterioration in sliced bread stored for 2 1/2 months has been attributed to natural staling rather than radiation. Hot water dip (50 0 C for 5 min) followed by 150 krad irradiation extended the shelf-life of fresh figs by 3-4 days at 28-32 0 C and 8-10 days at 15 0 C. Regardless of the sequence of treatments, combination of heat and 100 krad extended the shelf-life of grapes both at ambinet and refrigerated storage. In mangoes, heat followed by 50 krad was effective in controlling anthracnose and stem-end rot whereas in bananas irradiated for delayed ripening, hot water treatment can be used as a supplementary process to control stem-end rot. Quality of combination treated fruits was comparable to normally ripened fruits. In vitro studies with fungal pathogens isolated from the above fruits and cereal foods revealed that the synergistic effect of heat-radiation combination depends on the sequence of treatments which varied with respect to different pathogens studied. Some biochemical aspects of combination treated fruits is discussed. (F.J.)

Combined heat pump for sanitary hot water and space heating with CO{sub 2} as refrigerant; Kombineret brugsvands- og rumvarmepumpe med CO{sub 2} som koelemiddel

Energy Technology Data Exchange (ETDEWEB)

Schoen Poulsen, C. [Teknologisk Institut (Denmark)

2006-05-19

This project report describes the implementation of the Danish project called 'Combined heat pump for sanitary hot water and space heating with CO{sub 2} as refrigerant'. In the course of the project, a combined heat pump has been developed for heating sanitary hot water and producing domestic space heating. The project shows that CO2 has excellent properties in systems where a high temperature is desired on the gas cooler side and that it is possible to combine the production of sanitary hot water with the production of domestic space heating. During the project, a number of system solutions have been analysed and at the end of the project a prototype was built. It was tested in the laboratory according to a current Dutch standard for heat pumps for sanitary hot water. The prototype was constructed without the space heat part which solely has been analysed according to calculations. The reason is that there currently are no applicable European standards for the testing of combined systems and as the total efficiency of the system mainly depends on the temperature out of the gas cooler it was decided not to spend resources on the construction of the combined system in the prototype version of the unit. Instead, a number of proposals have been submitted to how the system with a space heat section could be constructed. The main components used in the prototype (compressor, exchangers, valve, control and tank) are all partly commercially available and therefore focus has been on the system construction. During the project, a number of CFD calculations have been carried out on the gas cooler in the hot water tank and the results show how important it is that the gas cooler is designed and placed correctly. The laboratory tests carried out on the unit show that the COP of the heat pump plant in connection with sanitary hot water tapping (according to Dutch standard) is 1.4 1.5 which is not immediately satisfactory. But when it is considered that the unit is a

Energy Optimization for Transcritical CO2 Heat Pump for Combined Heating and Cooling and Thermal Storage Applications

DEFF Research Database (Denmark)

Do Carmo, Carolina Madeira Ramos; Blarke, Morten; Yazawa, Kazuaki

2012-01-01

A transcritical heat pump (THP) cycle using carbon dioxide (CO2) as the refrigerant is known to feature an excellent coefficient of performance (COP) as a thermodynamic system. Using this feature, we are designing and building a system that combines a water-to-water CO2 heat pump with both hot....... The usability and the cost effectiveness are critical for smart grid policies on large-scale integration of intermittent renewables. In this paper, we present an analytic thermodynamic model that predicts the effect of temperature and flow rate of hot and cold water circulation on system COP. The analytical...

Exergy costing for energy saving in combined heating and cooling applications

International Nuclear Information System (INIS)

Nguyen, Chan; Veje, Christian T.; Willatzen, Morten; Andersen, Peer

2014-01-01

Highlights: • We investigate the basis for cost apportioning of simultaneous heating and cooling. • Two thermoeconomic methods based on energy and exergy costing is demonstrated. • The unit cost of heating and cooling for a heat pump system is found and compared. • Energy costing may obstruct efficient use of energy. • Exergy costing provides the most rational cost apportioning for energy saving. - Abstract: The aim of this study is to provide a price model that motivates energy saving for a combined district heating and cooling system. A novel analysis using two thermoeconomic methods for apportioning the costs to heating and cooling provided simultaneously by an ammonia heat pump is demonstrated. In the first method, referred to as energy costing, a conventional thermoeconomic analysis is used. Here the ammonia heat pump is subject to a thermodynamic analysis with mass and energy balance equations. In the second method referred to as exergy costing, an exergy based economic analysis is used, where exergy balance equations are used in conjunction with mass and energy balance equations. In both costing methods the thermodynamic analysis is followed by an economic analysis which includes investment and operating costs. For both methods the unit costs of heating and cooling are found and compared. The analysis shows that the two methods yield significantly different results. Rather surprisingly, it is demonstrated that the exergy costing method results in about three times higher unit cost for heating than for cooling as opposed to equal unit costs when using the energy method. Further the exergy-based cost for heating changes considerably with the heating temperature while that of cooling is much less affected

Evaluating combined effect of noise and heat on blood pressure changes among males in climatic chamber.

Science.gov (United States)

Dehghan, Habibollah; Bastami, Mohamad Taghi; Mahaki, Behzad

2017-01-01

Exposure to noise and heat causes individuals to experience some changes in the function of cardiovascular system in workplaces. This study aimed to find the combined effect of heat and noise on systolic and diastolic types of blood pressure in experimentally controlled conditions. This quasi-experimental study was performed with 12 male students in a climatic chamber in 2014. Blood pressure including systolic and diastolic was measured in the following conditions: 15 min after rest in exposure to heat (40°C, relative humidity [RH]: 30%), exposure to noise with 75, 85, and 95 dB rates in thermal comfort condition (22.1 ± 0.9 wet-bulb globe temperature), and combined exposure to heat (40°C, RH: 30%) and noise with 75, 85, and 95 dB. Friedman test was used to analyze the data. The mean change of systolic blood pressure was different significantly before and after exposure to heat and noise levels including 75, 85, and 95 dB ( P = 0.015, P = 0.001, P > 0.001, P = 0.027, respectively). Although systolic and diastolic blood pressures changed drastically, it was not significantly different in simultaneous exposure to heat and noise. Both systolic and diastolic blood pressures decreased in exposure to heat, while exposure to different levels of noise elevates systolic and diastolic blood pressures. However, when exposed to a combination of heat and noise, subtle changes of blood pressure were traced, which can be characterized as average, considering heat-only and noise-only tension situations.

Simultaneous heat and moisture transfer in soils combined with building simulation

Energy Technology Data Exchange (ETDEWEB)

Santos, G. H. dos; Mendes, N. [Pontifical Catholic University of Parana, PUCPR/CCET, Thermal Systems Laboratory (LST), Curitiba (Brazil)

2006-07-01

In order to precisely predict ground heat transfer, room air temperature and humidity, a combined model has been developed and conceived to calculate both the coupled heat and moisture transfer in soil and floor and the psychrometrics condition of indoor air. The present methodology for the soil is based on the theory of Philip and De Vries, using variable thermophysical properties for different materials. The governing equations were discretized using the finite-volume method and a three-dimensional model for describing the physical phenomena of heat and mass transfer in unsaturated moist porous soils and floor. Additionally, a lumped transient approach for a building room and a finite-volume multi-layer model for the building envelope have been developed to integrate with the soil model. Results are presented in terms of temperature, humidity and heat flux at the interface between room air and the floor, showing the importance of the approach presented and the model robustness for long-term simulations with a high time step. (author)

Waste heat recovery system

International Nuclear Information System (INIS)

Phi Wah Tooi

2010-01-01

Full text: The Konzen in-house designed anaerobic digester system for the POME (Palm Oil Mill Effluent) treatment process is one of the registered Clean Development Mechanism (CDM) projects in Malaysia. It is an organic wastewater treatment process which achieves excellent co-benefits objectives through the prevention of water pollution and reduction of greenhouse gas emissions, which is estimated to be 40,000 to 50,000 t-CO 2 per year. The anaerobic digester was designed in mesophile mode with temperature ranging from 37 degree Celsius to 45 degree Celsius. A microorganisms growth is optimum under moderately warm temperature conditions. The operating temperature of the anaerobic digester needs to be maintained constantly. There are two waste heat recovery systems designed to make the treatment process self-sustaining. The heat recovered will be utilised as a clean energy source to heat up the anaerobic digester indirectly. The first design for the waste heat recovery system utilises heat generated from the flue gas of the biogas flaring system. A stainless steel water tank with an internal water layer is installed at the top level of the flare stack. The circulating water is heated by the methane enriched biogas combustion process. The second design utilizes heat generated during the compression process for the biogas compressor operation. The compressed biogas needs to be cooled before being recycled back into the digester tank for mixing purposes. Both the waste heat recovery systems use a design which applies a common water circulation loop and hot water tank to effectively become a closed loop. The hot water tank will perform both storage and temperature buffer functions. The hot water is then used to heat up recycled sludge from 30 degree Celsius to 45 degree Celsius with the maximum temperature setting at 50 degree Celsius. The recycled sludge line temperature will be measured and monitored by a temperature sensor and transmitter, which will activate the

A new multi-objective reserve constrained combined heat and power dynamic economic emission dispatch

International Nuclear Information System (INIS)

Niknam, Taher; Azizipanah-Abarghooee, Rasoul; Roosta, Alireza; Amiri, Babak

2012-01-01

Combined heat and power units are playing an ever increasing role in conventional power stations due to advantages such as reduced emissions and operational cost savings. This paper investigates a more practical formulation of the complex non-convex, non-smooth and non-linear multi-objective dynamic economic emission dispatch that incorporates combined heat and power units. Integrating these types of units, and their power ramp constraints, require an efficient tool to cope with the joint characteristics of power and heat. Unlike previous approaches, the spinning reserve requirements of this system are clearly formulated in the problem. In this way, a new multi-objective optimisation based on an enhanced firefly algorithm is proposed to achieve a set of non-dominated (Pareto-optimal) solutions. A new tuning parameter based on a chaotic mechanism and novel self adaptive probabilistic mutation strategies are used to improve the overall performance of the algorithm. The numerical results demonstrate how the proposed framework was applied in real time studies. -- Highlights: ► Investigate a practical formulation of the DEED (Dynamic Economic Emission Dispatch). ► Consider combined heat and power units. ► Consider power ramp constraints. ► Consider the system spinning reserve requirements. ► Present a new multi-objective optimization firefly.

High-Efficiency Small-Scale Combined Heat and Power Organic Binary Rankine Cycles

OpenAIRE

Costante Mario Invernizzi; Nadeem Ahmed Sheikh

2018-01-01

Small-CHP (Combined Heat and Power) systems are generally considered a valuable technological option to the conventional boilers, in a technology developed context. If small-CHP systems are associated with the use of renewable energies (biomass, for example) they could play an important role in distributed generation even in developing countries or, in any case, where there are no extensive electricity networks. Traditionally the considered heat engines for micro- or mini-CHP are: the gas eng...

The Heat Transfer Coefficient of Recycled Concrete Bricks Combination with EPS Insulation Board Wall

Directory of Open Access Journals (Sweden)

Jianhua Li

2015-01-01

Full Text Available Four tectonic forms samples were conducted to test their heat transfer coefficients. By analyzing and comparing the test values and theoretical values of the heat transfer coefficient, a corrected-value calculation method for determining the heat transfer coefficient was proposed; the proposed method was proved to be reasonably correct. The results indicated that the recycled concrete brick wall heat transfer coefficient is higher than that of the clay brick wall, the heat transfer coefficient of recycled concrete brick wall could be effectively reduced when combined with the EPS insulation board, and the sandwich insulation type was better than that of external thermal insulation type.

Heat Transfer Analogies

Energy Technology Data Exchange (ETDEWEB)

Bhattacharyya, A

1965-11-15

This report contains descriptions of various analogues utilised to study different steady-state and unsteady-state heat transfer problems. The analogues covered are as follows: 1 . Hydraulic: a) water flow b) air flow 2. Membrane 3. Geometric Electrical: a) Electrolytic-tank b) Conducting sheet 4. Network; a) Resistance b) R-C A comparison of the different analogues is presented in the form of a table.

Heat Transfer Analogies

International Nuclear Information System (INIS)

Bhattacharyya, A.

1965-11-01

This report contains descriptions of various analogues utilised to study different steady-state and unsteady-state heat transfer problems. The analogues covered are as follows: 1 . Hydraulic: a) water flow b) air flow 2. Membrane 3. Geometric Electrical: a) Electrolytic-tank b) Conducting sheet 4. Network; a) Resistance b) R-C A comparison of the different analogues is presented in the form of a table

Rational bioenergy utilisation in energy systems and impacts on CO{sub 2} emissions

Energy Technology Data Exchange (ETDEWEB)

Wahlund, Bertil

2003-04-01

only limited emissions of CO{sub 2}. Bioenergy utilisation has additional features for environmental improvement, apart from the CO{sub 2} aspect. Waste heat from biofuel-based CHP can be cost-effectively used in conjunction with sewage treatment. The incoming sewage water to the nitrification process can be preheated with the waste heat, and thereby substantially enhance the nitrification and the reduction of ammonium nitrogen during the winter season.

Large Combined Heat and Power Plants for Sustainable Energy System

DEFF Research Database (Denmark)

Lund, Rasmus Søgaard; Mathiesen, Brian Vad

. CHP (combined heat and power) plants in Denmark will change their role from base load production to balancing the fluctuation in renewable energy supply, such as wind power and at the same time they have to change to renewable energy sources. Some solutions are already being planned by utilities...... in Denmark; conversion of pulverised fuel plants from coal to wood pellets and a circulating fluidised bed (CFB) plant for wood chips. From scientific research projects another solution is suggested as the most feasible; the combined cycle gas turbine (CCGT) plant. In this study a four scenarios...

Some technological aspects of combined processing of meat by heat and ionizing radiations

International Nuclear Information System (INIS)

Gel'fand, S.Yu.; Nomenotskaya, N.F.; Mozul', M.Ya.

1974-01-01

The paper discusses the use of ionizing radiation to prolong the storage life of meat and meat products. Irradiating raw meat with doses of 0.4-0.6 Mrad increased storage life up to two months at low above-zero C temperatures. The difficulty of inhibiting autolytic processes during storage of irradiated raw meat led to searches for combined methods of meat treatment. A series of experiments was staged with pre-irradiation heating of meat up to 75, 77, and 80 0 C in order to see how cathepsin activity is affected by the duration and temperature of heating in the case of combined treatment. To increase the resistance of meat products to microbial damage, tests were carried out in which meat was exposed to short-term but intensive heat by immersing it in hot (130-160 0 C) vegetable oil (frying grease). The results are presented in the form of tables and diagrams. (E.T.)

City/industry/utility partnership leads to innovative combined heat and power project

Energy Technology Data Exchange (ETDEWEB)

Savage, J. [Savage and Associates, Quesnel, BC (Canada)

2010-07-01

This presentation discussed a combined heat and power (CHP) project that was launched in Quesnel, British Columbia. The CHP is being developed in phases in which new components will enter the system, providing added benefits. Hot oil from a sawmill bioenergy system will be used to heat lumber kilns, generate electricity at an Organic Rankine Cycle co-generation plant, and heat water for a District Energy Loop (DEL) to heat up to 22 existing buildings in the city as well as sawmill and planer buildings. The DEL piping would comprise a 5 kilometre loop. The energy would come from recovered sawmill space heating, recovered stack energy, and additional biomass energy. All of the district heating and 41 per cent of the power would be from heat recovered from the existing industrial operation. This bio-economy vision ultimately involves incorporating a biogas digester into the system to process food, regional organic waste, and pulp mill residuals, relying on bio-solids and heat from the mill. The fertilizer from the digester would then be used in a biomass plantation, which would provide materials to industry for many products, including bio-refining. This project evolved in response to concerns about the ecological effects and long-term economics of aggressive utilization of forest biomass. 15 figs.

Heat of fusion storage systems for combined solar systems in low energy buildings

DEFF Research Database (Denmark)

Schultz, Jørgen Munthe; Furbo, Simon

2004-01-01

Solar heating systems for combined domestic hot water and space heating has a large potential especially in low energy houses where it is possible to take full advantage of low temperature heating systems. If a building integrated heating system is used – e.g. floor heating - the supply temperature...... from solid to liquid form (Fig. 1). Keeping the temperature as low as possible is an efficient way to reduce the heat loss from the storage. Furthermore, the PCM storage might be smaller than the equivalent water storage as more energy can be stored per volume. If the PCM further has the possibility...... systems through further improvement of water based storages and in parallel to investigate the potential of using storage designs with phase change materials, PCM. The advantage of phase change materials is that large amounts of energy can be stored without temperature increase when the material is going...

Satellite combined heat and power plants and their legal autonomy; Satelliten-BHKW und deren rechtliche Eigenstaendigkeit

Energy Technology Data Exchange (ETDEWEB)

Loibl, Helmut [Kanzlei Paluka Sobola Loibl und Partner, Regensburg (Germany). Abt. Erneuerbare Energien

2014-04-15

Since the landmark decision by the German Court of Justice concerning the term ''plant'' in the context of biogas plants it should be clear beyond doubt that satellite combined heat and power plants (CHPs) are legally autonomous plants pursuant to Para. 3 No. 1 of the Renewable Energy Law (EEG). What has yet to be finally resolved are the conditions under which satellite CHPs are to be regarded as autonomous. This will be a question of distance on the one hand and of operation autonomy on the other. In the individual case both these factors will have to be assessed from the perspective of an average objective, informed citizen. To the extent that its heat and electricity are being utilised in a meaningful manner, the plant's autonomy will be beyond doubt, at least in operational terms. Regarding the remuneration to be paid for satellite CHPs the only case requiring special consideration is when a CHP falls under the EEG of 2012. In this case Para. 1 Section 1 Sentence 2 EEG provides that the remuneration for the CHP in question is to be calculated as if there was a single overall plant. To the extent that none of the CHPs fall under the EEG of 2012, the ruling remains that there is a separate entitlement to remuneration for each satellite CHP. This also holds in cases where satellite CHPs that were commissioned after 1 January 2012 are relocated. When a satellite CHP is replaced by a new one, the rate and duration of remuneration remain unchanged. However, when a new satellite CHP is added to an existing satellite CHP via a gas collector line it is to be treated according to the decisions of the Federal Court of Justice concerning biogas plant extensions: It falls under the law that applies to the existing CHP and has an entitlement to a new minimum remuneration period, albeit subject to the degression rate provided by the EEG version in question.

Extensive utilisation of VR-1 reactor for nuclear education and training

International Nuclear Information System (INIS)

Rataj, J.

2010-01-01

The paper presents utilisation of the VR-1 reactor for nuclear education and training at national and international level. VR-1 reactor has been operating by the Czech Technical University since December 1990. The reactor is a pool-type light water reactor based on enriched uranium (19.7% 235 U) with maximum thermal power 1kW and for short time period up to 5kW. The moderator of neutrons is light water, which is also used as a reflector, a biological shielding and a coolant. Heat is removed from the core by natural convection. The pool disposition of the reactor facilitates access to the core, setting and removing of various experimental samples and detectors, easy and safe handling of fuel assemblies. The reactor core can contain from 17 to 21 fuel assemblies IRT-4M, depending on the geometric arrangement and kind of experiments to be performed in the reactor. The reactor is equipped with several experimental devices; e.g. horizontal, radial and tangential channels used to take out a neutron beam, reactivity oscillator for dynamics study and bubble boiling simulator. The reactor has been used very efficiently especially for education and training of university students and NPP's specialists for more than 18 years. The VR-1 reactor is utilised within various national and international activities such as Czech Nuclear Education Network (CENEN), European Nuclear Education Network and also Eastern European Research Reactor Initiative (EERRI). The reactor is well equipped for education and training not only by the experimental facility itself but also by incessant development of training methods and improvement of education experiments. The education experiments can be combined into training courses attended by students according to their study specialization and knowledge level. The training programme is aimed to the reactor and neutron physics, dosimetry, nuclear safety, and control of nuclear installations. Every year, approximately 250 university students undergo

Study of a molten carbonate fuel cell combined heat, hydrogen and power system: Energy analysis

International Nuclear Information System (INIS)

Agll, Abdulhakim Amer A.; Hamad, Yousif M.; Hamad, Tarek A.; Thomas, Mathew; Bapat, Sushrut; Martin, Kevin B.; Sheffield, John W.

2013-01-01

Countries around the world are trying to use alternative fuels and renewable energy to reduce the energy consumption and greenhouse gas emissions. Biogas contains methane is considered a potential source of clean renewable energy. This paper discusses the design of a combined heat, hydrogen and power system, which generated by methane with use of Fuelcell, for the campus of Missouri University of Science and Technology located in Rolla, Missouri, USA. An energy flow and resource availability study was performed to identify sustainable type and source of feedstock needed to run the Fuelcell at its maximum capacity. FuelCell Energy's DFC1500 unit (a molten carbonate Fuelcell) was selected as the Fuelcell for the tri-generation (heat, hydrogen and electric power) system. This tri-generation system provides electric power to the campus, thermal energy for heating the anaerobic digester, and hydrogen for transportation, backup power and other applications on the campus. In conclusion, the combined heat, hydrogen and power system reduces fossil fuel usage, and greenhouse gas emissions at the university campus. -- Highlights: • Combined heat, hydrogen and power (CHHP) using a molten carbonate fuel cell. • Energy saving and alternative fuel of the products are determined. • Energy saving is increased when CHHP technology is implemented. • CHHP system reduces the greenhouse gas emissions and fuel consumption

Carbon Emissions Trading and Combined Heat and Power Strategies: Unintended Consequences

Science.gov (United States)

Tysseling, John C.; Vosevich, Mary; Boersma, Benjamin R.; Zumwalt, Jefferey A.

2009-01-01

Facility professionals continuously search for projects that reduce energy consumption and operating costs so as to directly benefit their bottom line. Many institutions nationwide have contemplated or made investments in combined heat and power (CHP) projects as a life-cycle strategy to minimize operating costs. However, recent sustainability and…

A new desalination system using a combination of heat pipe, evacuated tube and parabolic trough collector

International Nuclear Information System (INIS)

Jafari Mosleh, H.; Jahangiri Mamouri, S.; Shafii, M.B.; Hakim Sima, A.

2015-01-01

Highlights: • A new desalination uses a combination of heat pipe and parabolic trough collector. • A twin-glass evacuated tube is used to decrease the thermal losses from heat pipe. • Adding oil into the space between heat pipe and tube collector enhances the yield. • The yield and efficiency reach up to 0.933 kg/(m 2 h) and 65.2%, respectively. - Abstract: The solar collectors have been commonly used in desalination systems. Recent investigations show that the use of a linear parabolic trough collector in solar stills can improve the efficiency of a desalination system. In this work, a combination of a heat pipe and a twin-glass evacuated tube collector is utilized with a parabolic trough collector. Results show that the rate of production and efficiency can reach to 0.27 kg/(m 2 h) and 22.1% when aluminum conducting foils are used in the space between the heat pipe and the twin-glass evacuated tube collector to transfer heat from the tube collector to the heat pipe. When oil is used as a medium for the transfer of heat, filling the space between heat pipe and twin-glass evacuated tube collector, the production and efficiency can increase to 0.933 kg/(m 2 h) and 65.2%, respectively

Biomass gasification to heat, electricity and biofuels. HighBio project publication

Energy Technology Data Exchange (ETDEWEB)

Lassi, U.; Wikman, B. (eds.)

2011-07-01

Renewable energy and the use of biomass in energy production promotes sustainable development and decreases the use of fossil fuels. Biomass, e.g. wood chips can be used in the production of heat and electricity, as well as being used as a biofuel component and novel product for the chemical industry. Efficient utilisation of biomass requires a high level of knowledge and the development of new processes to create a new way of thinking. In this process, international co-operation plays a significant role. The aim of the HighBio project was to produce new information on biomass gasification and the utilisation opportunities of product gas in biofuel and biochemicals production. The project was also aimed at studying utilisation properties of biogasification ashes in distributed energy production. Small-scaled CHP plants can be used for simultaneous heat and power production by gasifying wood chips and by burning energy intensive product gas. Compared with thermal combustion, particulate emissions from gasification are lower, which also contributes to the EU's ever tightening emission legislation. Several small and middle scale companies in the Northern part of Finland and Sweden have worked with biomass gasification, and during the project, the birth of new ones has been seen. In this development stage, researchers of the HighBio project have also been strongly involved. Increased use of renewable energy opens up new possibilities for entrepreneurship and the birth of new companies, especially in rural areas. In order to enable these opportunities, we need research data from the universities, novel innovations, and especially their successful commercialisation. The HighBio project has also contributed to tackling those challenges by arranging research seminars and meetings to companies and other interest groups, as well as by establishing research activities and collaborations. Regional collaboration combined with national and international research networks

Methods for planning and operating decentralized combined heat and power plants

Energy Technology Data Exchange (ETDEWEB)

Palsson, H.

2000-02-01

In recent years, the number of decentralized combined heat and power (DCHP) plants, which are typically located in small communities, has grown rapidly. These relatively small plants are based on Danish energy resources, mainly natural gas, and constitute an increasing part of the total energy production in Denmark. The topic of this thesis is the analysis of DCHP plants, with the purpose to optimize the operation of such plants. This involves the modelling of district heating systems, which are frequently connected to DCHP plants, as well as the use of heat storage for balancing between heat and power production. Furthermore, the accumulated effect from increasing number of DCHP plants on the total power production is considered. Methods for calculating dynamic temperature response in district heating (DH) pipes have been reviewed and analyzed numerically. Furthermore, it has been shown that a tree-structured DH network consisting of about one thousand pipes can be reduced to a simple chain structure of ten equivalent pipes without loosing much accuracy when temperature dynamics are calculated. A computationally efficient optimization method based on stochastic dynamic programming has been designed to find an optimum start-stop strategy for a DCHP plant with a heat storage. The method focuses on how to utilize heat storage in connection with CHP production. A model for the total power production in Eastern Denmark has been applied to the accumulated DCHP production. Probability production simulations have been extended from the traditional power-only analysis to include one or several heat supply areas. (au)

Combined natural convection and radiation in a volumetrically heated fluid layer

International Nuclear Information System (INIS)

Chawla, T.C.; Chan, S.H.; Cheung, F.B.; Cho, D.H.

1980-01-01

The effect of radiation in combination with turbulent natural convection on the rates of heat transfer in volumetrically heated fluid layers characterized by high temperatures has been considered in this study. It is demonstrated that even at high Rayleigh numbers the radiation mode is as effective as the turbulent natural convection mode in removing the heat from the upper surface of the molten pools with adiabatic lower boundary. As a result of this improved heat transfer, it is shown that considerably thicker molten pools with internal heat generation can be supported without boiling inception. The total Nusselt number at a moderate but fixed value of conduction-radiation parameter, can be represented as a function of Rayleigh number in a simple power-law form. As a consequence of this relationship it is shown that maximum nonboiling pool thicknesses vary approximately inversely as the 0.9% power of internal heat generation rate. A comparison between exact analysis using the integral formulation of radiation flux and Rosseland approximation shows that the latter approximation bears out very adequately for optically thick pools with conduction-radiation parameters greater than or equal to 0.4 inspite of the fact that individual components of Nusselt number due to radiation and convection, respectively, are grossly in error. These errors in component heat fluxes are compensating due to the total heat balance constraint. However, the comparison between Rosseland approximation and exact formulation gets poorer as the value of conduction-radiation parameters decreases. This increase in error is principally incurred due to the error in estimating wall temperature differences

Combined natural convection and radiation in a volumetrically heated fluid layer

International Nuclear Information System (INIS)

Chawla, T.C.; Chan, S.H.; Cheung, F.B.; Cho, D.H.

1980-01-01

The effect of radiation in combining with turbulent natural convection on the rates of heat transfer in volumetrically heated fluid layers characterized by high temperatures has been considered in this study. It is demonstrated that even at high Rayleigh numbers the radiation mode is as effective as the turbulent natural convection mode in removing the heat from the upper surface of molten pools with adiabatic lower boundary. As a result of this improved heat transfer, it is shown that considerably thicker molten pools with internal heat generation can be supported without boiling inception. The total Nusselt number at a moderate but fixed value of conduction-radiation parameter, can be represented as a function of Rayleigh number in a simple power-law form. As a consequence of this relationship it is shown that maximum nonboiling pool thicknesses vary approximately inversely as the 0.9 power of internal heat generation rate. A comparison between exact analysis using the integral formulation of radiation flux and Rosseland approximateion shows that the latter approximation bears out very adequately for optically thick pools with conduction-radiation parameter > or approx. =0.4 inspite of the fact that individual components of Nusselt number due to radiation and convection, respectively, are grossly in error. These errors in component heat fluxes are compensating due to the total heat balance constraint. However, the comparison between Rosseland approximation and exact formulation gets poorer as the value of conduction-radiation parameter decreases. This increase in error is principally incurred due to the error in estimating wall temperature differences

Combined Space and Water Heating: Next Steps to Improved Performance

Energy Technology Data Exchange (ETDEWEB)

Schoenbauer, B. [NorthernSTAR Building America Partnership, Minneapolis, MN (United States); Bohac, D. [NorthernSTAR Building America Partnership, Minneapolis, MN (United States); Huelman, P. [NorthernSTAR Building America Partnership, Minneapolis, MN (United States)

2016-07-13

A combined space- and water-heating (combi) system uses a high-efficiency direct-vent burner that eliminates safety issues associated with natural draft appliances. Past research with these systems shows that using condensing water heaters or boilers with hydronic air handling units can provide both space and water heating with efficiencies of 90% or higher. Improved controls have the potential to reduce complexity and improve upon the measured performance. This project demonstrates that controls can significantly benefit these first-generation systems. Laboratory tests and daily load/performance models showed that the set point temperature reset control produced a 2.1%-4.3% (20-40 therms/year) savings for storage and hybrid water heater combi systems operated in moderate-load homes.

Environmental assessment of incinerator residue utilisation

OpenAIRE

Toller, Susanna

2008-01-01

 In Sweden, utilisation of incinerator residues outside disposal areas is restricted by environmental concerns, as such residues commonly contain greater amounts of potentially toxic trace elements than the natural materials they replace. On the other hand, utilisation can also provide environmental benefits by decreasing the need for landfill and reducing raw material extraction. This thesis provides increased knowledge and proposes better approaches for environmental assessment of incinerat...

National energy policies: Obstructing the reduction of global CO2 emissions? An analysis of Swedish energy policies for the district heating sector

International Nuclear Information System (INIS)

Difs, Kristina

2010-01-01

The effect of national energy policies on a local Swedish district heating (DH) system has been studied, regarding the profitability of new investments and the potential for climate change mitigation. The DH system has been optimised regarding three investments: biomass-fuelled CHP (bio CHP), natural gas-fuelled combined cycle CHP (NGCC CHP) and biomass-fuelled heat-only boiler (bio HOB) in two scenarios (with or without national taxes and policy instruments). In both scenarios EU's tradable CO 2 emission permits are included. Results from the study show that when national policies are included, the most cost-effective investment option is the bio CHP technology. However, when national taxes and policy instruments are excluded, the DH system containing the NGCC CHP plant has 30% lower system cost than the bio CHP system. Regardless of the scenario and when coal condensing is considered as marginal electricity production, the NGCC CHP has the largest global CO 2 reduction potential, about 300 ktonne CO 2 . However, the CO 2 reduction potential is highly dependent on the marginal electricity production. Demonstrated here is that national policies such as tradable green certificates can, when applied to DH systems, contribute to investments that will not fully utilise the DH systems' potential for global CO 2 emissions reductions. - Research highlights: →Swedish energy policies are promoting biomass fuelled electricity generating technologies over efficient fossil fuel electricity generating technologies. →An efficient fossil fuel technology like the natural gas combine cycle CHP technology with high power-to-heat ratio has potential to reduce the global CO 2 emissions more than a biomass fuelled electricity generating technology. →Swedish energy policies such as tradable green certificates for renewable electricity can, when applied to district heating systems, contribute to investments that will not fully utilise the district heating systems potential for

Process for adapting a heat source and a thermal machine by temporary heat storage

International Nuclear Information System (INIS)

Cahn, R.P.; Nicholson, E.W.

1975-01-01

The process described is intended to ensure the efficient use of the heat from a nuclear reactor or from a furnace burning fossil fuel at constant power, and of a boiler in a power station comprising a multi-stage steam turbine, the steam extracted from the turbine being used for pre-heating the boiler feed water. This process is most flexible with a varying load. It includes the high temperature storage of the excess heat energy in a low vapor pressure storage liquid (hydrocarbon oils, molten salts or liquid metals) at atmospheric pressure when the demand is low; then, when the energy demand is at its height, the reduction of steam extraction from the turbine with simultaneous utilisation of the hot heat storage liquid for the various maintenance heating functions of the power station by heat exchange, so that the heat can expand totally in the turbine with generation of energy [fr

An analysis of partial efficiencies of energy utilisation of different macronutrients by barramundi (Lates calcarifer) shows that starch restricts protein utilisation in carnivorous fish.

Science.gov (United States)

Glencross, Brett D; Blyth, David; Bourne, Nicholas; Cheers, Susan; Irvin, Simon; Wade, Nicholas M

2017-02-01

This study examined the effect of including different dietary proportions of starch, protein and lipid, in diets balanced for digestible energy, on the utilisation efficiencies of dietary energy by barramundi (Lates calcarifer). Each diet was fed at one of three ration levels (satiety, 80 % of initial satiety and 60 % of initial satiety) for a 42-d period. Fish performance measures (weight gain, feed intake and feed conversion ratio) were all affected by dietary energy source. The efficiency of energy utilisation was significantly reduced in fish fed the starch diet relative to the other diets, but there were no significant effects between the other macronutrients. This reduction in efficiency of utilisation was derived from a multifactorial change in both protein and lipid utilisation. The rate of protein utilisation deteriorated as the amount of starch included in the diet increased. Lipid utilisation was most dramatically affected by inclusion levels of lipid in the diet, with diets low in lipid producing component lipid utilisation rates well above 1·3, which indicates substantial lipid synthesis from other energy sources. However, the energetic cost of lipid gain was as low as 0·65 kJ per kJ of lipid deposited, indicating that barramundi very efficiently store energy in the form of lipid, particularly from dietary starch energy. This study defines how the utilisation efficiency of dietary digestible energy by barramundi is influenced by the macronutrient source providing that energy, and that the inclusion of starch causes problems with protein utilisation in this species.

Micro-tubular flame-assisted fuel cells for micro-combined heat and power systems

Science.gov (United States)

Milcarek, Ryan J.; Wang, Kang; Falkenstein-Smith, Ryan L.; Ahn, Jeongmin

2016-02-01

Currently the role of fuel cells in future power generation is being examined, tested and discussed. However, implementing systems is more difficult because of sealing challenges, slow start-up and complex thermal management and fuel processing. A novel furnace system with a flame-assisted fuel cell is proposed that combines the thermal management and fuel processing systems by utilizing fuel-rich combustion. In addition, the flame-assisted fuel cell furnace is a micro-combined heat and power system, which can produce electricity for homes or businesses, providing resilience during power disruption while still providing heat. A micro-tubular solid oxide fuel cell achieves a significant performance of 430 mW cm-2 operating in a model fuel-rich exhaust stream.

Exergoeconomic performance optimization of an endoreversible intercooled regenerative Brayton combined heat and power plant coupled to variable-temperature heat reservoirs

Energy Technology Data Exchange (ETDEWEB)

Yang, Bo; Chen, Lingen; Sun, Fengrui [College of Naval Architecture and Power, Naval University of Engineering, Wuhan 430033 (China)

2012-07-01

An endoreversible intercooled regenerative Brayton combined heat and power (CHP) plant model coupled to variable-temperature heat reservoirs is established. The exergoeconomic performance of the CHP plant is investigated using finite time thermodynamics. The analytical formulae about dimensionless profit rate and exergy efficiency of the CHP plant with the heat resistance losses in the hot-, cold- and consumer-side heat exchangers, the intercooler and the regenerator are deduced. By taking the maximum profit rate as the objective, the heat conductance allocation among the five heat exchangers and the choice of intercooling pressure ratio are optimized by numerical examples, the characteristic of the optimal dimensionless profit rate versus corresponding exergy efficiency is investigated. When the optimization is performed further with respect to the total pressure ratio, a double-maximum profit rate is obtained. The effects of the design parameters on the double-maximum dimensionless profit rate and corresponding exergy efficiency, optimal total pressure ratio and optimal intercooling pressure ratio are analyzed in detail, and it is found that there exist an optimal consumer-side temperature and an optimal thermal capacitance rate matching between the working fluid and the heat reservoir, respectively, corresponding to a thrice-maximum dimensionless profit rate.

Trends, determinants and inequities of 4+ ANC utilisation in Bangladesh.

Science.gov (United States)

Rahman, Aminur; Nisha, Monjura Khatun; Begum, Tahmina; Ahmed, Sayem; Alam, Nurul; Anwar, Iqbal

2017-01-13

The objectives of this study are to document the trend on utilisation of four or more (4 + ) antenatal care (ANC) over the last 22 years period and to explore the determinants and inequity of 4 + ANC utilisation as reported by the last two Bangladesh Demographic and Health surveys (BDHS) (2011 and 2014). The data related to ANC have been extracted from the BDHS data set which is available online as an open source. STATA 13 software was used for organising and analysing the data. The outcome variable considered for this study was utilisation of 4 + ANC. Trends of 4 + ANC were measured in percentage and predictors for 4 + ANC were measured through bivariate and multivariable analysis. The concentration index was estimated for assessing inequity in 4 + ANC utilisation. Utilisation of 4 + ANC has increased by about 26% between the year 1994 and 2014. Higher level of education, residing in urban region and richest wealth quintile were found to be significant predictors. The utilisation of 4 + ANC has decreased with increasing parity and maternal age. The inequity indices showed consistent inequities in 4 + ANC utilisation, and such inequities were increased between 2011 and 2014. In Bangladesh, the utilisation of any ANC rose steadily between 1994 and 2014, but progress in terms of 4 + ANC utilisation was much slower as the expectation was to achieve the national set target (50%: 4 + ANC utilisation) by 2016. Socio-economic inequities were observed in groups that failed to attend a 4 + ANC visit. Policymakers should pay special attention to increase the 4 + ANC coverage where this study can facilitate to identify the target groups whom need to be intervened on priority basis.

CHP in Switzerland from 1990 to 1998. Thermal power generation including combined heat and power

International Nuclear Information System (INIS)

Kaufmann, U.

1999-01-01

The results of a study on thermal power generation in Switzerland show that combined heat and power (CHP) systems have grown rapidly. Statistics are presented on the development of CHP-based power and also on thermal power stations without waste heat usage. Figures are given for gas and steam turbine installations, combined gas and steam turbine stations and motor-driven CHP units. Power production is categorised, separating small and large (over 1 Megawatt electrical) power generation facilities. On-site, distributed power generation at consumers' premises and the geographical distribution of plant is described

Harmony search algorithm for solving combined heat and power economic dispatch problems

Energy Technology Data Exchange (ETDEWEB)

Khorram, Esmaile, E-mail: eskhor@aut.ac.i [Department of Applied Mathematics, Faculty of Mathematics and Computer Science, Amirkabir University of Technology, No. 424, Hafez Ave., 15914 Tehran (Iran, Islamic Republic of); Jaberipour, Majid, E-mail: Majid.Jaberipour@gmail.co [Department of Applied Mathematics, Faculty of Mathematics and Computer Science, Amirkabir University of Technology, No. 424, Hafez Ave., 15914 Tehran (Iran, Islamic Republic of)

2011-02-15

Economic dispatch (ED) is one of the key optimization problems in electric power system operation. The problem grows complex if one or more units produce both power and heat. Combined heat and power economic dispatch (CHPED) problem is a complicated problem that needs powerful methods to solve. This paper presents a harmony search (EDHS) algorithm to solve CHPED. Some standard examples are presented to demonstrate the effectiveness of this algorithm in obtaining the optimal solution. In all cases, the solutions obtained using EDHS algorithm are better than those obtained by other methods.

Modelling energy savings in the Danish building sector combined with internalisation of health related externalities in a heat and power system optimisation model

DEFF Research Database (Denmark)

Zvingilaite, Erika

2013-01-01

. Furthermore, the results suggest that changes in the energy generation sector are the prime driver behind the reduction of environmental externalities of energy. Heat savings in buildings play only a small role under model assumptions. © 2012Elsevier Ltd. All rights reserved.......A substantial untapped energy saving potential rests in the building sector and is expected to play an important role in achieving reduction of environmental impacts of energy. In order to utilise this potential, effective policy measures need to be adopted to remove the existing barriers...... and create incentives. For that purpose, the cost effective energy saving options together with an optimal level of savings and expected environmental benefits have to be identified. The paper reports on a study that analyses these questions by including heat-saving measures in buildings into an energy...

Power, heat and chilliness with natural gas - fuel cells and air conditioning

International Nuclear Information System (INIS)

Krein, Stephan; Ruehling, Karin

1999-01-01

A new and innovative concept of the supply with power, heat and chilliness will realise in the new Malteser-hospital in Kamenz. The core of this demonstration-plant are a fuel cell, an adsorption cooling machine as well as multi-solar collectors. The fuel cell has two goals. Primary it produces power for the own demand. The selected dimension guarantees, that the power will consume nearly continuously. Secondly the produced heat of the fuel cell (and the solar-heat too) will use for heating and preparation of warm water. In the summer, the heat will use for the adsorption cooling machine, which produces chilliness for air-conditioning. The advantage in the face of common concepts of combining power and heat is the high-efficiently use of the fuel-energy for electric power generation on the one hand. Fuel cells work with high efficiency also at partial load. On the other hand, with the adsorption cooling machine the produced heat of fuel cell and multi-solar collectors can be used also in the summer. First experiences with this concept show, that an optimised co-operation of the components with an adaptive, self-learning control system based on the weather forecast as well as various storages for heat and chilliness can be achieve. A continuously operation, high fuel utilisation and reduced environmental pollution can be demonstrated. (author)

Power contracting between two different partners. Biogas combined heat and power plants; Energie-Contracting zweier unterschiedlicher Partner. Biogas-Blockheizkraftwerk

Energy Technology Data Exchange (ETDEWEB)

Lennartz, Marc Wilhelm

2013-06-15

An agricultural consortium in the Eifel (Federal Republic of Germany) has adopted a comprehensive supply of a 7,000 m{sup 2} comprising hotel complex with combined heat and power. The old oil-fired central heating plant has been replaced by a biogas-powered combined heat and power plant (CHP). The hotel was directly connected to the CHP plant by means of a new, approximately 300 m long local heating network including buffer storage. Overall, the hotel operator saves approximately 300,000 L of heating oil annually. The energy demand of the hotel operator will be covered by more than 90 % by means of CHP plants. Thus 20 % of the heating costs is saved.

Combined Heat and Power Market Potential for Opportunity Fuels

Energy Technology Data Exchange (ETDEWEB)

Jones, David [Resource Dynamics Corporation, McLean, VA (United States); Lemar, Paul [Resource Dynamics Corporation, McLean, VA (United States

2015-12-01

This report estimates the potential for opportunity fuel combined heat and power (CHP) applications in the United States, and provides estimates for the technical and economic market potential compared to those included in an earlier report. An opportunity fuel is any type of fuel that is not widely used when compared to traditional fossil fuels. Opportunity fuels primarily consist of biomass fuels, industrial waste products and fossil fuel derivatives. These fuels have the potential to be an economically viable source of power generation in various CHP applications.

Efficient on-chip hotspot removal combined solution of thermoelectric cooler and mini-channel heat sink

International Nuclear Information System (INIS)

Hao, Xiaohong; Peng, Bei; Xie, Gongnan; Chen, Yi

2016-01-01

Highlights: • A combined solution of thermoelectric cooler (TEC) and mini-channel heat sink to remove the hotspot of the chip has been proposed. • The TEC's mathematical model is established to assess its work performance. • A comparative study on the proposed efficient On-Chip Hotspot Removal Combined Solution. - Abstract: Hotspot will significantly degrade the reliability and performance of the electronic equipment. The efficient removal of hotspot can make the temperature distribution uniform, and ensure the reliable operation of the electronic equipment. This study proposes a combined solution of thermoelectric cooler (TEC) and mini-channel heat sink to remove the hotspot of the chip in the electronic equipment. Firstly, The TEC's mathematical model is established to assess its work performance under different boundary conditions. Then, the hotspot removal capability of the TEC is discussed for different cooling conditions, which has shown that the combined equipment has better hotspot removal capability compared with others. Finally, A TEC is employed to investigate the hotspot removal capacity of the combined solution, and the results have indicated that it can effectively remove hotspot in the diameter of 0.5 mm, the power density of 600W/cm 2 when its working current is 3A and heat transfer thermal resistance is 0 K/W.

Price and utilisation differences for statins between four countries.

Science.gov (United States)

Thai, Loc Phuoc; Vitry, Agnes Isabelle; Moss, John Robert

2018-02-01

Australia, England, France and New Zealand use different policies to regulate their medicines market, which can impact on utilisation and price. To compare the prices and utilisation of statins in Australia, England, France and New Zealand from 2011 to 2013. Utilisation of statins in the four countries was compared using Defined Daily Doses (DDD) per 1000 inhabitants per year. Pairwise Laspeyres and Paasche index comparisons were conducted comparing the price and utilisation of statins. The results showed that the price of statins in New Zealand was the cheapest. The price of statins in Australia was most expensive in 2011 and 2012 but France was more expensive in 2013. There were large differences between the Laspeyres index and Paasche index when comparing the price and utilisation of England with Australia and France. The policies that regulate the New Zealand and England medicines markets were more effective in reducing the price of expensive statins. The relative utilisation of cheaper statins was greatest in England and had a large effect on the differences between the two index results. The pricing policies in Australia have been only partly effective in reducing the price of statins compared to other countries.

Air bottoming cycle, an alternative to combined cycles. Final report

Energy Technology Data Exchange (ETDEWEB)

Kaikko, J. [Royal Inst. of Techn., Stockholm (Sweden). Dept. of Energy Technology

2001-10-01

In this work, the idea of Air Bottoming Cycle (ABC) has been studied. The objectives for the work have been to establish an understanding of the concept for power and heat generation as well as to find - if possible - feasible concepts for future use in the Swedish energy system. Combined cycle in power generation is an established technology. In the conventional combined cycle, a gas turbine works as a topping cycle together with the steam (Rankine) bottoming cycle. In the ABC the steam bottoming cycle is replaced with a gas turbine (Brayton) bottoming cycle having air as a working fluid. The two gas turbines are thermally connected over a gas-to-gas heat exchanger. This concept promises savings in weight and cost, as well as operating benefits, compared to the Rankine bottoming technology. The ABC has been modelled using a heat balance program, and a parametric study for the concept optimisation as well as for off-design analysis has been performed. Performance of the ABC has been compared to other, established technologies. A preliminary economic evaluation has been made. As a result of the study, it is clarified that the Rankine bottoming cycle with steam remains superior to the ABC as regards electrical efficiency in the medium and large power scale. For small-scale applications (<10 MW{sub e}) where the thermodynamic advantage of the Rankine cycle is not dominating any longer and its economy is burdened by the heavy investment structure, the ABC becomes the better alternative for energy utilisation. A preliminary economic evaluation shows that (at energy prices autumn 2000) the ABC is at the same level as the comparable small-scale cogeneration installations. Due to high power-to-heat ratio however, higher electricity prices will favour the ABC. One interesting feature of the ABC is that about 50% of the dissipated low-value heat from the cycle is carried by clean (sterile) air at the temperature around 200 deg C. This air can be utilised for space heating or

Optimal Operation of Network-Connected Combined Heat and Powers for Customer Profit Maximization

Directory of Open Access Journals (Sweden)

Da Xie

2016-06-01

Full Text Available Network-connected combined heat and powers (CHPs, owned by a community, can export surplus heat and electricity to corresponding heat and electric networks after community loads are satisfied. This paper proposes a new optimization model for network-connected CHP operation. Both CHPs’ overall efficiency and heat to electricity ratio (HTER are assumed to vary with loading levels. Based on different energy flow scenarios where heat and electricity are exported to the network from the community or imported, four profit models are established accordingly. They reflect the different relationships between CHP energy supply and community load demand across time. A discrete optimization model is then developed to maximize the profit for the community. The models are derived from the intervals determined by the daily operation modes of CHP and real-time buying and selling prices of heat, electricity and natural gas. By demonstrating the proposed models on a 1 MW network-connected CHP, results show that the community profits are maximized in energy markets. Thus, the proposed optimization approach can help customers to devise optimal CHP operating strategies for maximizing benefits.

Current and future prospects for heat recovery from waste in European district heating systems: A literature and data review

DEFF Research Database (Denmark)

Persson, Urban; Münster, Marie

2016-01-01

Municipal solid waste has seen increasing annual volumes for many decades in contemporary Europe and constitutes, if not properly managed, an environmental problem due to local pollution and greenhouse gas emissions. From an energy perspective, waste is also an alternative fuel for power and heat...... to establish and assess current and future EU (European Union) waste generation and management. Main conclusions are that more heat can be recovered from current Waste-to-Energy facilities operating at low average heat recovery efficiencies, that efficient incineration capacity is geographically concentrated...... heat distribution infrastructures, without which no large-scale recovery and utilisation of excess heat is possible. In this paper, which aims to estimate municipal solid waste volumes available for heat recovery in European district heating systems in 2030, a literature and data review is performed...

Physiological and metabolic changes of purslane (Portulaca oleracea L. in response to drought, heat and combined stresses

Directory of Open Access Journals (Sweden)

Rui eJin

2016-01-01

Full Text Available Purslane (Portulaca oleracea L. is a fleshy herbaceous plant. So far, little information is available on the response of this plant to combined drought and heat stress. In this study, changes in physiological and metabolic levels were characterized after treatments with drought, heat and combined stresses. Both individual and combined stress treatments increased malondialdehyde (MDA, electrolyte leakage (EL, O2•− and activities of superoxide dismutase (SOD, peroxidase (POD, while declined chlorophyll content. No significant differences were found between control and treatments in leaf water content (LWC and catalase (CAT activity. Additionally, 37 metabolic compounds were detected in purslane. Through pathway analysis, 17 metabolites were directly involved in the glycolysis metabolic pathway. The present study indicated that combined drought and heat stress caused more serious damage in purslane than individual stress. To survive, purslane has a high capability to cope with environmental stress conditions through activation of physiological and metabolic pathways.

Physiological and Metabolic Changes of Purslane (Portulaca oleracea L.) in Response to Drought, Heat, and Combined Stresses

Science.gov (United States)

Jin, Rui; Wang, Yanping; Liu, Ruijie; Gou, Junbo; Chan, Zhulong

2016-01-01

Purslane (Portulaca oleracea L.) is a fleshy herbaceous plant. So far, little information is available on the response of this plant to combined drought and heat stress. In this study, changes in physiological and metabolic levels were characterized after treatments with drought, heat and combined stresses. Both individual and combined stress treatments increased malondialdehyde (MDA), electrolyte leakage (EL), O2•− and activities of superoxide dismutase (SOD), peroxidase (POD), while declined chlorophyll content. No significant differences were found between control and treatments in leaf water content (LWC) and catalase (CAT) activity. Additionally, 37 metabolic compounds were detected in purslane. Through pathway analysis, 17 metabolites were directly involved in the glycolysis metabolic pathway. The present study indicated that combined drought and heat stress caused more serious damage in purslane than individual stress. To survive, purslane has a high capability to cope with environmental stress conditions through activation of physiological and metabolic pathways. PMID:26779204

ComfortPower. Design, construction and evaluation of a combined fuel-cell and heat pump system

Energy Technology Data Exchange (ETDEWEB)

Silversand, Fredrik (Catator AB, Lund (Sweden))

2010-12-15

Catator AB has constructed, commissioned and evaluated a combined fuel-cell and heat-pump system (ComfortPower). The basic idea behind the project was to demonstrate the possibility to achieve ultrahigh thermal efficiencies when combining fuel-cell technologies and heat pumps. Moreover, the system should provide a great flexibility with respect to the fuel mix and should in addition to heat provide surplus electricity and cooling. The system was built on a HT-PEM platform (high temperature polymer electrolyte fuel cell from Serenergy a/s), which was operated by Catators proprietary Optiformer technology. The power generator was combined with a heat pump module (F1145-5, 230 V), supplied by Nibe. The system was packaged into a cabinet (1.65 x 0.6 x 0.6 m) comprising the power module, the heat pump, all necessary balance-of-plant components and the control system. The power output from the fuel-cell system was around 1.35 kW, which enabled operation of the heat pump compressor. By utilizing surplus heat energy from the fuel cell it was possible to achieve a favourable operation point in the heat pump system, resulting in a high overall COP (coefficient of performance). The heat output from the system was as high as 10 kW whereas 6 kW cooling could be provided. The thermal efficiencies measured in experiments were normally around 200%, calculated on the lower heating value of the fuel. A number of fuels have been investigated in the fuel cell system, including both gaseous (natural gas/LPG) and liquid fuels (alcohols and kerosene). Indeed, the system has a wide fuel flexibility, which opens up for a variety of applications in campus villages and buildings. This study has demonstrated the possibility to reduce the carbon dioxide footprint by a factor of 2 over conventional boilers in heating applications. In addition the unit can be operated on a variety of fuels and can produce cooling and electricity in addition to heat. A fully working system has been designed

Prospects for city-scale combined heat and power in the UK

Energy Technology Data Exchange (ETDEWEB)

Nelson, John [Finnpower, High Wycombe (United Kingdom); Amos, John [Hoare Lea and Partners, Bristol (United Kingdom); Hutchinson, David [London Research Centre (United Kingdom); Denman, Malcolm [Sheffield Hallam Univ. (United Kingdom). School of Engineering

1996-07-01

City-scale combined heat and power/district heating (CHP/DH) brings to a number of European countries major social and commercial benefits which have been almost totally overlooked in the UK. To bring CHP/DH to the UK, it is necessary first to convince people of the benefits and then to persuade the Government to introduce the necessary legislation to allow the establishment of true city energy utilities on European lines. Neither task will be easy because of the resultant effect on the British fuel industries. The necessary changes must inevitably be gradual and there would, in any case, be a substantial role for the fuel industries - which they must be made aware of. (author)

Thermodynamic performance analysis and optimization of a solar-assisted combined cooling, heating and power system

International Nuclear Information System (INIS)

Wang, Jiangjiang; Lu, Yanchao; Yang, Ying; Mao, Tianzhi

2016-01-01

This study aims to present a thermodynamic performance analysis and to optimize the configurations of a hybrid combined cooling, heating and power (CCHP) system incorporating solar energy and natural gas. A basic natural gas CCHP system containing a power generation unit, a heat recovery system, an absorption cooling system and a storage tank is integrated with solar photovoltaic (PV) panels and/or a heat collector. Based on thermodynamic modeling, the thermodynamic performance, including energy and exergy efficiencies, under variable work conditions, such as electric load factor, solar irradiance and installation ratio, of the solar PV panels and heat collector is investigated and analyzed. The results of the energy supply side analysis indicate that the integration of solar PV into the CCHP system more efficiently improves the exergy efficiency, whereas the integration of a solar heat collector improves the energy efficiency. To match the building loads, the optimization method combined with the operation strategy is employed to optimize the system configurations to maximize the integrated benefits of energy and economic costs. The optimization results of demand–supply matching demonstrate that the integration of a solar heat collector achieves a better integrated performance than the solar PV integration in the specific case study. - Highlights: • Design a CCHP system integrated with solar PV and heat collector. • Present the energy and exergy analyses under variable work conditions. • Propose an optimization method of CCHP system for demand-supply matching.

Industrial Application of Topology Optimization for Combined Conductive and Convective Heat Transfer Problems

DEFF Research Database (Denmark)

Zhou, Mingdong; Alexandersen, Joe; Sigmund, Ole

2016-01-01

This paper presents an industrial application of topology optimization for combined conductive and convective heat transfer problems. The solution is based on a synergy of computer aided design and engineering software tools from Dassault Systemes. The considered physical problem of steady......-state heat transfer under convection is simulated using SIMULIA-Abaqus. A corresponding topology optimization feature is provided by SIMULIA-Tosca. By following a standard workflow of design optimization, the proposed solution is able to accommodate practical design scenarios and results in efficient...

Thermodynamic performance analysis of a combined power cycle using low grade heat source and LNG cold energy

International Nuclear Information System (INIS)

Kim, Kyoung Hoon; Kim, Kyung Chun

2014-01-01

Thermodynamic analysis of a combined cycle using a low grade heat source and LNG cold energy was carried out. The combined cycle consisted of an ammonia–water Rankine cycle with and without regeneration and a LNG Rankine cycle. A parametric study was conducted to examine the effects of the key parameters, such as ammonia mass fraction, turbine inlet pressure, condensation temperature. The effects of the ammonia mass fraction on the temperature distributions of the hot and cold streams in heat exchangers were also investigated. The characteristic diagram of the exergy efficiency and heat transfer capability was proposed to consider the system performance and expenditure of the heat exchangers simultaneously. The simulation showed that the system performance is influenced significantly by the parameters with the ammonia mass fraction having largest effect. The net work output of the ammonia–water cycle may have a peak value or increase monotonically with increasing ammonia mass fraction, which depends on turbine inlet pressure or condensation temperature. The exergy efficiency may decrease or increase or have a peak value with turbine inlet pressure depending on the ammonia mass fraction. - Highlights: • Thermodynamic analysis was performed for a combined cycle utilizing LNG cold energy. • Ammonia–water Rankine cycle and LNG Rankine cycle was combined. • A parametric study was conducted to examine the effects of the key parameters. • Characteristics of the exergy efficiency and heat transfer capability were proposed. • The system performance was influenced significantly by the ammonia mass fraction

Investigating the combined effects of heat and lighting on students reaction time in laboratory condition

Directory of Open Access Journals (Sweden)

Zohre Mohebian

2016-12-01

Full Text Available Introduction: In many workplaces there is exposure to heat and light simultaneously. This study investigated the combined effect of heat and lighting on some cognitive performance, i.e. reaction time. Methodology: the present semi-experimental study was conducted 2015 on 33 healthy students (16 girls and 17 boys with a mean age of 22.1 in the thermal stress chamber. The reaction time parameter by the reaction time measurement device, after exposure to different heat surfaces (dry temperatures 22 °C and 37 °C and lighting surfaces (200, 500 and 1500 lux. Data were analyzed using ANOVA test in SPSS-20. Results: The results showed that the average simple, diagnostic, two-color selective, two-sound selective reaction times and reaction time error increased after combined exposure to heat and lighting and showed a significant difference (P<0.05. The maximum score of reaction time belong to temperature of 37 c° and lighting of 1500 lux, the minimum score of reaction time belong to temperature of 22 °c and lighting of 1500 lux.

The Spectral Shift Control Reactor as an option for much improved uranium utilisation in single-batch SMRs

Energy Technology Data Exchange (ETDEWEB)

Lindley, B.A., E-mail: bal29@cam.ac.uk; Parks, G.T.

2016-12-01

Highlights: • A PWR with mixed D{sub 2}O/H{sub 2}O moderator/coolant is investigated for SMR applications. • Heavy water concentration varied over the cycle to give ‘spectral shift’ operation. • Much wetter lattice than normal is neutronically favourable. • Taller fuel stack is thus needed to ensure acceptable MDNBR. • 35–43% increase in uranium utilisation for single batch reactor is possible. - Abstract: The Spectral Shift Control Reactor (SSCR) uses a mix of D{sub 2}O and H{sub 2}O to moderate and cool the reactor. Initially, a high proportion of D{sub 2}O is used, such that the reactor is substantially under-moderated, with excess neutrons being primarily captured in {sup 238}U, breeding {sup 239}Pu. Towards the end of the cycle (EOC), the coolant is predominantly H{sub 2}O, thermalising the neutron spectrum and increasing reactivity. Recently, small modular reactors (SMRs) have gained significant interest as a means of providing a power source that requires little maintenance and refuelling. This motivates long cycles and reduced batch operation. For a single-batch reactor, there is typically a 33% penalty to uranium utilisation compared to a 3-batch reactor. Lattice calculations demonstrate the potential of the SSCR to greatly improve uranium utilisation in single-batch reactors over a range of enrichments. A relatively ‘wet’ lattice is employed which further improves uranium utilisation. Cases with 5% and 15% fissile loading are considered, for which it is respectively possible to achieve 47% and 39% increases in natural uranium utilisation using the SSCR relative to a ‘reference’ light water reactor. In the latter case, if 25% thorium is mixed into the fuel, the improvement in uranium utilisation increases to a total of 49%. Hence, in both cases, it is possible to in effect eliminate the penalty of using a single fuel batch. The ‘wet’ lattice introduces substantial thermal-hydraulic challenges due to the significantly higher fuel

Sustainable renewable energy seawater desalination using combined-cycle solar and geothermal heat sources

KAUST Repository

Missimer, Thomas M.

2013-01-01

Key goals in the improvement of desalination technology are to reduce overall energy consumption, make the process "greener," and reduce the cost of the delivered water. Adsorption desalination (AD) is a promising new technology that has great potential to reduce the need for conventional power, to use solely renewable energy sources, and to reduce the overall cost of water treatment. This technology can desalt seawater or water of even higher salinity using waste heat, solar heat, or geothermal heat. An AD system can operate effectively at temperatures ranging from 55 to 80 °C with perhaps an optimal temperature of 80 °C. The generally low temperature requirement for the feedwater allows the system to operate quite efficiently using an alternative energy source, such as solar power. Solar power, particularly in warm dry regions, can generate a consistent water temperature of about 90 °C. Although this temperature is more than adequate to run the system, solar energy collection only can occur during daylight hours, thereby necessitating the use of heat storage during nighttime or very cloudy days. With increasing capacity, the need for extensive thermal storage may be problematic and could add substantial cost to the development of an AD system. However, in many parts of the world, there are subsurface geothermal energy sources that have not been extensively used. Combining a low to moderate geothermal energy recovery system to an AD system would provide a solution to the thermal storage issue. However, geothermal energy development from particularly Hot Dry Rock is limited by the magnitude of the heat flow required for the process and the thermal conductivity of the rock material forming the heat reservoir. Combining solar and geothermal energy using an alternating 12-h cycle would reduce the probability of depleting the heat source within the geothermal reservoir and provide the most effective use of renewable energy. © 2013 Desalination Publications.

Combined use of solar heat and cogeneration - a perspective for district heating?; Kombinierter Einsatz von solarer Waerme und Kraft-Waerme-Kopplung - eine Perspektive fuer die Nahwaerme?

Energy Technology Data Exchange (ETDEWEB)

Entress, J. [Deutsches Zentrum fuer Luft- und Raumfahrt (DLR), Stuttgart (Germany). Abt. Systemanalyse und Technikbewertung; Steinborn, F. [Zentrum fuer Sonnenenergie- und Wasserstoff-Forschung Baden-Wuerttemberg (ZSW), Stuttgart (Germany). Fachgebiet Systemanalyse

1998-02-01

With Cogeneration of Heat and Power (CHP), climate-endangering CO{sub 2}-emissions can be reduced singificantly. The heat produced can be delivered at prices comparable to those of conventionally produced heat. With solar district heating, yet higher CO{sub 2}-savings are possible but at higher cost. Promising is a combination of CHP and solar district heating: The heat storage of the solar system can be used to level out heat demand, leading to smooth CHP operation, while heat generated by CHP can be used to substitute for low irradiation during the winter period. However, calculations together with simulation and optimization indicate that combining CHP and solar district heating is not the optimal solution in all cases. (orig.) [Deutsch] Der Einsatz von Blockheizkraftwerken (BHKW) kann zu einer deutlichen Reduzierung der klimagefaehrdenden CO{sub 2}-Emissionen beitragen. Dabei kann die ausgekoppelte Waerme etwa zum gleichen Preis wie konventionell erzeugte Waerme abgegeben werden. Hoehere CO{sub 2}-Einsparungen lassen sich hingegen mit solarer Nahwaerme erzielen, allerdings zu hoeheren Kosten. Eine Kombination dieser beiden Waermetechniken verspricht Vorteile: Einerseits kann der Waermespeicher des Solarsystems auch zum Ausgleich von Lastspitzen beim Betrieb des BHKW`s genutzt werden. Andererseits kann die waehrend der einstrahlungsarmen Wintermonate fehlende solare Waerme durch das BHKW erzeugt werden. Detaillierte Simulations- und Optimierungsrechnungen zeigen jedoch, dass eine Kombination dieser Waermetechniken nicht immer empfehlenswert ist. (orig.)

Optimization of operation for combined heat and power plants - CHP plants - with heat accumulators using a MILP formulation

Energy Technology Data Exchange (ETDEWEB)

Grue, Jeppe; Bach, Inger [Aalborg Univ. (Denmark). Inst. of Energy Technology]. E-mails: jeg@iet.auc.dk; ib@iet.auc.dk

2000-07-01

The power generation system in Denmark is extensively based on small combined heat and power plants (CHP plants), producing both electricity and district heating. This project deals with smaller plants spread throughout the country. Often a heat accumulator is used to enable electricity production, even when the heat demand is low. This system forms a very complex problem, both for sizing, designing and operation of CHP plants. The objective of the work is the development of a tool for optimisation of the operation of CHP plants, and to even considering the design of the plant. The problem is formulated as a MILP-problem. An actual case is being tested, involving CHP producing units to cover the demand. The results from this project show that it is of major importance to consider the operation of the plant in detail already in the design phase. It is of major importance to consider the optimisation of the plant operation, even at the design stage, as it may cause the contribution margin to rise significantly, if the plant is designed on the basis of a de-tailed knowledge of the expected operation. (author)

The role of policy instruments for promoting combined heat and power production with low CO2 emissions in district heating systems

International Nuclear Information System (INIS)

Marbe, A.; Harvey, S.

2005-01-01

Policy instruments clearly influence the choice of production technologies and fuels in large energy systems, including district heating networks. Current Swedish policy instruments aim at promoting the use of biofuel in district heating systems, and at promoting electric power generation from renewable energy sources. However, there is increasing pressure to harmonize energy policy instruments within the EU. In addition, natural gas based combined cycle technology has emerged as the technology of choice in the power generation sector in the EU. This study aims at exploring the role of policy instruments for promoting the use of low CO 2 emissions fuels in high performance combined heat and power systems in the district heating sector. The paper presents the results of a case study for a Swedish district heating network where new large size natural gas combined cycle (NGCC) combined heat and power (CHP) is being built. Given the aim of current Swedish energy policy, it is assumed that it could be of interest in the future to integrate a biofuel gasifier to the CHP plant and co-fire the gasified biofuel in the gas turbine unit, thereby reducing usage of fossil fuel. The goals of the study are to evaluate which policy instruments promote construction of the planned NGCC CHP unit, the technical performance of an integrated biofuelled pressurized gasifier with or without dryer on plant site, and which combination of policy instruments promote integration of a biofuel gasifier to the planned CHP unit. The power plant simulation program GateCycle was used for plant performance evaluation. The results show that current Swedish energy policy instruments favour investing in the NGCC CHP unit. The corresponding cost of electricity (COE) from the NGCC CHP unit is estimated at 253 SEK MWh -1 , which is lower than the reference power price of 284 SEK MWh -1 . Investing in the NGCC CHP unit is also shown to be attractive if a CO 2 trading system is implemented. If the value of

Radon mitigation in schools utilising heating, ventilating and air conditioning systems

International Nuclear Information System (INIS)

Fisher, G.; Ligman, B.; Brennan, T.; Shaughnessy, R.; Turk, B.H.; Snead, B.

1994-01-01

As part of a continuing radon in schools technology development effort, EPA's School Evaluation Team has performed radon mitigation in schools by the method of ventilation/pressurisation control technology. Ventilation rates were increased, at a minimum, to meet the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) standard, Ventilation for Acceptable Indoor Air Quality (ASHRAE 62-1989). This paper presents the results and the preliminary evaluations which led to the team's decision to implement this technology. Factors considered include energy penalties, comfort, indoor air quality (IAQ), building shell tightness, and equipment costs. Cost benefit of heat recovery ventilation was also considered. Earlier results of the SEP team's efforts have indicated a severe ventilation problem within the schools of the United States. Two case studies are presented where HVAC technology was implemented for controlling radon concentrations. One involved the installation of a heat recovery ventilator to depressurise a crawl space and provide ventilation to the classrooms which previously had no mechanical ventilation. The other involved the restoration of a variable air volume system in a two-storey building. The HVAC system's controls were restored and modified to provide a constant building pressure differential to control the entry of radon. Pre-mitigation and post-mitigation indoor air pollutant measurements were taken, including radon, carbon dioxide (CO 2 ), particulates, and bio-aerosols. Long-term monitoring of radon, CO 2 , building pressure differentials, and indoor/outdoor temperature and relative humidity is presented. (author)

Chemical Utilisation of CO

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 2. Chemical Utilisation of CO2: A Challenge for the Sustainable World. Dinesh Jagadeesan Bhaskar Joshi Prashant Parameswaran. General Article Volume 20 Issue 2 February 2015 pp 165-176 ...

Experimental study of natural convection heat transfer from an isothermal combined geometry (downward cone- cylinder)

Energy Technology Data Exchange (ETDEWEB)

Mokhtari, A. [Yazd Univ., Yazd (Iran, Islamic Republic of). Dept. of Mechanical Engineering; Goharkhah, M.; Ashjaee, M. [Tehran Univ., Tehran (Iran, Islamic Republic of). Dept. of Mechanical Engineering

2009-07-01

Laminar free convection heat transfer from an isothermal combined geometry which consists of a downward cone attached to a vertical cylinder was studied. In particular, a Mach-Zehnder interferometer was used to determine the change in local and average heat transfer coefficients on the surface of an isothermal combined geometry for different vertex angles. The effect of the vertex angle on heat transfer was also investigated by keeping the height of the cylinder and slant length of the cone constant for all objects. The experimental data showed that the local heat transfer coefficient on the conical part increased in the vicinity of the cylinder and cone intersection. The distance between the point of minimum heat transfer coefficient on the cone and vertex of the cone decreased as the vertex angle increased. The maximum average Nusselt number for a constant Rayleigh number was obtained for the geometry with the smallest vertex angle. For all objects, the average Nusselt number increased with an increase in the Rayleigh number. An experiment was carried out on a vertical isothermal cylinder of circular cross section in order to validate the experimental approach. An analytical solution was found to be in good agreement with experimental results. 31 refs., 9 figs.

Numerical analyses of the effect of a biphasic thermosyphon vapor channel sizes on the heat transfer intensity when heat removing from a power transformer of combined heat and power station

Directory of Open Access Journals (Sweden)

Nurpeiis Atlant

2017-01-01

Full Text Available Numerical analyses of the effect of a biphasic thermosyphon vapor channel sizes on the heat transfer intensity was conducted when heat removing from an oil tank of a power transformer of combined heat and power station (CHP. The power transformer cooling system by the closed biphasic thermosyphon was proposed. The mathematical modeling of heat transfer and phase transitions of coolant in the thermosyphon was performed. The problem of heat transfer is formulated in dimensionless variables “velocity vorticity vector – current function – temperature” and solved by finite difference method. As a result of numerical simulation it is found that an increase in the vapor channel length from 0.15m to 1m leads to increasing the temperature difference by 3.5 K.

Diffusion of combined heat and power in Dutch greenhouses : A case study

NARCIS (Netherlands)

Dijkema, G.P.J.; Kasmire, J.; Van der Veen, R.A.C.

2012-01-01

This report presents the case study of the rapid diffusion of combined heat and power (CHP) units in the Dutch greenhouse horticulture in the period 2003-2009. The aim of the case study is to find explanations for this particular transition, and to generalize on the nature of technology diffusion

German mires - Utilisation and protection

International Nuclear Information System (INIS)

Roderfeld, H.

1996-01-01

Mires in Germany are mainly used for agriculture. Peat mining is important regionally, but forest utilisation less so. Twenty years ago in the former West Germany, the first steps from peatland utilisation to peatland protection were taken. Bog protection programmes were developed first. Nowadays research directed to fen protection has begun, prompted by the decreasing importance of agriculture in Central Europe and an increasing environmental awareness. The situation regarding mire protection in Germany is presented for each Federal State individually. A rough estimate suggests 45 000 ha of protected bogs and 25 000 ha of protected fens. These areas include natural and semi-natural mires as well as rewetted mires. (30 refs.)

Closing the Gap between Research Evidence and Clinical Practice: Jordanian Nurses' Perceived Barriers to Research Utilisation

Science.gov (United States)

Al Khalaileh, Murad; Al Qadire, Mohammad; Musa, Ahmad S.; Al-Khawaldeh, Omar A.; Al Qudah, Hani; Alhabahbeh, Atalla

2016-01-01

Background: The nursing profession is a combination of theory and practical skill, and nurses are required to generate and develop knowledge through implementing research into clinical practice. Considerable number of barriers could hind implementing research findings into practice. Barriers to research utilisation are not identified in the…

Analysis of a combined heating and cooling system model under different operating strategies

Science.gov (United States)

Dzierzgowski, Mieczysław; Zwierzchowski, Ryszard

2017-11-01

The paper presents an analysis of a combined heating and cooling system model under different operating strategies. Cooling demand for air conditioning purposes has grown steadily in Poland since the early 1990s. The main clients are large office buildings and shopping malls in downtown locations. Increased demand for heat in the summer would mitigate a number of problems regarding District Heating System (DHS) operation at minimum power, affecting the average annual price of heat (in summertime the share of costs related to transport losses is a strong cost factor). In the paper, computer simulations were performed for different supply network water temperature, assuming as input, real changes in the parameters of the DHS (heat demand, flow rates, etc.). On the basis of calculations and taking into account investment costs of the Absorption Refrigeration System (ARS) and the Thermal Energy Storage (TES) system, an optimal capacity of the TES system was proposed to ensure smooth and efficient operation of the District Heating Plant (DHP). Application of ARS with the TES system in the DHS in question increases net profit by 19.4%, reducing the cooling price for consumers by 40%.

Properties of indium tin oxide films deposited using High Target Utilisation Sputtering

International Nuclear Information System (INIS)

Calnan, S.; Upadhyaya, H.M.; Thwaites, M.J.; Tiwari, A.N.

2007-01-01

Indium tin oxide (ITO) films were deposited on soda lime glass and polyimide substrates using an innovative process known as High Target Utilisation Sputtering (HiTUS). The influence of the oxygen flow rate, substrate temperature and sputtering pressure, on the electrical, optical and thermal stability properties of the films was investigated. High substrate temperature, medium oxygen flow rate and moderate pressure gave the best compromise of low resistivity and high transmittance. The lowest resistivity was 1.6 x 10 -4 Ω cm on glass while that on the polyimide was 1.9 x 10 -4 Ω cm. Substrate temperatures above 100 deg. C were required to obtain visible light transmittance exceeding 85% for ITO films on glass. The thermal stability of the films was mainly influenced by the oxygen flow rate and thus the initial degree of oxidation. The film resistivity was either unaffected or reduced after heating in vacuum but generally increased for oxygen deficient films when heated in air. The greatest increase in transmittance of oxygen deficient films occurred for heat treatment in air while that of the highly oxidised films was largely unaffected by heating in both media. This study has demonstrated the potential of HiTUS as a favourable deposition method for high quality ITO suitable for use in thin film solar cells

Two-dimensional hexagonal boron nitride as lateral heat spreader in electrically insulating packaging

International Nuclear Information System (INIS)

Bao, Jie; Huang, Shirong; Zhang, Yong; Lu, Xiuzhen; Yuan, Zhichao; Jeppson, Kjell; Liu, Johan; Edwards, Michael; Fu, Yifeng

2016-01-01

The need for electrically insulating materials with a high in-plane thermal conductivity for lateral heat spreading applications in electronic devices has intensified studies of layered hexagonal boron nitride (h-BN) films. Due to its physicochemical properties, h-BN can be utilised in power dissipating devices such as an electrically insulating heat spreader material for laterally redistributing the heat from hotspots caused by locally excessive heat flux densities. In this study, two types of boron nitride based heat spreader test structures have been assembled and evaluated for heat dissipation. The test structures separately utilised a few-layer h-BN film with and without graphene enhancement drop coated onto the hotspot test structure. The influence of the h-BN heat spreader films on the temperature distribution across the surface of the hotspot test structure was studied at a range of heat flux densities through the hotspot. It was found that the graphene-enhanced h-BN film reduced the hotspot temperature by about 8–10 °C at a 1000 W cm −2 heat flux density, a temperature decrease significantly larger than for h-BN film without graphene enhancement. Finite element simulations of the h-BN film predict that further improvements in heat spreading ability are possible if the thermal contact resistance between the film and test chip are minimised. (paper)

Performance Analysis of a Hybrid District Heating System

DEFF Research Database (Denmark)

Mikulandric, Robert; Krajačić, Goran; Duic, Neven

2015-01-01

Hybridisation of district heating systems can contribute to more efficient heat generation through cogeneration power plants or through the share increase of renewable energy sources in total energy consumption while reducing negative aspects of particular energy source utilisation. In this work......, the performance of a hybrid district energy system for a small town in Croatia has been analysed. Mathematical model for process analysis and optimisation algorithm for optimal system configuration has been developed and described. The main goal of the system optimisation is to reduce heat production costs....... Several energy sources for heat production have been considered in 8 different simulation cases. Simulation results show that the heat production costs could be reduced with introduction of different energy systems into an existing district heating system. Renewable energy based district heating systems...

Long-term optimization case studies for combined heat and power system

Directory of Open Access Journals (Sweden)

Polyzakis Apostolis L.

2009-01-01

Full Text Available In the next years distributed poly-generation systems are expected to play an increasingly important role in the electricity infrastructure and market. The successful spread of small-scale generation either connected to the distribution network or on the customer side of the meter depends on diverse issues, such as the possibilities of technical implementation, resource availability, environmental aspects, and regulation and market conditions. The aim of this approach is to develop an economic and parametric analysis of a distributed generation system based on gas turbines able to satisfy the energy demand of a typical hotel complex. Here, the economic performance of six cases combining different designs and regimes of operation is shown. The software Turbomatch, the gas turbine performance code of Cranfield University, was used to simulate the off-design performance of the engines in different ambient and load conditions. A clear distinction between cases running at full load and following the load could be observed in the results. Full load regime can give a shorter return on the investment then following the load. In spite combined heat and power systems being currently not economically attractive, this scenario may change in future due to environmental regulations and unavailability of low price fuel for large centralized power stations. Combined heat and power has a significant potential although it requires favorable legislative and fair energy market conditions to successfully increase its share in the power generation market.

Cost-benefit analysis for combined heat and power plant

International Nuclear Information System (INIS)

Sazdovski, Ace; Fushtikj, Vangel

2004-01-01

The paper presents a methodology and practical application of Cost-Benefit Analysis for Combined Heat and Power Plant (Cogeneration facility). Methodology include up-to-date and real data for cogeneration plant in accordance with the trends ill development of the CHP technology. As a case study a CHP plant that could be built-up in Republic of Macedonia is analyzed. The main economic parameters for project evaluation, such as NPV and IRR are calculated for a number of possible scenarios. The analyze present the economic outputs that could be used as a decision for CHP project acceptance for investment. (Author)

WORKING PARK-FUEL CELL COMBINED HEAT AND POWER SYSTEM

Energy Technology Data Exchange (ETDEWEB)

Allan Jones

2003-09-01

This report covers the aims and objectives of the project which was to design, install and operate a fuel cell combined heat and power (CHP) system in Woking Park, the first fuel cell CHP system in the United Kingdom. The report also covers the benefits that were expected to accrue from the work in an understanding of the full technology procurement process (including planning, design, installation, operation and maintenance), the economic and environmental performance in comparison with both conventional UK fuel supply and conventional CHP and the commercial viability of fuel cell CHP energy supply in the new deregulated energy markets.

Guide to Combined Heat and Power Systems for Boiler Owners and Operators

Energy Technology Data Exchange (ETDEWEB)

Oland, CB

2004-08-19

Combined heat and power (CHP) or cogeneration is the sequential production of two forms of useful energy from a single fuel source. In most CHP applications, chemical energy in fuel is converted to both mechanical and thermal energy. The mechanical energy is generally used to generate electricity, while the thermal energy or heat is used to produce steam, hot water, or hot air. Depending on the application, CHP is referred to by various names including Building Cooling, Heating, and Power (BCHP); Cooling, Heating, and Power for Buildings (CHPB); Combined Cooling, Heating, and Power (CCHP); Integrated Energy Systems (IES), or Distributed Energy Resources (DER). The principal technical advantage of a CHP system is its ability to extract more useful energy from fuel compared to traditional energy systems such as conventional power plants that only generate electricity and industrial boiler systems that only produce steam or hot water for process applications. By using fuel energy for both power and heat production, CHP systems can be very energy efficient and have the potential to produce electricity below the price charged by the local power provider. Another important incentive for applying cogeneration technology is to reduce or eliminate dependency on the electrical grid. For some industrial processes, the consequences of losing power for even a short period of time are unacceptable. The primary objective of the guide is to present information needed to evaluate the viability of cogeneration for new or existing industrial, commercial, and institutional (ICI) boiler installations and to make informed CHP equipment selection decisions. Information presented is meant to help boiler owners and operators understand the potential benefits derived from implementing a CHP project and recognize opportunities for successful application of cogeneration technology. Topics covered in the guide follow: (1) an overview of cogeneration technology with discussions about benefits

Economic evaluation of biogas and natural gas co-firing in gas turbine combined heat and power systems

International Nuclear Information System (INIS)

Kang, Jun Young; Kang, Do Won; Kim, Tong Seop; Hur, Kwang Beom

2014-01-01

This study investigated the economics of co-firing biogas and natural gas within a small gas turbine combined heat and power (CHP) plant. The thermodynamic performance of the CHP plant was calculated with varying gas mixing ratios, forming the basis for the economic analysis. A cost balance equation was used to calculate the costs of electricity and heat. The methodology was validated, and parametric analyses were used to investigate the influence of gas mixing ratio and heat sales ratio on the costs of electricity and heat. The cost of electricity generation from the CHP plant was compared to that of a central combined cycle power plant, and an economical gas mixing ratio range were suggested for various heat sales ratios. It was revealed that the effect of the heat sales ratio on the cost of electricity becomes greater as the proportion of natural gas is increased. It was also demonstrated that the economic return from the installation of CHP systems is substantially affected by the gas mixing ratio and heat sales ratio. Sensitivity analysis showed that influence of economic factors on the CHP plant is greater when a higher proportion of natural gas is used. - Highlights: • An appropriate method to calculate the costs of electricity (COE) and heat (COH) was established. • Both COE and COH increase with increasing natural gas mixing ratio and decreasing heat sales ratio. • The effect of the heat sales ratio on the COE becomes greater as the mixing ratio increases. • The payback period is considerably dependent on the mixing ratio and heat sales ratio

The effect of the combined treatment of gamma irradiation and heating on the aerobic bacterial load of white and black peppers

International Nuclear Information System (INIS)

Mohd Khan Ayob; Ismail Bahari; Osman Hassan; Verumandy Kaleswaran

1985-01-01

The effect of combined heat-irradiation treatment on the aerobic bacterial load of black and white peppers were evaluated in comparison with that of heat or irradiation treatment only. The irradiation doses applied were 0 (control), 2, 4, 6 and 8 kGy and the heating temperatures were 28 (control), 50, 60, 70 and 80 deg C. Results indicated that gamma radiation of 7 kGy and 5 kGy were capable of reducing bacterial population from 3.6 x 10 6 /g and 2.9 x 10 5 /g to 3 /g black and white peppers, respectively. Heating at drying temperature could only reduce the bacterial contaminants to 1/2 log cycle. Combined treatment of irradiation followed by heating is more effective in reducing the bacterial load, and the combined treatment of heating followed by irradiation showed similar effects as in irradiation treatment alone. (author)

Energy renovation of single-family houses in Denmark utilising long-term financing based on equity

DEFF Research Database (Denmark)

Kragh, Jesper; Rose, Jørgen

2011-01-01

This paper aims to present an economic overview of the opportunities for energy renovation of single-family houses in Denmark financed over the long term. The paper focuses on the economic difference between energy savings and the repayment of investment. Taking out the average remaining 20% equity...... in long-term property mortgage loans and utilising it for extensive energy renovation improves both the economy and the extent of included measures. Approximately 30% of energy consumption in Denmark is used for space heating. The existing 1 million single-family houses account for approximately half...

Enhancing Cloud Resource Utilisation using Statistical Analysis

OpenAIRE

Sijin He; Li Guo; Yike Guo

2014-01-01

Resource provisioning based on virtual machine (VM) has been widely accepted and adopted in cloud computing environments. A key problem resulting from using static scheduling approaches for allocating VMs on different physical machines (PMs) is that resources tend to be not fully utilised. Although some existing cloud reconfiguration algorithms have been developed to address the problem, they normally result in high migration costs and low resource utilisation due to ignoring the multi-dimens...

The Social Acceptance of Carbon Dioxide Utilisation: A Review and Research Agenda

International Nuclear Information System (INIS)

Jones, Christopher R.; Olfe-Kräutlein, Barbara; Naims, Henriette; Armstrong, Katy

2017-01-01

CO 2 utilisation technologies—also called carbon dioxide utilisation (CDU) and carbon capture and utilisation (CCU)—convert CO 2 via physical, chemical, or biological processes into carbon-based products. CO 2 utilisation technologies are viewed as a means of helping to address climate change and broadening the raw material base for commodities that can be sold to generate economic revenue. However, while technical research and development into the feasibility of CO 2 utilisation options are accelerating rapidly; at present, there has been limited research into the social acceptance of the technology and CO 2 -derived products. This review article outlines and explores three key dimensions of social acceptance (i.e., socio-political, market, and community acceptance) pertaining to innovation within CO 2 utilisation. The article highlights the importance of considering issues of social acceptance as an aspect of the research, development, demonstration, and deployment process for CO 2 utilisation and explores how key stakeholders operating on each dimension might affect the innovation pathways, investment, and siting decisions relating to CO 2 utilisation facilities and CO 2 -derived products. Beyond providing a state-of-the-art review of current research into the social acceptance of CO 2 utilisation, this article also outlines an agenda for future research in the field.

Combined cycles for pipeline compressor drives using heat

International Nuclear Information System (INIS)

Malewski, W.F.; Holldorff, G.M.

1979-01-01

Combined cycles for pipeline-booster stations using waste heat from gas turbines exhaust can improve the overall efficiency of such stations remarkably. Several working fluids are suitable. Due to existing criteria for selecting a working medium under mentioned conditions, water, ammonia, propane and butane can be considered as practical working fluids. The investigations have shown that: (1) ammonia is advantageous at low exhaust gas and ambient temperatures, (2) water is most effective at high exhaust gas and ambient temperatures, and (3), additionally, hydrocarbons are suitable in a medium range for exhaust gas and condensing temperatures. Not only thermodynamic but also operational features have to be considered. There is not one optimum working fluid but a best one suitable according to the prevailing site conditions

Environmental flows and life cycle assessment of associated petroleum gas utilization via combined heat and power plants and heat boilers at oil fields

International Nuclear Information System (INIS)

Rajović, Vuk; Kiss, Ferenc; Maravić, Nikola; Bera, Oskar

2016-01-01

Highlights: • Environmental impact of associated petroleum gas flaring is discussed. • A modern trend of introducing cogeneration systems to the oil fields is presented. • Three alternative utilization options evaluated with life cycle assessment method. • Producing electricity and/or heat instead of flaring would reduce impacts. - Abstract: Flaring of associated petroleum gas is a major resource waste and causes considerable emissions of greenhouse gases and air pollutants. New environmental regulations are forcing oil industry to implement innovative and sustainable technologies in order to compete in growing energy market. A modern trend of introducing energy-effective cogeneration systems to the oil fields by replacing flaring and existing heat generation technologies powered by associated petroleum gas is discussed through material flow analysis and environmental impact assessment. The environmental assessment is based on the consequential life cycle assessment method and mainly primary data compiled directly from measurements on Serbian oil-fields or company-supplied information. The obtained results confirm that the utilization of associated petroleum gas via combined heat and power plants and heat boilers can provide a significant reduction in greenhouse gas emissions and resource depletion by displacing marginal production of heat and electricity. At the base case scenario, which assumes a 100% heat realization rate, the global warming potential of the combined heat and power plant and heat boiler scenarios were estimated at −4.94 and −0.54 kg CO_2_e_q Sm"−"3, whereas the cumulative fossil energy requirements of these scenarios were −48.7 and −2.1 MJ Sm"−"3, respectively. This is a significant reduction compared to the global warming potential (2.25 kg CO_2_e_q Sm"−"3) and cumulative fossil energy requirements (35.36 MJ Sm"−"3) of flaring. Nevertheless, sensitivity analyses have shown that life cycle assessment results are sensitive

Experimental study including subjective evaluations of mixing and displacement ventilation combined with radiant floor heating/cooling system

DEFF Research Database (Denmark)

Krajcik, Michal; Tomasi, Roberta; Simone, Angela

2013-01-01

Sixteen subjects evaluated the indoor environment in four experiments with different combinations of ventilation systems and radiant heating/cooling systems. In the first two tests, the simulated residential room was equipped either by a mixing ventilation system supplying warm air for space heat...

Calculations of combined radiation and convection heat transfer in rod bundles under emergency cooling conditions

International Nuclear Information System (INIS)

Sun, K.H.; Gonzalez-Santalo, J.M.; Tien, C.L.

1976-01-01

A model has been developed to calculate the heat transfer coefficients from the fuel rods to the steam-droplet mixture typical of Boiling Water Reactors under Emergency Core Cooling System (ECCS) operation conditions during a postulated loss-of-coolant accident. The model includes the heat transfer by convection to the vapor, the radiation from the surfaces to both the water droplets and the vapor, and the effects of droplet evaporation. The combined convection and radiation heat transfer coefficient can be evaluated with respect to the characteristic droplet size. Calculations of the heat transfer coefficient based on the droplet sizes obtained from the existing literature are consistent with those determined empirically from the Full-Length-Emergency-Cooling-Heat-Transfer (FLECHT) program. The present model can also be used to assess the effects of geometrical distortions (or deviations from nominal dimensions) on the heat transfer to the cooling medium in a rod bundle

GLASS MELTING PHENOMENA, THEIR ORDERING AND MELTING SPACE UTILISATION

Directory of Open Access Journals (Sweden)

Němec L.

2013-12-01

Full Text Available Four aspects of effective glass melting have been defined – namely the fast kinetics of partial melting phenomena, a consideration of the melting phenomena ordering, high utilisation of the melting space, and effective utilisation of the supplied energy. The relations were defined for the specific melting performance and specific energy consumption of the glass melting process which involve the four mentioned aspects of the process and indicate the potentials of effective melting. The quantity “space utilisation” has been treated in more detail as an aspect not considered in practice till this time. The space utilisation was quantitatively defined and its values have been determined for the industrial melting facility by mathematical modelling. The definitions of the specific melting performance and specific energy consumption have been used for assessment of the potential impact of a controlled melt flow and high space utilisation on the melting process efficiency on the industrial scale. The results have shown that even the partial control of the melt flow, leading to the partial increase of the space utilisation, may considerably increase the melting performance, whereas a decrease of the specific energy consumption was determined to be between 10 - 15 %.

Utilisation des "algues-fourrage" en aquaculture

OpenAIRE

Chretiennot-dinet, Marie-josèphe; Robert, Rene; His, Edouard

1986-01-01

Les travaux concernant l'utilisation d'algues unicellulaires pour la nutrtion de larves et de juvéniles de bivalves d'intérêt commercial sont analysés. Sur une cinquantaine d'espèces d'algues testées, un dizaine seulement sont produites en grande quantité dans des écloseries commerciales sous le non "d'algues fourrage". Les principales espèces employées sont décrites et leurs caractéristiques majeures illustrées. Les critères permettant de retenir une espèce pour son utilisation en aquacultur...

A combined thermodynamic cycle based on methanol dissociation for IC (internal combustion) engine exhaust heat recovery

International Nuclear Information System (INIS)

Fu, Jianqin; Liu, Jingping; Xu, Zhengxin; Ren, Chengqin; Deng, Banglin

2013-01-01

In this paper, a novel approach for exhaust heat recovery was proposed to improve IC (internal combustion) engine fuel efficiency and also to achieve the goal for direct usage of methanol as IC engine fuel. An open organic Rankine cycle system using methanol as working medium is coupled to IC engine exhaust pipe for exhaust heat recovery. In the bottom cycle, the working medium first undergoes dissociation and expansion processes, and is then directed back to IC engine as fuel. As the external bottom cycle and the IC engine main cycle are combined together, this scheme forms a combined thermodynamic cycle. Then, this concept was applied to a turbocharged engine, and the corresponding simulation models were built for both of the external bottom cycle and the IC engine main cycle. On this basis, the energy saving potential of this combined cycle was estimated by parametric analyses. Compared to the methanol vapor engine, IC engine in-cylinder efficiency has an increase of 1.4–2.1 percentage points under full load conditions, while the external bottom cycle can increase the fuel efficiency by 3.9–5.2 percentage points at the working pressure of 30 bar. The maximum improvement to the IC engine global fuel efficiency reaches 6.8 percentage points. - Highlights: • A combined thermodynamic cycle using methanol as working medium for IC engine exhaust heat recovery is proposed. • The external bottom cycle of exhaust heat recovery and IC engine working cycle are combined together. • IC engine fuel efficiency could be improved from both in-cylinder working cycle and external bottom cycle. • The maximum improvement to the IC engine global fuel efficiency reaches 6.8 percentage points at full load

Air bottoming cycle, an alternative to combined cycles. Final report

Energy Technology Data Exchange (ETDEWEB)

Kaikko, J. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Energy Technology

2002-02-01

In this work, the idea of Air Bottoming Cycle (ABC) has been studied. The objectives for the work have been to establish an understanding of the concept for power and heat generation as well as to find - if possible - feasible concepts for future use in the Swedish energy system. Combined cycle in power generation is an established technology. In the conventional combined cycle, a gas turbine works as a topping cycle together with the steam (Rankine) bottoming cycle. In the ABC the steam bottoming cycle is replaced with a gas turbine (Brayton) bottoming cycle having air as a working fluid. The two gas turbines are thermally connected over a gas-to-gas heat exchanger. This concept promises savings in weight and cost, as well as operating benefits, compared to the Rankine bottoming technology. The ABC has been modelled using a heat balance program, and a parametric study for the concept optimisation as well as for off-design analysis has been performed. Performance of the ABC has been compared to other, established technologies. A preliminary economic evaluation has been made. As a result of the study, it is clarified that the Rankine bottoming cycle with steam remains superior to the ABC as regards electrical efficiency in the medium and large power scale. For small-scale applications (<10 MW{sub e}) where the thermodynamic advantage of the Rankine cycle is not dominating any longer and its economy is burdened by the heavy investment structure, the ABC becomes the better alternative for energy utilisation. A preliminary economic evaluation shows that (at energy prices autumn 2000) the ABC is at the same level as the comparable small-scale cogeneration installations. Due to high power-to-heat ratio however, higher electricity prices will favour the ABC. One interesting feature of the ABC is that about 50% of the dissipated low-value heat from the cycle is carried by clean (sterile) air at the temperature around 200 deg C. This air can be utilised for space heating or

Combined heat and power generation with a HCPV system at 2000 suns

International Nuclear Information System (INIS)

Paredes, Filippo; Montagnino, Fabio M.; Milone, Sergio; Salinari, Piero; Agnello, Simonpietro; Gelardi, Franco M.; Sciortino, Luisa; Cannas, Marco; Bonsignore, Gaetano; Barbera, Marco; Collura, Alfonso; Lo Cicero, Ugo

2015-01-01

This work shows the development of an innovative solar CHP system for the combined production of heat and power based upon HCPV modules working at the high concentration level of 2000 suns. The solar radiation is concentrated on commercial InGaP/InGaAs/Ge triple-junction solar cells designed for intensive work. The primary optics is a rectangular off-axis parabolic mirror while a secondary optic at the focus of the parabolic mirror is glued in optical contact with the cell. Each module consist of 2 axis tracker (Alt-Alt type) with 20 multijunction cells each one integrated with an active heat sink. The cell is connected to an active heat transfer system that allows to keep the cell at a high level of electrical efficiency (ηel > 30 %), bringing the heat transfer fluid (water and glycol) up to an output temperature of 90°C. Accordingly with the experimental data collected from the first 1 kWe prototype, the total amount of extracted thermal energy is above the 50% of the harvested solar radiation. That, in addition the electrical efficiency of the system contributes to reach an overall CHP efficiency of more than the 80%

Combined heat and power generation with a HCPV system at 2000 suns

Energy Technology Data Exchange (ETDEWEB)

Paredes, Filippo; Montagnino, Fabio M.; Milone, Sergio [IDEA s.r.l., C.da Molara Z.I. III Fase, 90018 Termini Imerese (Italy); Salinari, Piero; Agnello, Simonpietro; Gelardi, Franco M.; Sciortino, Luisa; Cannas, Marco [Dipartimento di Fisica e Chimica, Università di Palermo, Via Archirafi 36, 90123 Palermo (Italy); Bonsignore, Gaetano; Barbera, Marco [Dipartimento di Fisica e Chimica, Università di Palermo, Via Archirafi 36, 90123 Palermo (Italy); INAF, Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo (Italy); Collura, Alfonso; Lo Cicero, Ugo [INAF, Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo (Italy)

2015-09-28

This work shows the development of an innovative solar CHP system for the combined production of heat and power based upon HCPV modules working at the high concentration level of 2000 suns. The solar radiation is concentrated on commercial InGaP/InGaAs/Ge triple-junction solar cells designed for intensive work. The primary optics is a rectangular off-axis parabolic mirror while a secondary optic at the focus of the parabolic mirror is glued in optical contact with the cell. Each module consist of 2 axis tracker (Alt-Alt type) with 20 multijunction cells each one integrated with an active heat sink. The cell is connected to an active heat transfer system that allows to keep the cell at a high level of electrical efficiency (ηel > 30 %), bringing the heat transfer fluid (water and glycol) up to an output temperature of 90°C. Accordingly with the experimental data collected from the first 1 kWe prototype, the total amount of extracted thermal energy is above the 50% of the harvested solar radiation. That, in addition the electrical efficiency of the system contributes to reach an overall CHP efficiency of more than the 80%.

Combined heat and power generation with a HCPV system at 2000 suns

Science.gov (United States)

Paredes, Filippo; Montagnino, Fabio M.; Salinari, Piero; Bonsignore, Gaetano; Milone, Sergio; Agnello, Simonpietro; Barbera, Marco; Gelardi, Franco M.; Sciortino, Luisa; Collura, Alfonso; Lo Cicero, Ugo; Cannas, Marco

2015-09-01

This work shows the development of an innovative solar CHP system for the combined production of heat and power based upon HCPV modules working at the high concentration level of 2000 suns. The solar radiation is concentrated on commercial InGaP/InGaAs/Ge triple-junction solar cells designed for intensive work. The primary optics is a rectangular off-axis parabolic mirror while a secondary optic at the focus of the parabolic mirror is glued in optical contact with the cell. Each module consist of 2 axis tracker (Alt-Alt type) with 20 multijunction cells each one integrated with an active heat sink. The cell is connected to an active heat transfer system that allows to keep the cell at a high level of electrical efficiency (ηel > 30 %), bringing the heat transfer fluid (water and glycol) up to an output temperature of 90°C. Accordingly with the experimental data collected from the first 1 kWe prototype, the total amount of extracted thermal energy is above the 50% of the harvested solar radiation. That, in addition the electrical efficiency of the system contributes to reach an overall CHP efficiency of more than the 80%.

Combined Heat and Power Systems for the Provision of Sustainable Energy from Biomass in Buildings

Directory of Open Access Journals (Sweden)

Ortwein Andreas

2016-01-01

Full Text Available Against the background of greenhouse gases causing climate change, combined heat and power (CHP systems fueled by biomass can efficiently supply energy with high flexibility. Such CHP systems will usually consist of one or more thermo-chemical conversion steps and at least one (the more or less separated electric power generation unit. Depending on the main products of the previous conversion steps (e.g. combustible gases or liquids, but also flue gases with sensible heat, different technologies are available for the final power conversion step. This includes steam cycles with steam turbines or engines and different working fluids (water, organic fluids, but also combustion based systems like gas turbines or gas engines. Further promising technologies include fuel cells with high electric efficiency. When integrating such CHP systems in buildings, there are different strategies, especially concerning electric power generation. While some concepts are focusing on base load production, others are regulated either by thermal or by electric power demand. The paper will give a systematic overview on the combination of thermo-chemical conversion of biomass and combined heat and power production technologies. The mentioned building integration strategies will be discussed, leading to conclusions for further research and development in that field.

Antimicrobial activity of suspensions and nanoemulsions of citral in combination with heat or pulsed electric fields.

Science.gov (United States)

Pagán, E; Berdejo, D; Espina, L; García-Gonzalo, D; Pagán, R

2018-01-01

The application of essential oils in form of nanoemulsions has been proposed as a method to improve their solubility in aqueous solutions, and hence their antimicrobial activity. The objective of this study was to evaluate the antimicrobial activity of citral, applied directly or in combined treatments with heat or pulsed electric fields (PEF), as a function of the inoculation procedure assayed: (i) a simple, vigorous shaking method by vortex agitation (suspension of citral; s-citral) or (ii) the previous preparation of nanoemulsions by the emulsion phase inversion (EPI) method (nanoemulsion of citral; n-citral). n-Citral was more effective in either inhibiting or inactivating Escherichia coli O157:H7 Sakai than s-citral. However, when combined with heat, a greater synergistic effect was observed with s-citral rather than with n-citral, either in lab media (pH 7·0 and 4·0) or apple juice. For instance, while almost 5 log 10 cell cycles were inactivated in apple juice after 15 min at 53°C in the presence of 0·1 μl ml -1 of s-citral, the use of n-citral required 30 min. The use of nanoemulsions did not modify the slight synergism observed when citral and mild PEF were combined (150 μs, 30 kV cm -1 ). The exploration of different delivery systems of antimicrobial compounds such as citral in aqueous food products aids in the establishment of successful combined treatments for food preservation. While at room temperature, citral in form of a nanoemulsion shows a higher antimicrobial activity; its combination with heat would imply a partial loss of the outstanding synergistic lethal effect achieved when added in suspension form. Therefore, the most suitable procedure to magnify the synergism between heat and citral when processing juices would merely require an intense homogenization step prior to the combined treatment. © 2017 The Society for Applied Microbiology.

Promoting investments in combined heat and power production in East-European countries

International Nuclear Information System (INIS)

Van Oostvoom, F.; Van Harmelen, T.

1992-01-01

The study concerns the evaluation of the potential of Combined Heat and Power (CHP) locations, both in industry and district heating with a heat demand of at least 20 GJ/h or ca. 1 MWe capacity. In fact 58 Hungarian locations were analyzed on scope and profitability for investment in CHP, using financial accounting models and criteria such as Internal Rate of Return and Pay-back Period. Due to the already existing favourable infrastructure in East European countries the present expectations in Hungary about the CHP capacity to be developed in the future are very optimistic (1300 up till 2000 MWe in the year 2000). Clearly there exist an overoptimism concerning the possibilities of increasing the energy efficiency in former East-European countries by investment in cogeneration. A more financially and economic attractive way for efficiency improvements is promoting energy saving in these countries and thus avoiding investments in supply technologies. 6 refs

The Social Acceptance of Carbon Dioxide Utilisation: A Review and Research Agenda

Energy Technology Data Exchange (ETDEWEB)

Jones, Christopher R., E-mail: c.r.jones@sheffield.ac.uk [UK Centre for Carbon Dioxide Utilisation (CDUUK), University of Sheffield, Sheffield (United Kingdom); Environment and Behaviour Research Group (EBRG), Department of Psychology, University of Sheffield, Sheffield (United Kingdom); Olfe-Kräutlein, Barbara; Naims, Henriette [Institute for Advanced Sustainability Studies (IASS), Potsdam (Germany); Armstrong, Katy [UK Centre for Carbon Dioxide Utilisation (CDUUK), University of Sheffield, Sheffield (United Kingdom)

2017-06-09

CO{sub 2} utilisation technologies—also called carbon dioxide utilisation (CDU) and carbon capture and utilisation (CCU)—convert CO{sub 2}via physical, chemical, or biological processes into carbon-based products. CO{sub 2} utilisation technologies are viewed as a means of helping to address climate change and broadening the raw material base for commodities that can be sold to generate economic revenue. However, while technical research and development into the feasibility of CO{sub 2} utilisation options are accelerating rapidly; at present, there has been limited research into the social acceptance of the technology and CO{sub 2}-derived products. This review article outlines and explores three key dimensions of social acceptance (i.e., socio-political, market, and community acceptance) pertaining to innovation within CO{sub 2} utilisation. The article highlights the importance of considering issues of social acceptance as an aspect of the research, development, demonstration, and deployment process for CO{sub 2} utilisation and explores how key stakeholders operating on each dimension might affect the innovation pathways, investment, and siting decisions relating to CO{sub 2} utilisation facilities and CO{sub 2}-derived products. Beyond providing a state-of-the-art review of current research into the social acceptance of CO{sub 2} utilisation, this article also outlines an agenda for future research in the field.

Energetical and economical assessment of the waste heat problem

International Nuclear Information System (INIS)

Demicheli, U.; Voort, E. van der; Schneiders, A.; Zegers, P.

1977-01-01

Electrical power plants produce large quantities of low grade heat that remain unused. For ecological reasons this waste heat must be dispersed by means of expensive cooling devices. Waste heat could be used in acquacultural and agricultural complexes this replacing large amounts of primary energy. Energetical and economical aspects are discussed. The state of the art of these and other utilisations is outlined. A different approach to the problem is to reduce the production of waste heat. Various strategies to achieve this challenge are outlined and their actual state and possible future developments are discussed. Finally, the various most promising utilizations are examined from an energetical point of view

Experiments on FW-IBW mode conversion heating combined with LHCD on Tore Supra

International Nuclear Information System (INIS)

Basiuk, V.; Becoulet, A.; Imbeaux, F.; Nguyen, F.; Peysson, Y.; Monakhov, I.; Petrov, Y.; Petrov, Y.

1999-01-01

Recent RF heating and current drive investigations revealed a growing interest in a scheme based on mode conversion (MC) of externally excited fast waves (FW) to ion Bernstein waves (IBW). Suitability of MC scheme for on/off axis electron heating has already been reported on Tore Supra. New results, which were obtained during MC experiments combined with Low Hybrid Current Drive (LHCD) are presented in this paper. Application of new experimental tools and numerical techniques provided better insight into the problem of MC power deposition. an outcome of active search for synergistic LHCD-IBW current drive effects is also reported

Determination of the potential for utilising combined heat and power and of the target reduction of CO{sub 2} emissions, inclusive of cost analysis (increased use of combined heat and power); Ermittlung der Potenziale fuer die Anwendung der Kraft-Waerme-Kopplung und der erzielbaren Minderung der CO{sub 2}-Emissionen einschliesslich Bewertung der Kosten (Verstaerkte Nutzung der Kraft-Waerme-Kopplung)

Energy Technology Data Exchange (ETDEWEB)

Horn, Manfred; Ziesing, Hans-Joachim [Deutsches Inst. fuer Wirtschaftsforschung, Berlin (Germany); Matthes, Felix Christian; Harthan, Ralph [Oeko Institut e.V., Berlin (Germany); Menzler, Gerald [VIK Verband der Industriellen Energie- und Kraftwirtschaft e.V., Essen (Germany)

2007-07-15

The report provides a statistical overview of CHP utilisation up to now in Germany, analyses the general economic and political conditions with a view to evaluating the competitiveness of CHP, discusses the effectiveness of the German CHP Act with respect to its contribution to meeting emissions-related goals, analyses the cost-effectiveness of investments in different types of new CHP installations, addresses mid- and longer term potential as well as impediments to the utilisation of CHP installations, presents model simulations of how CHP is expected to develop in the context of economic conditions subject to various general political conditions and makes recommendations with an eye to additional requirements and opportunities to support CHP, against the background of the findings of the analysis. (orig.)

Options for greenhouse emission reduction by using a module for combined heat and power generation

International Nuclear Information System (INIS)

Stankov, Nikola; Ivanov, Bozhidar

2009-01-01

This report contains example of CO 2 emission reduction assessment when using module for combined heat and power generation that is fueled by natural gas. Environmental benefits are related to the type of fuel that is used and the increased efficiency of the combined production process. Choosing of the CHP unit and the assessment scheme are also presented

Mapping of low temperature heat sources in Denmark

DEFF Research Database (Denmark)

Bühler, Fabian; Holm, Fridolin Müller; Huang, Baijia

2015-01-01

heat. The total accessible waste heat potential is found to be approximately 266 PJ per year with 58 % of it below 100 °C. In the natural heat category, temperatures below 20 °C originate from ambient air, sea water and shallow geothermal energy, and temperatures up to 100 °C are found for solar...... and deep geothermal energy. The theoretical solar thermal potential alone would be above 500 PJ per year. For the development of advanced thermodynamic cycles for the integration of heat sources in the Danish energy system, several areas of interest are determined. In the maritime transport sector a high......Low temperature heat sources are available in many applications, ranging from waste heat from industrial processes and buildings to geothermal and solar heat sources. Technical advancements, such as heat pumps with novel cycle design and multi-component working fluids, make the utilisation of many...

Long distance transmission of low grade heat

International Nuclear Information System (INIS)

Arnott, P.T.W.

1977-01-01

This paper is concerned with low and medium temperature water carried by pipeline as a heat transfer medium for the purpose of utilising the waste heat arising from the nuclear power generation process. Different pipelines, single and double, and alternative pipe materials to steel are presented. Later in the paper the effect of the sending-end temperature on the viability of a water pipeline transmission system is discussed and the consequences of using small quantities of steam in order to boost the water temperature are explained. (M.S.)

Wood chip drying in connection with combined heat and power or solar energy in Finland

Directory of Open Access Journals (Sweden)

Rinne Samuli

2014-01-01

Full Text Available 20% of the Finnish district heating (DH power plant fuels are wood-based and the share is increasing. The wood fuel demand probably exceeds the potential supply in the future. The wood fuel drying with waste heat is one profitable opportunity to gain more wood fuel. If the drying energy can be produced with lower primary energy use than combusting the fuel directly, the drying potentially improves the system efficiency. In this study, the drying feasibility in the connection of a combined heat and power (CHP system, possibly with solar collectors, is calculated. The wood fuel heating can be increased profitably by 6%, using the heat from CHP for drying only when the marginal cost of the heat is low enough, i.e. the electricity price is high enough and there is free capacity after the DH demand. Although the drying is profitable, a larger heat storage can also increase the annual result similarly. The best investment choice depends on the plant properties. Here the optimal system enables 20% DH production cost savings. Solar heat may be profitable, when the solar heat has a 2–3% share of the annual heat demand. However, the dryer or larger storage tank are more profitable investments.

Stochastic analysis of residential micro combined heat and power system

DEFF Research Database (Denmark)

Karami, H.; Sanjari, M. J.; Gooi, H. B.

2017-01-01

In this paper the combined heat and power functionality of a fuel-cell in a residential hybrid energy system, including a battery, is studied. The demand uncertainties are modeled by investigating the stochastic load behavior by applying Monte Carlo simulation. The colonial competitive algorithm...... algorithm. The optimized scheduling of different energy resources is listed in an efficient look-up table for all time intervals. The effects of time of use and the battery efficiency and its size are investigated on the operating cost of the hybrid energy system. The results of this paper are expected...

Utilisation of Antenatal Services at the Provincial Hospital, Mongomo ...

African Journals Online (AJOL)

Utilisation of Antenatal Services at the Provincial Hospital, Mongomo, Guinea Equatoria. AAG Jimoh. Abstract. This prospective study was carried out to evaluate the utilisation of antenatal care at the Provincial Specialist Hospital, Mongomo, Guinea Equatoria, paying close attention to the confounding factors affecting ...

Glass melting and its innovation potentials: The combination of transversal and longitudinal circulations and its influence on space utilisation

Czech Academy of Sciences Publication Activity Database

Polák, M.; Němec, Lubomír

2011-01-01

Roč. 357, 16-17 (2011), s. 3108-3116 ISSN 0022-3093 R&D Projects: GA MPO 2A-1TP1/063 Institutional research plan: CEZ:AV0Z40320502 Keywords : space utilisation * sand dissolution * bubble removal * flow patterns * model furnace Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.537, year: 2011

Combined generation of heat and power in central heating systems. Design rules for fitting in; Warmte/kracht in cv-systemen. Ontwerpregels voor inpassing

Energy Technology Data Exchange (ETDEWEB)

Wammes, J.A. [Emicon, Veenendaal (Netherlands); Tijs, J.C. [Tijs Energy Systems, Wijk bij Duurstede (Netherlands); Rulkens, L.J.W. [FD-Bouwzaken/LNV, Wageningen (Netherlands)

1997-03-01

Carefully thought-out integration, a technical and financial feasibility analysis and telemetry are the key concepts in the successful incorporation of total energy (combined heat and power) units into new or existing heating systems. Based on extensive experience with total energy plants, a number of consultants, engineers and suppliers operating in this broad field, on the initiative of the Central Netherlands Gas Company (Gasbedrijf Centraal Nederland) in Utrecht and the Gasunie energy company in Groningen, both in the Netherlands have published a manual entitled `Design rules for incorporating total energy units into central heating systems`. 2 figs., 3 ills., 5 refs. 3 figs., 4 ills., 1 tab.

Identification of Excess Heat Utilisation Potential using GIS: Analysis of Case Studies for Denmark

DEFF Research Database (Denmark)

Bühler, Fabian; Petrovic, Stefan; Ommen, Torben Schmidt

2017-01-01

feasibility of using this approach is evaluated for four scenarios. Special focus is placed on the challenges for the connection of excess heat sources to heat consumers, as well as tax schemes applicable in Denmark. To account for uncertainties in the model input, Monte Carlo simulations and Morris...

Evaluation of the performance of combined cooling, heating, and power systems with dual power generation units

International Nuclear Information System (INIS)

Knizley, Alta A.; Mago, Pedro J.; Smith, Amanda D.

2014-01-01

The benefits of using a combined cooling, heating, and power system with dual power generation units (D-CCHP) is examined in nine different U.S. locations. One power generation unit (PGU) is operated at base load while the other is operated following the electric load. The waste heat from both PGUs is used for heating and for cooling via an absorption chiller. The D-CCHP configuration is studied for a restaurant benchmark building, and its performance is quantified in terms of operational cost, primary energy consumption (PEC), and carbon dioxide emissions (CDE). Cost spark spread, PEC spark spread, and CDE spark spread are examined as performance indicators for the D-CCHP system. D-CCHP system performance correlates well with spark spreads, with higher spark spreads signifying greater savings through implementation of a D-CCHP system. A new parameter, thermal difference, is introduced to investigate the relative performance of a D-CCHP system compared to a dual PGU combined heat and power system (D-CHP). Thermal difference, together with spark spread, can explain the variation in savings of a D-CCHP system over a D-CHP system for each location. The effect of carbon credits on operational cost savings with respect to the reference case is shown for selected locations. - Highlights: • We investigate benefits from using combined cooling, heating, and power systems. • A dual power generation unit configuration is considered for CCHP and CHP. • Spark spreads for cost, energy, and emissions correlate with potential savings. • Thermal difference parameter helps to explain variations in potential savings. • Carbon credits may increase cost savings where emissions savings are possible

Waste heat of HTR power stations for district heating

International Nuclear Information System (INIS)

Bonnenberg, H.; Schlenker, H.V.

1975-01-01

The market situation, the applied techniques, and the transport, for district heating in combination with HTR plants are considered. Analysis of the heat market indicates a high demand for heat at temperatures between 100 and 150 0 C in household and industry. This market for district heating can be supplied by heat generated in HTR plants using two methods: (1) the combined heat and power generation in steam cycle plants by extracting steam from the turbine, and (2) the use of waste heat of a closed gas turbine cycle. The heat generation costs of (2) are negligible. The cost for transportation of heat over the average distance between existing plant sites and consumer regions (25 km) are between 10 and 20% of the total heat price, considering the high heat output of nuclear power stations. Comparing the price of heat gained by use of waste heat in HTR plants with that of conventional methods, considerable advantages are indicated for the combined heat and power generation in HTR plants. (author)

Influence of dimethyl dicarbonate on the resistance of Escherichia coli to a combined UV-Heat treatment in apple juice

Science.gov (United States)

Gouma, Maria; Gayán, Elisa; Raso, Javier; Condón, Santiago; Álvarez, Ignacio

2015-01-01

Commercial apple juice inoculated with Escherichia coli was treated with UV-C, heat (55°C) and dimethyl dicarbonate – DMDC (25, 50, and 75 mg/L)-, applied separately and in combination, in order to investigate the possibility of synergistic lethal effects. The inactivation levels resulting from each treatment applied individually for a maximum treatment time of 3.58 min were limited, reaching 1.2, 2.9, and 0.06 log10 reductions for UV, heat, and DMDC (75 mg/L), respectively. However, all the investigated combinations resulted in a synergistic lethal effect, reducing the total treatment time and UV dose, with the synergistic lethal effect being higher when larger concentrations of DMDC were added to the apple juice. The addition of 75 mg/L of DMDC prior to the combined UV-C light treatment at 55°C resulted in 5 log10 reductions after only 1.8 min, reducing the treatment time and UV dose of the combined UV-Heat treatment by 44%. PMID:26042117

Multi-objective optimization and exergoeconomic analysis of a combined cooling, heating and power based compressed air energy storage system

International Nuclear Information System (INIS)

Yao, Erren; Wang, Huanran; Wang, Ligang; Xi, Guang; Maréchal, François

2017-01-01

Highlights: • A novel tri-generation based compressed air energy storage system. • Trade-off between efficiency and cost to highlight the best compromise solution. • Components with largest irreversibility and potential improvements highlighted. - Abstract: Compressed air energy storage technologies can improve the supply capacity and stability of the electricity grid, particularly when fluctuating renewable energies are massively connected. While incorporating the combined cooling, heating and power systems into compressed air energy storage could achieve stable operation as well as efficient energy utilization. In this paper, a novel combined cooling, heating and power based compressed air energy storage system is proposed. The system combines a gas engine, supplemental heat exchangers and an ammonia-water absorption refrigeration system. The design trade-off between the thermodynamic and economic objectives, i.e., the overall exergy efficiency and the total specific cost of product, is investigated by an evolutionary multi-objective algorithm for the proposed combined system. It is found that, with an increase in the exergy efficiency, the total product unit cost is less affected in the beginning, while rises substantially afterwards. The best trade-off solution is selected with an overall exergy efficiency of 53.04% and a total product unit cost of 20.54 cent/kWh, respectively. The variation of decision variables with the exergy efficiency indicates that the compressor, turbine and heat exchanger preheating the inlet air of turbine are the key equipment to cost-effectively pursuit a higher exergy efficiency. It is also revealed by an exergoeconomic analysis that, for the best trade-off solution, the investment costs of the compressor and the two heat exchangers recovering compression heat and heating up compressed air for expansion should be reduced (particularly the latter), while the thermodynamic performance of the gas engine need to be improved

Combined Natural Convection and Radiation Heat Transfer of Various Absorbing-Emitting-Scattering Media in a Square Cavity

Directory of Open Access Journals (Sweden)

Xianglong Liu

2014-01-01

Full Text Available A numerical model is developed to simulate combined natural convection and radiation heat transfer of various anisotropic absorbing-emitting-scattering media in a 2D square cavity based on the discrete ordinate (DO method and Boussinesq assumption. The effects of Rayleigh number, optical thickness, scattering ratio, scattering phase function, and aspect ratio of square cavity on the behaviors of heat transfer are studied. The results show that the heat transfer of absorbing-emitting-scattering media is the combined results of radiation and natural convection, which depends on the physical properties and the aspect ratio of the cavity. When the natural convection becomes significant, the convection heat transfer is enhanced, and the distributions of NuR and Nuc along the walls are obviously distorted. As the optical thickness increases, NuR along the hot wall decreases. As the scattering ratio decreases, the NuR along the walls decreases. At the higher aspect ratio, the more intensive thermal radiation and natural convection are formed, which increase the radiation and convection heat fluxes. This paper provides the theoretical research for the optimal thermal design and practical operation of the high temperature industrial equipments.

A combined power cycle utilizing low-temperature waste heat and LNG cold energy

International Nuclear Information System (INIS)

Shi Xiaojun; Che Defu

2009-01-01

This paper has proposed a combined power system, in which low-temperature waste heat can be efficiently recovered and cold energy of liquefied natural gas (LNG) can be fully utilized as well. This system consists of an ammonia-water mixture Rankine cycle and an LNG power generation cycle, and it is modelled by considering mass, energy and species balances for every component and thermodynamic analyses are conducted. The results show that the proposed combined cycle has good performance, with net electrical efficiency and exergy efficiency of 33% and 48%, respectively, for a typical operating condition. The power output is equal to 1.25 MWh per kg of ammonia-water mixture. About 0.2 MW of electrical power for operating sea water pumps can be saved. Parametric analyses are performed for the proposed combined cycle to evaluate the effects of key factors on the performance of the proposed combined cycle through simulation calculations. Results show that a maximum net electrical efficiency can be obtained as the inlet pressure of ammonia turbine increases and the peak value increases as the ammonia mass fraction increases. Exergy efficiency goes up with the increased ammonia turbine inlet pressure. With the ammonia mass fraction increases, the net electrical efficiency increases, whereas exergy efficiency decreases. For increasing LNG turbine inlet pressure or heat source temperature, there is also a peak of net electrical efficiency and exergy efficiency. With the increase of LNG gas turbine outlet pressure, exergy efficiency increases while net electrical efficiency drops

Simulating conditions for combined heat and power in the Swedish district heating sector

International Nuclear Information System (INIS)

Knutsson, David

2005-01-01

The most important issues in the European energy sector today are how to increase competitiveness on the energy markets, reduce both CO2 emissions and dependence on imported fuels. These issues are also important aspects of Swedish energy policy. In Sweden, the district heating (DH) sector has commonly been used to achieve Swedish energy policy goals. However, the ongoing integration and deregulation of the energy markets in Europe now means that the Swedish DH sector can also play an important role in achieving international targets. This thesis investigates the extent to which the Swedish DH sector can contribute to compliance with current energy policy targets, both international and Swedish. The study consisted of simulations of the Swedish DH sector response to various policy instruments in a model that takes the local features of virtually all Swedish DH systems into account. The findings show, for example, that there is great potential for combined heat and power (CHP) generation in the Swedish DH sector. By exporting this CHP electricity to other European countries with less effective and fossil dependent power generation plants, the CO2 emissions from the European energy sector could be substantially reduced. This would also result in increased security of supply and competitiveness in the EU, since fuel use would be more effective. In Sweden, increased CHP generation would also be a way of maintaining an effective national security of supply of power

Sizing Combined Heat and Power Units and Domestic Building Energy Cost Optimisation

Directory of Open Access Journals (Sweden)

Dongmin Yu

2017-06-01

Full Text Available Many combined heat and power (CHP units have been installed in domestic buildings to increase energy efficiency and reduce energy costs. However, inappropriate sizing of a CHP may actually increase energy costs and reduce energy efficiency. Moreover, the high manufacturing cost of batteries makes batteries less affordable. Therefore, this paper will attempt to size the capacity of CHP and optimise daily energy costs for a domestic building with only CHP installed. In this paper, electricity and heat loads are firstly used as sizing criteria in finding the best capacities of different types of CHP with the help of the maximum rectangle (MR method. Subsequently, the genetic algorithm (GA will be used to optimise the daily energy costs of the different cases. Then, heat and electricity loads are jointly considered for sizing different types of CHP and for optimising the daily energy costs through the GA method. The optimisation results show that the GA sizing method gives a higher average daily energy cost saving, which is 13% reduction compared to a building without installing CHP. However, to achieve this, there will be about 3% energy efficiency reduction and 7% input power to rated power ratio reduction compared to using the MR method and heat demand in sizing CHP.

Evaluating the potential of process sites for waste heat recovery

International Nuclear Information System (INIS)

Oluleye, Gbemi; Jobson, Megan; Smith, Robin; Perry, Simon J.

2016-01-01

Highlights: • Analysis considers the temperature and duties of the available waste heat. • Models for organic Rankine cycles, absorption heat pumps and chillers proposed. • Exploitation of waste heat from site processes and utility systems. • Concept of a site energy efficiency introduced. • Case study presented to illustrate application of the proposed methodology. - Abstract: As a result of depleting reserves of fossil fuels, conventional energy sources are becoming less available. In spite of this, energy is still being wasted, especially in the form of heat. The energy efficiency of process sites (defined as useful energy output per unit of energy input) may be increased through waste heat utilisation, thereby resulting in primary energy savings. In this work, waste heat is defined and a methodology developed to identify the potential for waste heat recovery in process sites; considering the temperature and quantity of waste heat sources from the site processes and the site utility system (including fired heaters and, the cogeneration, cooling and refrigeration systems). The concept of the energy efficiency of a site is introduced – the fraction of the energy inputs that is converted into useful energy (heat or power or cooling) to support the methodology. Furthermore, simplified mathematical models of waste heat recovery technologies using heat as primary energy source, including organic Rankine cycles (using both pure and mixed organics as working fluids), absorption chillers and absorption heat pumps are developed to support the methodology. These models are applied to assess the potential for recovery of useful energy from waste heat. The methodology is illustrated for an existing process site using a case study of a petroleum refinery. The energy efficiency of the site increases by 10% as a result of waste heat recovery. If there is an infinite demand for recovered energy (i.e. all the recoverable waste heat sources are exploited), the site

Combined Heat Transfer in High-Porosity High-Temperature Fibrous Insulations: Theory and Experimental Validation

Science.gov (United States)

Daryabeigi, Kamran; Cunnington, George R.; Miller, Steve D.; Knutson, Jeffry R.

2010-01-01

Combined radiation and conduction heat transfer through various high-temperature, high-porosity, unbonded (loose) fibrous insulations was modeled based on first principles. The diffusion approximation was used for modeling the radiation component of heat transfer in the optically thick insulations. The relevant parameters needed for the heat transfer model were derived from experimental data. Semi-empirical formulations were used to model the solid conduction contribution of heat transfer in fibrous insulations with the relevant parameters inferred from thermal conductivity measurements at cryogenic temperatures in a vacuum. The specific extinction coefficient for radiation heat transfer was obtained from high-temperature steady-state thermal measurements with large temperature gradients maintained across the sample thickness in a vacuum. Standard gas conduction modeling was used in the heat transfer formulation. This heat transfer modeling methodology was applied to silica, two types of alumina, and a zirconia-based fibrous insulation, and to a variation of opacified fibrous insulation (OFI). OFI is a class of insulations manufactured by embedding efficient ceramic opacifiers in various unbonded fibrous insulations to significantly attenuate the radiation component of heat transfer. The heat transfer modeling methodology was validated by comparison with more rigorous analytical solutions and with standard thermal conductivity measurements. The validated heat transfer model is applicable to various densities of these high-porosity insulations as long as the fiber properties are the same (index of refraction, size distribution, orientation, and length). Furthermore, the heat transfer data for these insulations can be obtained at any static pressure in any working gas environment without the need to perform tests in various gases at various pressures.

Combined Heat and Power Systems for the Provision of Sustainable Energy from Biomass in Buildings

OpenAIRE

Ortwein Andreas

2016-01-01

Against the background of greenhouse gases causing climate change, combined heat and power (CHP) systems fueled by biomass can efficiently supply energy with high flexibility. Such CHP systems will usually consist of one or more thermo-chemical conversion steps and at least one (the more or less separated) electric power generation unit. Depending on the main products of the previous conversion steps (e.g. combustible gases or liquids, but also flue gases with sensible heat), different techno...

Use of hydrogeothermal energy to support traditional heat supply systems; Nutzung der Energie von geothermalen Gewaessern zur Unterstuetzung der traditionellen Waermeversorgungssysteme

Energy Technology Data Exchange (ETDEWEB)

Kabat, M; Nowak, W; Sobanski, R [Technische Univ., Szczecin (Poland)

1997-12-01

In the Szczecin Region, there are considerable resources of geothermal waters with temperatures from about 30 to 120 C. The authors present in their paper, on the example of selected urban centres, a possibility of utilising geothermal energy for modernisation of traditional heating systems. Among others, the idea of using geothermal energy in combination with conventional heat and power plants has been discussed and the geothermal heating system in Pyrzyce commissioned in February 1996 has been presented. (orig.) [Deutsch] In der Woiwodschaft-Szczecin sind betraechtliche Vorraete der geothermalen Gewaesser mit den Temperaturen von 30 bis ca. 120 C vorhanden. Im vorliegenden Referat stellen die Autoren am Beispiel einiger staedtischer Gebiete die Moeglichkeit, die geothermale Energie zur Modernisierung der traditionellen Waermeversorgungssysteme zu nutzen. Unter anderem wurde das Nutzungskonzept der geothermalen Waermequelle gekopplelt mit konventionellen Heizkraftwerken beschrieben und das im Februar 1996 in Betrieb genommene geothermale Waermeversorgungssysteme in Pyrzyce praesentiert. (orig.)

Solar air heating system for combined DHW and space heating

Energy Technology Data Exchange (ETDEWEB)

Oestergaard Jensen, S.; Bosanac, M.

2002-12-01

The project deals with the development and testing of a simple system for utilization of the summer excess heat from small solar air heating systems for preheating of fresh air. The principle of the system is to lead the heated air down around a domestic hot water tank letting the surface of the tank act as heat exchanger between the air and the water. In order to increase the heat transfer, coefficient fins into the air stream were mounted on the tank. A complete system with 3 m{sup 2} solar air collector, ductworks and a 85 litre storage were set up and extensively monitored. The air stream through the system was created by a fan connected directly to one or two PV-panels leading to a solar radiation dependent flow rate without the use of any other control. Based on monitoring results the system was characterized and a TRNSYS model of the system was developed and calibrated/validated. The monitoring and the simulations with the TRNSYS model revealed several interesting things about the system. The monitoring revealed that the system is capable of bringing the temperature of the water in the storage above 60 deg. C at warm days with clear sky conditions. The storage is very stratified, which is beneficial as usable hot water temperatures rather quickly are obtained. The performance was highly dependent on the airflow rate through the system. It can be concluded that the investigated system will have a performance in the order of 500 kWh during the winter, spring and autumn months and around 250 kWh during the four summer months - or in total a yearly performance of 750 kWh/m{sup 2}. A small traditional solar heating system for preheating of domestic hot water would have a higher performance during the four summer months, but no performance during the rest of the year if the system is installed in a summer house, which only is occupied during the summer. The parametric analysis further indicates that it is possible to further optimise the system when the thermal

Sewage sludge utilisation and disposal alternatives and their comparison; Puhdistamolietteiden hyoedyntaemis- ja loppusijoitusvaihtoehdot sekae niiden vertailu

Energy Technology Data Exchange (ETDEWEB)

Paatero, P.

2001-07-01

Sludge production will presumably not decrease in future. At present agricultural use of sludge is unstable and landfilling will most probably be restricted in the following years. The objective of this thesis is to gather information on options for sludge treatment and utilisation and to compare these options in order to find the best possible solution for future alternatives of sludge utilisation. Finnish and international literature as well as Finnish and EU legislation have been reviewed. Furthermore the mentoring group of this thesis as well as other experts in Finland have been used as a source of information. Sludge contains not only plant nutrients and organic matter but also varying quantities of a number of more or less hazardous substances. The quality and quantity of sewage sludge are described and possible health and environmental risks caused by sewage sludge are pointed out. The legislation linked to sludge utilisation and its demands are also presented. The sludge processing methods reviewed are: thickening, lime stabilisation, aerobic digestion, anaerobic digestion, composting and mechanical and thermal drying. In addition, the positive and negative sides of the stabilisation processes are looked at in greater detail. Agricultural use, landscaping, forestry, landfill, incineration, sludge derived products and newer processing technologies are reviewed as sludge utilisation options. Their environmental impacts, positive and negative sides and practical feasibility are evaluated. Various treatment utilisation combinations are also compared. Furthermore a rough cost assessment is presented. The optimal utilisation alternative has to be chosen case by case. The best use of plant nutrients and valuable organic matter is obtained in agricultural use or in landscaping. In the present situation it is difficult to enhance the portion of agricultural use, and landscaping is restricted by a low demand on the market. Incineration is an expensive option and can

An effective heuristic for combined heat-and-power production planning with power ramp constraints

International Nuclear Information System (INIS)

Rong, Aiying; Lahdelma, Risto

2007-01-01

Combined heat-and-power (CHP) production is an increasingly important technology for its efficient utilization of primary-energy resources and for reducing CO 2 emissions. In the CHP plant, the generation of heat-and-power follows a joint characteristic, which makes the determination of both the marginal power production cost (MPPC) and the feasible operating region for the plant more complicated than for the power-only generation plant. Due to the interdependence between heat and power production, the power-ramp constraints, which limit how much the power production of a CHP plant may increase or decrease between two successive periods, may also imply constraints on the heat production. In this paper, we investigate the impact of power-ramp constraints on CHP production planning and develop a robust heuristic for dealing with the power-ramp constraints based on the solution to the problem with relaxed ramp-constraints (RRC). Numerical results based on realistic production models show that the heuristic can generate high-quality solutions efficiently. (author)

Heating up the gas cooling market

International Nuclear Information System (INIS)

Watt, G.

2001-01-01

Gas cooling is an exciting technology with a potentially bright future. It comprises the production of cooling (and heating) in buildings and industry, by substituting environmentally-friendlier natural gas or LPG over predominantly coal-fired electricity in air conditioning equipment. There are currently four established technologies using gas to provide cooling energy or conditioned air. These are: absorption, both direct gas-fired and utilising hot water or steam; gas engine driven vapour compression (GED); cogeneration, with absorption cooling driven by recovered heat; and desiccant systems. The emergence of gas cooling technologies has been, and remains, one of evolution rather than revolution. However, further development of the technology has had a revolutionary effect on the performance, reliability and consumer acceptability of gas cooling products. Developments from world-renowned manufacturers such as York, Hitachi, Robur and Thermax have produced a range of absorption equipment variously offering: the use of 100 percent environmentally-friendly refrigerants, with zero global warming potential; the ideal utilisation of waste heat from cogeneration systems; a reduction in electrical distribution and stand-by generation capacity; long product life expectancy; far less noise and vibration; performance efficiency maintained down to about 20 percent of load capacity; and highly automated and low-cost maintenance. It is expected that hybrid systems, that is a mixture of gas and electric cooling technologies, will dominate the future market, reflecting the uncertainty in the electricity market and the prospects of stable future gas prices

Inactivation of Nondesiccated and Desiccated Cronobacter sakazakii in Reconstituted Infant Formula by Combination of Citral and Mild Heat.

Science.gov (United States)

Shi, Chao; Jia, Zhenyu; Sun, Yi; Chen, Yifei; Guo, Du; Liu, Zhiyuan; Wen, Qiwu; Guo, Xiao; Ma, Linlin; Yang, Baowei; Baloch, Allah Bux; Xia, Xiaodong

2017-07-01

The objective of this study was to evaluate the combined effect of citral plus mild heat on nondesiccated and desiccated Cronobacter sakazakii in reconstituted infant formula. Various concentrations of citral (0, 0.3, 0.6, and 0.9%) combined with various temperatures (25, 45, 50, and 55°C) were applied to nondesiccated and desiccated cocktails of three C. sakazakii strains (approximately 6.0 log CFU mL -1 ) in reconstituted infant formula, and the bacterial populations were assayed periodically. The combined treatments had marked antimicrobial effects on C. sakazakii compared with the control. Desiccated cells were more susceptible to citral than were nondesiccated cells in reconstituted infant formula. These findings suggest there is a potential application of citral in combination with mild heat to control C. sakazakii during preparation of reconstituted infant formula.

Heat Pumps in CHP Systems

DEFF Research Database (Denmark)

Ommen, Torben Schmidt

that three configurations are particular advantageous, whereas the two remaining configurations result in system performance close to or below what may be expected from an electric heater. One of the three advantageous configurations is required to be positioned at the location of the heat demand, whereas...... the two remaining can be located at positions with availability of high temperature sources by utilising the DH network to distribute the heat. A large amount of operational and economic constraints limit the applicability of HPs operated with natural working fluids, which may be the only feasible choice...... representation allows infeasible production. Using MIP or NLP optimisation, the number of operation hours and the total production of heat from HPs are significantly increased, as the HPs may be used to shave the load patterns of CHP units in significantly constrained energy systems. A MIP energy system model...

Exergy analysis of a combined heat and power plant with integrated lignocellulosic ethanol production

International Nuclear Information System (INIS)

Lythcke-Jørgensen, Christoffer; Haglind, Fredrik; Clausen, Lasse R.

2014-01-01

Highlights: • We model a system where lignocellulosic ethanol production is integrated with a combined heat and power (CHP) plant. • We conduct an exergy analysis for the ethanol production in six different system operation points. • Integrated operation, district heating (DH) production and low CHP loads all increase the exergy efficiency. • Separate operation has the largest negative impact on the exergy efficiency. • Operation is found to have a significant impact on the exergy efficiency of the ethanol production. - Abstract: Lignocellulosic ethanol production is often assumed integrated in polygeneration systems because of its energy intensive nature. The objective of this study is to investigate potential irreversibilities from such integration, and what impact it has on the efficiency of the integrated ethanol production. An exergy analysis is carried out for a modelled polygeneration system in which lignocellulosic ethanol production based on hydrothermal pretreatment is integrated in an existing combined heat and power (CHP) plant. The ethanol facility is driven by steam extracted from the CHP unit when feasible, and a gas boiler is used as back-up when integration is not possible. The system was evaluated according to six operation points that alternate on the following three different operation parameters: Load in the CHP unit, integrated versus separate operation, and inclusion of district heating production in the ethanol facility. The calculated standard exergy efficiency of the ethanol facility varied from 0.564 to 0.855, of which the highest was obtained for integrated operation at reduced CHP load and full district heating production in the ethanol facility, and the lowest for separate operation with zero district heating production in the ethanol facility. The results suggest that the efficiency of integrating lignocellulosic ethanol production in CHP plants is highly dependent on operation, and it is therefore suggested that the

EFFECT OF VIBRATION AND HEAT COMBINATION ON PRIMARY DYSMENORRHEA

Directory of Open Access Journals (Sweden)

M. Hoseini

2015-03-01

Full Text Available Background: Primary dysmenorrhoea is a common, idiopathic, chronic pelvic pain syndrome, with unknown aetiology which ‎about 50% of women with regular menstrual period suffer. This study was designed to determine the effect of vibration and heat on primary dysmenorrhea. Materials and Methods: In this clinical trial, 75 female students aged 18-22 years old were evaluated for two menstrual cycles. At the first cycle the participants received the routine pain-relief method (synthetic or herbal medicine and traditional remedies. At the second cycle for each participant combined vibration-heat device was applied for ten minutes during ‎menstrual pain. The average of perceived leg pain, lumbar pain and abdominal pain scores at two cycles were determined. The data were analyzed based on Wilcoxon and T tests by using SPSS (v 16.0 for Windows. Results: The average of all perceived pain scores at two cycles were significantly different before pain relief and after both routine methods and using the device (p<0.001. Those were more significantly reduced after using the device in comparison of using routine methods (p<0.001. Conclusion: Since “vibration-heat” is an effective pain relief method, it can be used as a complementary alternative medicine in primary dysmenorrhea reduction.

Performance and costs of a roof-sized PV/thermal array combined with a ground coupled heat pump

NARCIS (Netherlands)

Bakker, M.; Zondag, H.A.

2005-01-01

A photovoltaic/thermal (PVT) panel is a combination of photovoltaic cells with a solar thermal collector, generating solar electricity and solar heat simultaneously. Hence, PVT panels are an alternative for a combination of separate PV panels and solar thermal collectors. A promising system concept,

Globalisation and Labour Utilisation in Nigeria: Evidence from the ...

African Journals Online (AJOL)

This study examines the influence of globalisation on labour utilisation in Nigeria using the construction industry as a case study. It reveals that the era of globalisation has given rise to profound changes in the way labour is utilised, specifically in terms of employment patterns as well as the related issues of earnings, job ...

Optimal design and operating strategies for a biomass-fueled combined heat and power system with energy storage

DEFF Research Database (Denmark)

Zheng, Yingying; Jenkins, Bryan M.; Kornbluth, Kurt

2018-01-01

An economic linear programming model with a sliding time window was developed to assess designing and scheduling a biomass-fueled combined heat and power system consisting of biomass gasifier, internal combustion engine, heat recovery set, heat-only boiler, producer gas storage and thermal energy......, utility tariff structure and technical and finical performance of the system components. Engine partial load performance was taken into consideration. Sensitivity analyses demonstrate how the optimal BCHP configuration changes with varying demands and utility tariff rates....

Modulation of Antioxidant Defense System Is Associated with Combined Drought and Heat Stress Tolerance in Citrus.

Science.gov (United States)

Zandalinas, Sara I; Balfagón, Damián; Arbona, Vicent; Gómez-Cadenas, Aurelio

2017-01-01

Drought and high temperatures are two major abiotic stress factors that often occur simultaneously in nature, affecting negatively crop performance and yield. Moreover, these environmental challenges induce oxidative stress in plants through the production of reactive oxygen species (ROS). Carrizo citrange and Cleopatra mandarin are two citrus genotypes with contrasting ability to cope with the combination of drought and heat stress. In this work, a direct relationship between an increased antioxidant activity and stress tolerance is reported. According to our results, the ability of Carrizo plants to efficiently coordinate superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), and glutathione reductase (GR) activities involved in ROS detoxification along with the maintenance of a favorable GSH/GSSG ratio could be related to their relative tolerance to this stress combination. On the other hand, the increment of SOD activity and the inefficient GR activation along with the lack of CAT and APX activities in Cleopatra plants in response to the combination of drought and heat stress, could contribute to an increased oxidative stress and the higher sensibility of this citrus genotype to this stress combination.

Model for optimization of plant investments in combined power and heat production systems

Energy Technology Data Exchange (ETDEWEB)

Jantunen, E.; Sinisalo, A.; Koskelainen, L.

1980-01-01

A mathematical model is developed for optimal dimensioning and timing the investments of power and heat production system in a community. The required electric power may be purchased by different production systems, such as: thermal power plants, gas turbines, diesel plants, etc. or by delivering all or part of it from a national power company. Also the required heat may be produced in many different ways in single-purpose or combined plants. The model assumes the extent of the heating system fixed, and it is not optimized. It is assumed that the same company is responsible for supplying both the power and heat for the community. It's aim is to allocate the existing capital in an optimal way, and the model may be used for facilitating the decision in such questions as: what kind of production capacity should be purchased in future; how high should the heat and power capacities be; and when should this additional capacity be available. The report also reviews the methods for forecasting the demand of power and heat and their fluctuation during the planning period. The solution of this large-scale non-linear optimization problem is searched via successive linearizations by using the Method of Approximate Programming (MAP). It was found that the solution method is very suitable for this kind of multivariable problems. The computing times with the Functional Mathematical Programmin System (FMPS) in Univac 1108 computer were quite reasonable.

Simulation study of energetic ion distribution during combined NBI and ICRF heating in LHD

International Nuclear Information System (INIS)

Murakami, S.; Fukuyama, A.; Kasilov, V.

2006-01-01

In the LHD, significant performances of ICRF heating (fundamental, minority heating regime) have been demonstrated and up to 500keV of energetic tail ions have been observed by fast neutral particle analysis (NPA). These measured results indicate a good property of energetic ion confinement in helical systems. From the 9th campaign of LHD experiment (FY2005) a new perpendicular NBI heating system (P<3MW) has been installed and an effective heating of perpendicularly injected beam ions by the higher harmonics ICRF heating is expected. ICRF heating generates highly energetic tail ions, which drift around the torus for a long time (typically on a collisional time scale). Thus, the behavior of these energetic ions is strongly affected by the characteristics of the drift motions, which depend on the magnetic field configuration. In particular, in a three-dimensional (3D) magnetic configuration, complicated drift motions of trapped particles would play an important role in the confinement of the energetic ions and the ICRF heating process. Therefore a global simulation of ICRF heating is necessary for the accurate modeling of the plasma heating process in a 3D magnetic configuration. In this paper we study the energetic ion distribution during combined NBI and 2nd harmonics ICRF heating in LHD using two global simulation codes: a full wave field solver TASK/WK and a drift kinetic equation solver GNET. GNET solves a linearized drift kinetic equation for energetic ions including complicated behavior of trapped particles in 5-D phase space. TASK/WM solves Maxwell's equation for RF wave electric field with complex frequency as a boundary value problem in the 3D magnetic configuration. (author)

Modelling of combined ICRF and NBI heating in JET hybrid plasmas

Directory of Open Access Journals (Sweden)

Gallart Dani

2017-01-01

Full Text Available During the 2015-2016 JET campaigns many efforts have been devoted to the exploration of high performance plasma scenarios envisaged for ITER operation. In this paper we model the combined ICRF+NBI heating in selected key hybrid discharges using PION. The antenna frequency was tuned to match the cyclotron frequency of minority hydrogen (H at the center of the tokamak coinciding with the second harmonic cyclotron resonance of deuterium. The modelling takes into account the synergy between ICRF and NBI heating through the second harmonic cyclotron resonance of deuterium beam ions which allows us to assess its impact on the neutron rate RNT. We evaluate the influence of H concentration which was varied in different discharges in order to test their role in the heating performance. According to our modelling, the ICRF enhancement of RNT increases by decreasing the H concentration which increases the ICRF power absorbed by deuterons. We find that in the recent hybrid discharges this ICRF enhancement was in the range of 10-25%. Finally, we extrapolate the results to D-T and find that the best performing hybrid discharges correspond to an equivalent fusion power of ∼7.0 MW in D-T.

Limiting biomass consumption for heating in 100% renewable energy systems

DEFF Research Database (Denmark)

Mathiesen, Brian Vad; Lund, Henrik; Connolly, David

2012-01-01

-scale solar thermal, large heat pumps, geothermal heat, industrial surplus heat, and waste incineration. Where the energy density in the building stock is not high enough for DH to be economical, geothermal heat pumps can be recommended for individual heating systems, even though biomass consumption is higher......The utilisation of biomass poses large challenges in renewable energy systems while buildings account for a substantial part of the energy supply even in 100% renewable energy systems. In this paper the focus is on how the heating sector can reduce its consumption of biomass, thus leaving biomass...... for other sectors, but while still enabling a 100% renewable energy system. The analyses of heating technologies shows that district heating (DH) systems are important in limiting the dependence on biomass and create cost effective solutions. DH systems are especially important in renewable energy systems...

Measurement of heat treatment induced residual stresses by using ESPI combined with hole-drilling method

Directory of Open Access Journals (Sweden)

Jie Cheng

2010-08-01

Full Text Available In this study, residual stresses in heat treated specimen were measured by using ESPI (Electronic Speckle-Pattern Interferometry combined with the hole-drilling method. The specimen, made of SUS 304 austenitic stainless steel, was quenched and water cooled to room temperature. Numerical simulation using a hybrid FDM/FEM package was also carried out to simulate the heat treatment process. As a result, the thermal stress fields were obtained from both the experiment and the numerical simulation. By comparision of stress fields, results from the experimental method and numerical simulation well agreed to each other, therefore, it is proved that the presented experimental method is applicable and reliable for heat treatment induced residual stress measurement.

Outpatient echocardiography in the evaluation of innocent murmurs in children: utilisation benchmarking.

Science.gov (United States)

Frias, Patricio A; Oster, Matthew; Daley, Patricia A; Boris, Jeffrey R

2016-03-01

We sought to benchmark the utilisation of echocardiography in the outpatient evaluation of heart murmurs by evaluating two large paediatric cardiology centres. Although criteria exist for appropriate use of echocardiography, there are no benchmarking data demonstrating its utilisation. We performed a retrospective cohort study of outpatients aged between 0 and 18 years at the Sibley Heart Center Cardiology and the Children's Hospital of Philadelphia Division of Cardiology, given a sole diagnosis of "innocent murmur" from 1 July, 2007 to 31 October, 2010. Using internal claims data, we compared the utilisation of echocardiography according to centre, patient age, and physician years of service. Of 23,114 eligible patients (Sibley Heart Center Cardiology: 12,815, Children's Hospital of Philadelphia Division of Cardiology: 10,299), 43.1% (Sibley Heart Center Cardiology: 45.2%, Children's Hospital of Philadelphia Division of Cardiology: 40.4%; p1-5 years had the lowest utilisation (32.7%). In two large paediatric cardiology practices, the overall utilisation of echocardiography by physicians with a sole diagnosis of innocent murmur was similar. There was significant and similar variability in utilisation by provider at both centres. Although these data serve as initial benchmarking, the variability in utilisation highlights the importance of appropriate use criteria.

High efficiency combined heat and power facilities - benefits and barriers

International Nuclear Information System (INIS)

Klein, M.

2001-01-01

There are important linkages between the economy, energy production, the environment and our health. Where thermal energy is needed, distributed Combined Heat and Power facilities, using gas turbines, reciprocating engines and future fuel cells can provide significant improvements to our long term mix of energy production. Local generation can also have benefits in security of energy supply and economic savings. This paper is intended to discuss the relevant air pollution and greenhouse gas emissions from modem CHP plants, the emission prevention and reduction methods available, and their operating experience and cost-effectiveness. Mention is made of recently constructed industrial and commercial plants, and institutional barriers to further development. Solutions described for these barriers include the need for more awareness of opportunities, improved access to the electricity grid, the proper design balance between thermal and electric for CHP systems rather than large combined cycles, improved corporate taxation incentives, and the assessment of all environmental and economic benefits when considering such cleaner sources in a restructured energy market. (author)

Thermodynamic effects when utilizing waste heat from condensation in cases of a reduced vacuum in steam turbine plants of thermal power stations, to provide heat at low temperatures

Energy Technology Data Exchange (ETDEWEB)

Vasiljevic, N.; Savic, B.; Stojakovic, M.

1986-01-01

There is an interesting variant of cogeneration in the steam turbine system of a thermal power plant, i.e. the utilisation of the waste heat of condensation with a reduced vacuum without reconstruction of the thermal power plant. The thermodynamic effect in cogeneration was calculated in consideration of the dynamics of heat consumption. This cogeneration process has the advantage of saving primary energy without reconstruction of the thermal power plant.

Preliminary study concerning the influence of combined heat and radiation treatment on the quality of some horticultural products

International Nuclear Information System (INIS)

Langerak, D.Is.; Bruurs, M.F.J.

1973-01-01

In collaboration with a canning factory a number of horticultural products were preserved by means of the combined irradiation and heating treatment. The aim was to study the influence of the parameters irradiation and heat on quality and microbiological spoilage. The products were exposed to gamma-rays with doses varying from 0 to 1 Mrad. The heat treatment varied from 5 to 40 minutes at 98 to 121 0 C; time and temperature depended on the type of product. The sterilization value (F value) was measured by means of the method of Esty and Meyer for products with pH>5. The canned products were stored afterwards at 20-55 0 C. The organoleptic test showed that the colour and texture of most products were improved by the combined treatment, provided the irradiation dose did not exceed 0.25 Mrad. Strawberries in syrup discoloured at 0.1 Mrad. For a number of products the improved colour was partially lost during storage. Flavour and taste were not generally influenced unfavourably at doses up to 0.3 Mrad (exception: strawberries). The treatment sequence did not affect distinctly the quality or microbiological spoilage. The sterilization time (F value) of the combined treatment was determined by the shortest heating period required for the tenderness of the product. (F.J.)

Combined heat and gamma-irradiation treatments for the control of strawberry diseases under market conditions

International Nuclear Information System (INIS)

Brodrick, H.T.; Thomas, A.C.; Van Tonder, A.J.; Terblanche, J.C.

1977-02-01

The spoilage of strawberries under local market conditions was investigated. It was confirmed that the major losses are due to 'leak' disease caused by Rhizopus stolonifer (Ehr. ex Fr.) Lind. It was also established that further fruit losses in summer are due to anthracnose caused by the fungus Colletotrichum acutatum Simmonds. This is the first time that the latter pathogen has been isolated and identified and recognised as a problem on strawberries in South Africa. Studies with R. stolonifer in culture showed that 46 degrees Celsius for 20 min (the previous international standard heat treatment for fruit) was disappointing, while a treatment at 50 degrees Celsius for 10 min effectively inhibited spore germination. Irradiation studies with cultures of R. stolonifer and C. acutatum showed that a dose of 200 and 100 krad, respectively, resulted in excellent inhibition of spore germination. However, irradiating in nitrogen gas resulted in a tenfold reduction in the effectiveness of the irradiation treatments. The use of nitrogen during irradiation, therefore, cannot be considered, especially where an effective control of the fungal pathogens is desired. Investigations with different cultivars clearly demonstrated the synergistic effect on disease control obtained when combining heat and irradiation treatments. The combination treatment (moist heat at 50-52 degrees Celsius for 10 min plus 200 krad), besides effectively controlling both diseases in strawberries, did not adversely affect berry quality. In simulated transport tests it was shown that a minimal amount of berry softening did occur with this treatment, but this adverse effect was negligible compared with the beneficial effect obtained from disease control. In semi-commercial experiments it was shown that the combination heat and irradiation treatment effectively controlled spoilage diseases for a period of several days from picking, thus allowing sufficient time to market the fruit under local market

Optimal placement of combined heat and power scheme (cogeneration): application to an ethylbenzene plant

International Nuclear Information System (INIS)

Zainuddin Abd Manan; Lim Fang Yee

2001-01-01

Combined heat and power (CHP) scheme, also known as cogeneration is widely accepted as a highly efficient energy saving measure, particularly in medium to large scale chemical process plants. To date, CHP application is well established in the developed countries. The advantage of a CHP scheme for a chemical plant is two-fold: (i) drastically cut down on the electricity bill from on-site power generation (ii) to save the fuel bills through recovery of the quality waste heat from power generation for process heating. In order to be effective, a CHP scheme must be placed at the right temperature level in the context of the overall process. Failure to do so might render a CHP venture worthless. This paper discusses the procedure for an effective implementation of a CHP scheme. An ethylbenzene process is used as a case study. A key visualization tool known as the grand composite curves is used to provide an overall picture of the process heat source and heat sink profiles. The grand composite curve, which is generated based on the first principles of Pinch Analysis enables the CHP scheme to be optimally placed within the overall process scenario. (Author)

How to identify, assess and utilise mobile medical applications in clinical practice.

Science.gov (United States)

Aungst, T D; Clauson, K A; Misra, S; Lewis, T L; Husain, I

2014-02-01

There are thousands of medical applications for mobile devices targeting use by healthcare professionals. However, several factors related to the structure of the existing market for medical applications create significant barriers preventing practitioners from effectively identifying mobile medical applications for individual professional use. To define existing market factors relevant to selection of medical applications and describe a framework to empower clinicians to identify, assess and utilise mobile medical applications in their own practice. Resources available on the Internet regarding mobile medical applications, guidelines and published research on mobile medical applications. Mobile application stores (e.g. iTunes, Google Play) are not effective means of identifying mobile medical applications. Users of mobile devices that desire to implement mobile medical applications into practice need to carefully assess individual applications prior to utilisation. Searching and identifying mobile medical applications requires clinicians to utilise multiple references to determine what application is best for their individual practice methods. This can be done with a cursory exploration of mobile application stores and then moving onto other available resources published in the literature or through Internet resources (e.g. blogs, medical websites, social media). Clinicians must also take steps to ensure that an identified mobile application can be integrated into practice after carefully reviewing it themselves. Clinicians seeking to identify mobile medical application for use in their individual practice should use a combination of app stores, published literature, web-based resources, and personal review to ensure safe and appropriate use. © 2014 John Wiley & Sons Ltd.

Utilising green and bluespace to mitigate urban heat island intensity.

Science.gov (United States)

Gunawardena, K R; Wells, M J; Kershaw, T

2017-04-15

It has long been recognised that cities exhibit their own microclimate and are typically warmer than the surrounding rural areas. This 'mesoscale' influence is known as the urban heat island (UHI) effect and results largely from modification of surface properties leading to greater absorption of solar radiation, reduced convective cooling and lower water evaporation rates. Cities typically contain less vegetation and bodies of water than rural areas, and existing green and bluespace is often under threat from increasing population densities. This paper presents a meta-analysis of the key ways in which green and bluespace affect both urban canopy- and boundary-layer temperatures, examined from the perspectives of city-planning, urban climatology and climate science. The analysis suggests that the evapotranspiration-based cooling influence of both green and bluespace is primarily relevant for urban canopy-layer conditions, and that tree-dominated greenspace offers the greatest heat stress relief when it is most needed. However, the magnitude and transport of cooling experienced depends on size, spread, and geometry of greenspaces, with some solitary large parks found to offer minimal boundary-layer cooling. Contribution to cooling at the scale of the urban boundary-layer climate is attributed mainly to greenspace increasing surface roughness and thereby improving convection efficiency rather than evaporation. Although bluespace cooling and transport during the day can be substantial, nocturnal warming is highlighted as likely when conditions are most oppressive. However, when both features are employed together they can offer many synergistic ecosystem benefits including cooling. The ways in which green and bluespace infrastructure is applied in future urban growth strategies, particularly in countries expected to experience rapid urbanisation, warrants greater consideration in urban planning policy to mitigate the adverse effects of the UHI and enhance climate

Decreased survival of prostate cancer cells in vitro by combined treatment of heat and an antioxidant inhibitor diethyldithiocarbamate (DDC).

Science.gov (United States)

Moriyama-Gonda, Nobuko; Igawa, Mikio; Shiina, Hiroaki; Urakami, Shinji; Terashima, Masaharu

2003-11-01

The aim of this study was to examine a modulation of thermotolerance by treatment with combination of heat and the antioxidant inhibitor diethyldithiocarbamate (DDC) of the PC-3 prostate cancer cells. To determine thermotolerance, cells were heated once or twice. Two 1 h exposures at 43 degrees C, with a recovery period in between, revealed better survival/recovery of cells after the second exposure than after the first (fig. 1A + 1B). Additional experiments were performed, heating cells twice (fig. 1B + 1C). First, cells were heated at 43 degrees C for 1 h and, after various recovery times (intervals) at 37 degree C, subsequently reheated at 44 degrees C for 1 h. To ensure effective cell killing, efficiency of the combined treatments of 1 mM DDC and heating at 43 or 44 degrees C for 1 h was estimated by measuring cell survival, reactive oxygen species (ROS) generation, superoxide dismutase (SOD) activity and heat shock protein 70 (hsp 70) expression. To obtain a more effective method for subsequent heat exposure, cells were heated twice after a 24 h interval in the presence or absence of 1 mM DDC. ROS generation and SOD activity immediately increased correlating with duration of heating, but their levels gently decreased with time after discontinuation of heating. On the other hand, hsp 70 levels slowly increased, also correlating with duration of heating but continued to increase with time after discontinuation of heating for a certain period. DDC administration coupled with heating at 43 or 44 degrees C significantly decreased cell survival compared to heating alone (p DDC as compared to heat alone at 43 and 44 degrees C (p DDC could have potential benefits in the treatment of prostate cancer.

Municipal Development of Anaerobic Digestion/ Combined Heat and Power in Massachusetts

Science.gov (United States)

Pike, Brenda

With a commercial food waste ban going into effect in Massachusetts in October 2014, businesses, institutions, and municipalities are considering alternatives to landfills and incinerators for organic waste. Anaerobic digestion is one such alternative. Similar to composting, but in an environment devoid of oxygen, anaerobic digestion produces byproducts such as methane (which can be burned for heat or electricity) and liquid or solid digestate (which can be used as fertilizer, cattle bedding, and more). Thus, disposal of food waste and other organic materials can become a source of revenue rather than just an expense. Municipalities interested in developing anaerobic digestion/combined heat and power (AD/CHP) facilities have the benefit of desirable options for sites, such as landfill gas facilities and wastewater treatment plants, and potential feedstocks in source-separated residential or municipal food waste or wastewater. This thesis examines the opportunities and challenges for municipal development of AD/CHP facilities in Massachusetts.

Laboratory Evaluation of Gas-Fired Tankless and Storage Water Heater Approaches to Combination Water and Space Heating

Energy Technology Data Exchange (ETDEWEB)

Kingston, T. [Gas Technology Inst., Des Plaines, IL (United States); Scott, S. [Gas Technology Inst., Des Plaines, IL (United States)

2013-03-01

Homebuilders are exploring more cost-effective combined space and water heating systems (combo systems) with major water heater manufacturers that are offering pre-engineered forced air space heating combo systems. In this project, unlike standardized tests, laboratory tests were conducted that subjected condensing tankless and storage water heater based combo systems to realistic, coincidental space and domestic hot water loads and found that the tankless combo system maintained more stable DHW and space heating temperatures than the storage combo system, among other key findings.

Network Simulation solution of free convective flow from a vertical cone with combined effect of non- uniform surface heat flux and heat generation or absorption

Science.gov (United States)

Immanuel, Y.; Pullepu, Bapuji; Sambath, P.

2018-04-01

A two dimensional mathematical model is formulated for the transitive laminar free convective, incompressible viscous fluid flow over vertical cone with variable surface heat flux combined with the effects of heat generation and absorption is considered . using a powerful computational method based on thermoelectric analogy called Network Simulation Method (NSM0, the solutions of governing nondimensionl coupled, unsteady and nonlinear partial differential conservation equations of the flow that are obtained. The numerical technique is always stable and convergent which establish high efficiency and accuracy by employing network simulator computer code Pspice. The effects of velocity and temperature profiles have been analyzed for various factors, namely Prandtl number Pr, heat flux power law exponent n and heat generation/absorption parameter Δ are analyzed graphically.

Floodwater utilisation values of wetland services - a case study in Northeastern China

Science.gov (United States)

Lü, S. B.; Xu, S. G.; Feng, F.

2012-02-01

Water plays a significant role in wetlands. Floodwater utilisation in wetlands brings a wide range of wetland services, from goods production and water regulation to animal protection and aesthetics related to water supply in wetlands. In this study, the floodwater utilisation values of wetland services were estimated within the Momoge wetland and Xianghai wetland in western Jilin province of northeastern China. From 2003 to 2008, the floodwater diverted from the Nenjiang and Tao'er River is 381 million m3, which translates into a monetary value of approximately 1.35 billion RMB in 2008 (RMB: Chinese Currency, RMB 6.80 = US 1), and the ratio of economic value, eco-environmental value, and social value is 1:12:2. Besides the monetary value of the water itself, excessive floodwater utilisation may bring losses to wetlands; the threshold floodwater utilisation volumes in wetlands are discussed. Floodwater utilisation can alleviate water shortages in wetlands, and the evaluation of floodwater utilisation in wetland services in monetary terms is a guide for the effective use of the floodwater resources and for the conservation of wetlands.

The impact of viscosity on the combined heat, mass and momentum transfer in laminar liquid falling films

Science.gov (United States)

Mittermaier, M.; Ziegler, F.

2018-04-01

In this article we present a model describing a laminar film flow over a vertical isothermal plate whilst heat and mass transfer is occurring. We focus on a formulation where most common assumptions, such as constant property data and constant film thickness, have been cancelled. The hydrodynamic model results in longitudinal and transversal velocity components and their evolution in the entrance region. Heat and mass transfer occurs simultaneously and is modelled with respect to release of differential heat of solution as well as heat flow due to interdiffusion. The numerical solution is obtained by utilising a Newton-Raphson method to solve the finite difference formulation of the governing equations. Mass transfer across the film affects the development of both longitudinal and transversal velocity components. The hydrodynamics are modelled using a boundary layer approximation of the Navier-Stokes equations. The significance of simplifications on the hydrodynamic model are illustrated and discussed using a fully developed velocity profile (Nusselt flow) and a plug flow at the inlet for comparison. Even if a Nusselt profile is assumed, it develops further since mass is absorbed or desorbed. It is found that the onset of absorption occurs at shorter flow length when applying a plug flow at the inlet. If the film is initially in equilibrium, this results in a 9.3% increase in absorbed mass over a length of 0.03 m as compared with the Nusselt flow. A fluid with a viscosity five times the one of lithium bromide solution but sharing comparable properties apart from that, leads to lower overall heat and mass transfer rates. If the respective fluids are saturated at the inlet, the accumulated mass flux absorbed by lithium bromide solution is 2.2 times higher than the one absorbed by a high viscous fluid. However, when a plug flow is applied and the fluid is sub-cooled, ab initio the absorbed mass flux is slightly higher for a high viscous fluid. Assuming a sub

Dynamic modeling and evaluation of solid oxide fuel cell - combined heat and power system operating strategies

Science.gov (United States)

Nanaeda, Kimihiro; Mueller, Fabian; Brouwer, Jacob; Samuelsen, Scott

Operating strategies of solid oxide fuel cell (SOFC) combined heat and power (CHP) systems are developed and evaluated from a utility, and end-user perspective using a fully integrated SOFC-CHP system dynamic model that resolves the physical states, thermal integration and overall efficiency of the system. The model can be modified for any SOFC-CHP system, but the present analysis is applied to a hotel in southern California based on measured electric and heating loads. Analysis indicates that combined heat and power systems can be operated to benefit both the end-users and the utility, providing more efficient electric generation as well as grid ancillary services, namely dispatchable urban power. Design and operating strategies considered in the paper include optimal sizing of the fuel cell, thermal energy storage to dispatch heat, and operating the fuel cell to provide flexible grid power. Analysis results indicate that with a 13.1% average increase in price-of-electricity (POE), the system can provide the grid with a 50% operating range of dispatchable urban power at an overall thermal efficiency of 80%. This grid-support operating mode increases the operational flexibility of the SOFC-CHP system, which may make the technology an important utility asset for accommodating the increased penetration of intermittent renewable power.

Waste heat recovery options in a large gas-turbine combined power plant

Science.gov (United States)

Upathumchard, Ularee

This study focuses on power plant heat loss and how to utilize the waste heat in energy recovery systems in order to increase the overall power plant efficiency. The case study of this research is a 700-MW natural gas combined cycle power plant, located in a suburban area of Thailand. An analysis of the heat loss of the combustion process, power generation process, lubrication system, and cooling system has been conducted to evaluate waste heat recovery options. The design of the waste heat recovery options depends to the amount of heat loss from each system and its temperature. Feasible waste heat sources are combustion turbine (CT) room ventilation air and lubrication oil return from the power plant. The following options are being considered in this research: absorption chillers for cooling with working fluids Ammonia-Water and Water-Lithium Bromide (in comparison) and Organic Rankine Cycle (ORC) with working fluids R134a and R245fa. The absorption cycles are modeled in three different stages; single-effect, double-effect and half-effect. ORC models used are simple ORC as a baseline, ORC with internal regenerator, ORC two-phase flash expansion ORC and ORC with multiple heat sources. Thermodynamic models are generated and each system is simulated using Engineering Equation Solver (EES) to define the most suitable waste heat recovery options for the power plant. The result will be synthesized and evaluated with respect to exergy utilization efficiency referred as the Second Law effectiveness and net output capacity. Results of the models give recommendation to install a baseline ORC of R134a and a double-effect water-lithium bromide absorption chiller, driven by ventilation air from combustion turbine compartment. The two technologies yield reasonable economic payback periods of 4.6 years and 0.7 years, respectively. The fact that this selected power plant is in its early stage of operation allows both models to economically and effectively perform waste heat

Residential heat pumps in the future Danish energy system

DEFF Research Database (Denmark)

Petrovic, Stefan; Karlsson, Kenneth Bernard

2016-01-01

for politically agreed targets which include: at least 50% of electricity consumption from wind power starting from 2020, fossil fuel free heat and power sector from 2035 and 100% renewable energy system starting from 2050. Residential heat pumps supply around 25% of total residential heating demand after 2035......Denmark is striving towards 100% renewable energy system in 2050. Residential heat pumps are expected to be a part of that system.We propose two novel approaches to improve the representation of residential heat pumps: Coefficients of performance (COPs) are modelled as dependent on air and ground...... temperature while installation of ground-source heat pumps is constrained by available ground area. In this study, TIMES-DK model is utilised to test the effects of improved modelling of residential heat pumps on the Danish energy system until 2050.The analysis of the Danish energy system was done...

Sizing Combined Heat and Power Units and Domestic Building Energy Cost Optimisation

OpenAIRE

Dongmin Yu; Yuanzhu Meng; Gangui Yan; Gang Mu; Dezhi Li; Simon Le Blond

2017-01-01

Many combined heat and power (CHP) units have been installed in domestic buildings to increase energy efficiency and reduce energy costs. However, inappropriate sizing of a CHP may actually increase energy costs and reduce energy efficiency. Moreover, the high manufacturing cost of batteries makes batteries less affordable. Therefore, this paper will attempt to size the capacity of CHP and optimise daily energy costs for a domestic building with only CHP installed. In this paper, electricity ...

Evaluating combined effect of noise and heat on blood pressure changes among males in climatic chamber

OpenAIRE

Dehghan, Habibollah; Bastami, Mohamad Taghi; Mahaki, Behzad

2017-01-01

INTRODUCTION: Exposure to noise and heat causes individuals to experience some changes in the function of cardiovascular system in workplaces. This study aimed to find the combined effect of heat and noise on systolic and diastolic types of blood pressure in experimentally controlled conditions. METHODS: This quasi-experimental study was performed with 12 male students in a climatic chamber in 2014. Blood pressure including systolic and diastolic was measured in the following conditions: 15 m...

Combined generation of electric and heating energy in future development of Yugoslav energy sector until 2000

International Nuclear Information System (INIS)

Djajic, Nenad; Zivanovic, Vladimir

2000-01-01

Development of the district heating system in the FR Yugoslavia, beside the combined generation of electric and heating energy presents a necessity for energy, economic and ecological reasons. Although the structure of energy reserves is rather unfavourable considering that the lignite is being predominantly used, available reserves of energy raw material are able to ensure the long-term development of Yugoslav energy sector, and to offer real possibilities for considerable substitution of foreign good quality fuels, especially in district heating systems. Their further development will depend, among other things: on the implementation of new technological solutions for the exploitation of local energy resources; need of reconstruction, revitalisation and transformation of old condensing thermal power plants into the cogeneration plants; installation of remote controlled transmission of heating energy as well as on development of heating plants and smaller co-generation plants based on local energy resources. (Authors)

Simulation of a solar assisted combined heat pump – Organic rankine cycle system

International Nuclear Information System (INIS)

Schimpf, Stefan; Span, Roland

2015-01-01

Highlights: • Addition of an ORC to a solar thermal and ground source heat pump system. • Reverse operation of the scroll compressor in ORC mode. • Annual simulations for application in a single-family house at three locations. • By introducing the ORC the net electricity demand is reduced by 1–9%. • Over the lifetime of the system savings can cover additional investments. - Abstract: A novel solar thermal and ground source heat pump system that harnesses the excess heat of the collectors during summer by an Organic Rankine Cycle (ORC) is simulated. For the ORC the heat pump process is reversed. In this case the scroll compressor of the heat pump runs as a scroll expander and the working fluid is condensed in the ground heat exchanger. Compared to a conventional solar thermal system the only additional investments for the combined system are a pump, valves and upgraded controls. The goal of the study is to simulate and optimize such a system. A brief overview of the applied models and the evolutionary algorithm for the optimization is given. A system with 12 m 2 of flat plate collectors installed in a single family house is simulated for the locations Ankara, Denver and Bochum. The ORC benefits add up to 20–140 kW h/a, which reduces the net electricity demand of the system by 1–9%. Overall 180–520 € are saved over a period of 20 years, which can be enough to cover the additional investments

Heat and power from combustibles

International Nuclear Information System (INIS)

Zogg, M.

2002-01-01

This article compares four ways of generating heat and power from liquid and gaseous fuels. Various combinations of conventional boilers, heat pumps, combined heat and power units and combined-cycle power plants are considered and the ratio of heat to electrical power produced is discussed. Fuel requirements for the four combinations are looked at and net emissions of carbon dioxide, oxides of nitrogen and carbon monoxide presented in graphical form. The author makes recommendations on the choice of the technology to be used to generate heat and electricity for different heat/power ratios and criticises the all too slack emission limits for small combined heat and power units

High-performance nanostructured thermoelectric generators for micro combined heat and power systems

International Nuclear Information System (INIS)

Zhang, Yanliang; Wang, Xiaowei; Cleary, Martin; Schoensee, Luke; Kempf, Nicholas; Richardson, Joseph

2016-01-01

Highlights: • A TEG is fabricated using high-efficiency nanostructured thermoelectric materials. • The TEG produces high power density of 2.1 W/cm"2 with 5.3% electrical efficiency. • A micro-CHP system is demonstrated by integrating the TEG into a gas-fired boiler. - Graphical Abstract: - Abstract: Micro combined heat and power (micro-CHP) systems are promising pathways to increase power generation efficiencies. Here a new class of micro-CHP system without moving parts is experimentally demonstrated by integrating high-temperature thermoelectric generators (TEGs) and residential gas-fired boilers, thus enabling wide applications. The TEGs fabricated using high-efficiency nanostructured bulk half-Heusler alloys generate ultrahigh power density of 2.1 W/cm"2 with 5.3% electrical efficiency under 500 °C temperature differences between the hot and cold sides. The TEG system harnesses the untapped exergy between the combustion gas and water, and converts thermal energy into electric power with 4% heat-to-electricity efficiency based on the total heat input into the TEGs. The high-performance TEGs open lots of opportunities to transform power generation technologies and improve energy efficiency.

Biogas in Lusaka ? Feasibility study: Possibilities to extract and utilise biogas from municipal solid waste in Lusaka, Zambia

Energy Technology Data Exchange (ETDEWEB)

Hermansson, Emma; Nelson, Sara

2000-07-01

The objective of this study was to investigate possibilities to extract and utilise biogas from municipal solid waste in Lusaka, considering environmental, financial, technological and social aspects. The outcome provided three recommendations: 1 - a new landfill with biocells. The only legal tipping site in Lusaka has been condemned and there are plans for the construction of a new landfill. We recommend that the new site should be a sanitary landfill with full gas and leachate management. Thus, the costs for extracting biogas would be included in the investments for the landfill. It would be advisable to start with a simple end-use application during a running-in period when the technique and organisation is tested. Utilising the gas for internal heating or in a nearby industry will probably be the easiest and cheapest choice. 2 - a pilot project in a high-density area for co-dispersal of latrine and putrescibles. The sanitary conditions in high-density areas, where pit-latrines are the principal sanitary method, are insufficient. It is of great importance to master the situation in order to avoid further epidemics and water pollution. Compared to other solutions we consider a fermentation digester to be the best alternative. The main purpose for this pilot plant would, at least in the initial stage, be to investigate whether this method is a feasible solution for the problems with pit latrines. The aim of the end-use application could then merely be to demonstrate and inform the public about biogas. 3 - further investigations regarding the possibilities to extract and utilise biogas in industries and from manure, The estimated biogas potential from industries and manure and droppings from livestock and chickens is much bigger than from municipal solid waste and should be exploited. The end-use applications would probably be for internal use (heat and/or electricity). This was not investigated any further in our study.

An experimental investigation of heat transfer enhancement in minichannel: Combination of nanofluid and micro fin structure techniques

DEFF Research Database (Denmark)

Zhang, Ji; Diao, Yanhua; Zhao, Yaohua

2017-01-01

This work experimentally studied the single-phase heat transfer and pressure drop characteristics by using two heat transfer enhancement techniques (micro fin structure and nanofluids) in multiport minichannel flat tube (MMFT). MMFT consisted of numerous parallel rectangular minichannels...... and is widely used in industry as the heat transfer unit of a heat exchanger. Firstly, the enhanced heat transfer performances by individually using one enhancement technique were investigated by testing Nusselt number, friction factor and performance evaluation criterion (PEC). In this section, five MMFTs...... with different micro fin numbers (N = 0, 1, 2, 3 and 4) and nanofluids with three volume concentrations (φ = 0.005%, 0.01% and 0.1%) were used as test sections and working fluids respectively. Secondly, the experiments using two combined enhancement technique were performed. By using conjunctively two...

Enhanced detection of nitrogen dioxide via combined heating and pulsed UV operation of indium oxide nano-octahedra

Directory of Open Access Journals (Sweden)

Oriol Gonzalez

2016-10-01

Full Text Available We report on the use of combined heating and pulsed UV light activation of indium oxide gas sensors for enhancing their performance in the detection of nitrogen dioxide in air. Indium oxide nano-octahedra were synthesized at high temperature (900 °C via vapour-phase transport and screen-printed onto alumina transducers that comprised interdigitated electrodes and a heating resistor. Compared to the standard, constant temperature operation of the sensor, mild heating (e.g., 100 °C together with pulsed UV light irradiation employing a commercially available, 325 nm UV diode (square, 1 min period, 15 mA drive current signal, results in an up to 80-fold enhancement in sensitivity to nitrogen dioxide. Furthermore, this combined operation method allows for making savings in power consumption that range from 35% to over 80%. These results are achieved by exploiting the dynamics of sensor response under pulsed UV light, which convey important information for the quantitative analysis of nitrogen dioxide.

Enhanced detection of nitrogen dioxide via combined heating and pulsed UV operation of indium oxide nano-octahedra.

Science.gov (United States)

Gonzalez, Oriol; Roso, Sergio; Vilanova, Xavier; Llobet, Eduard

2016-01-01

We report on the use of combined heating and pulsed UV light activation of indium oxide gas sensors for enhancing their performance in the detection of nitrogen dioxide in air. Indium oxide nano-octahedra were synthesized at high temperature (900 °C) via vapour-phase transport and screen-printed onto alumina transducers that comprised interdigitated electrodes and a heating resistor. Compared to the standard, constant temperature operation of the sensor, mild heating (e.g., 100 °C) together with pulsed UV light irradiation employing a commercially available, 325 nm UV diode (square, 1 min period, 15 mA drive current signal), results in an up to 80-fold enhancement in sensitivity to nitrogen dioxide. Furthermore, this combined operation method allows for making savings in power consumption that range from 35% to over 80%. These results are achieved by exploiting the dynamics of sensor response under pulsed UV light, which convey important information for the quantitative analysis of nitrogen dioxide.

Emission operational strategy for combined cooling, heating, and power systems

International Nuclear Information System (INIS)

Fumo, Nelson; Mago, Pedro J.; Chamra, Louay M.

2009-01-01

Integrated Energy Systems (IES), as technology that use thermal activated components to recover waste heat, are energy systems that offer key solution to global warming and energy security through high overall energy efficiency and better fuel use. Combined Cooling, Heating, and Power (CCHP) Systems are IES that use recovered thermal energy from the prime mover to produce heating and cooling for the building. The CCHP operational strategy is critical and it has to be considered in a well designed system since it defines the ultimate goal for the benefits expected from the system. One of the most common operational strategies is the cost-oriented strategy, which allows the system to operate at the lowest cost. A primary energy strategy (PES) optimizes energy consumption instead of cost. However, as a result of the worldwide concern about global warming, projects that target reduction of greenhouse gas (GHG) emissions have gained a lot of interest. Therefore, for a CCHP system, an emission strategy (ES) would be an operational strategy oriented to minimize emission of pollutants. In this study, the use of an ES is proposed for CCHP systems targeted to reduce emission of pollutants. The primary energy consumption (PEC) reduction and carbon dioxide (CO 2 ) emission reduction obtained using the proposed ES are compared with results obtained from the use of a PES. Results show that lower emission of CO 2 is achieved with the ES when compared with the PES, which prove the advantage of the ES for the design of CCHP systems targeted to emissions reduction.

Influence of C-Peptide on Glucose Utilisation

Directory of Open Access Journals (Sweden)

B. Wilhelm

2008-01-01

Full Text Available During the recent years, multiple studies demonstrated that C-peptide is not an inert peptide, but exerts important physiological effects. C-peptide binds to cell membranes, stimulates the Na,K-ATPase and the endothelial nitric oxide (NO synthase. Moreover, there is evidence that C-peptide decreases glomerular hyperfiltration and increases glucose utilisation. Nevertheless, there is still limited knowledge concerning mechanisms leading to an increased glucose utilisation either in rats or in humans. The aim of this paper is to give an overview over the published studies regarding C-peptide and glucose metabolism from in vitro studies to longer lasting studies in humans.

Combined treatments of heat, irradiation, and pH effects on infectivity of foot-and-mouth disease virus in bovine tissues

International Nuclear Information System (INIS)

Lasta, J.; Blackwell, J.H.; Sadir, A.; Gallinger, M.; Marcoveccio, F.; Zamorano, M.; Ludden, B.; Rodriguez, R.

1992-01-01

Various traditional methods for processing meat products were examined for their virucidal effects on the A, O, and C serotypes of foot-and-mouth disease virus. Aging, curing, heating at 78 degrees C for 20 min or irradiation (1.5 Mrad, 2.4 Mrad) that did not alter the sensory characteristics of the product were used singly or in combination. The only processing treatment that was virucidal was the combination of heat and gamma irradiation

Modeling the heat transfer problem for the novel combined cryosurgery and hyperthermia system.

Science.gov (United States)

Zhao, Gang; Bai, Xue-Fei; Luo, Da-Wei; Gao, Da-Yong

2006-01-01

A multidimensional, finite element analysis (FEA) for the freezing, holding, rewarming and heating processes of biological tissues during the cryosurgery process of the new Combined Cryosurgery/Hyperthermia System is presented to theoretically test its validity. The tissues are treated as nonideal materials freezing over a temperature range, and the thermophysical properties of which are temperature dependent. The enthalpy method is applied to solve the highly nonlinear problem. It was found that when the same boundary condition and the same target tissue presented, the novel Cryosurgery/Hyperthermia System could supply the target tissue an approximative cooling rate, a much lower minimal temperature, a much greater warming rate, and a much greater thermal gradients compared with that of the simplified Endocare system. The numerical simulation indicates that the novel combined cryosurgery and hyperthermia system can provide an excellent curative effect in the corresponding cryotherapy. And the most attractive feature of this FEA framework is that it can be easily mastered by the surgeon without in-depth theory of heat transfer to analyze the cryosurgery process beforehand due to the friendly GUI (graphical user interface) of Ansys software.

The energy balance of utilising meadow grass in Danish biogas production

DEFF Research Database (Denmark)

Meyer, Ane Katharina Paarup; Raju, Chitra Sangaraju; Kucheryavskiy, Sergey V.

2015-01-01

of meadow areas, different relevant geo-datasets, spatial analyses, and various statistical analyses. The results show that values for the energy return on energy invested (EROEI) ranging from 1.7 to 3.3 can be obtained when utilising meadow grasses in local biogas production. The total national net energy......This paper presents a study of the energy balance of utilising nature conservation biomass from meadow habitats in Danish biogas production. Utilisation of nature conservation grass in biogas production in Denmark represents an interesting perspective for enhancing nature conservation of the open...... grassland habitats, while introducing an alternative to the use of intensively cultivated energy crops as co-substrates in manure based biogas plants. The energy balance of utilising nature conservation grass was investigated by using: data collected from previous investigations on the productivity...

Modulation of Antioxidant Defense System Is Associated with Combined Drought and Heat Stress Tolerance in Citrus

Directory of Open Access Journals (Sweden)

Sara I. Zandalinas

2017-06-01

Full Text Available Drought and high temperatures are two major abiotic stress factors that often occur simultaneously in nature, affecting negatively crop performance and yield. Moreover, these environmental challenges induce oxidative stress in plants through the production of reactive oxygen species (ROS. Carrizo citrange and Cleopatra mandarin are two citrus genotypes with contrasting ability to cope with the combination of drought and heat stress. In this work, a direct relationship between an increased antioxidant activity and stress tolerance is reported. According to our results, the ability of Carrizo plants to efficiently coordinate superoxide dismutase (SOD, ascorbate peroxidase (APX, catalase (CAT, and glutathione reductase (GR activities involved in ROS detoxification along with the maintenance of a favorable GSH/GSSG ratio could be related to their relative tolerance to this stress combination. On the other hand, the increment of SOD activity and the inefficient GR activation along with the lack of CAT and APX activities in Cleopatra plants in response to the combination of drought and heat stress, could contribute to an increased oxidative stress and the higher sensibility of this citrus genotype to this stress combination.

The Added Economic and Environmental Value of Solar Thermal Systems in Microgrids with CombinedHeat and Power

Energy Technology Data Exchange (ETDEWEB)

Marnay, Chris; Stadler, Michael; Cardoso, Goncalo; Megel, Olivier; Lai, Judy; Siddiqui, Afzal

2009-08-15

The addition of solar thermal and heat storage systems can improve the economic, as well as environmental attraction of micro-generation systems, e.g. fuel cells with or without combined heat and power (CHP) and contribute to enhanced CO2 reduction. However, the interactions between solar thermal collection and storage systems and CHP systems can be complex, depending on the tariff structure, load profile, etc. In order to examine the impact of solar thermal and heat storage on CO2 emissions and annual energy costs, a microgrid's distributed energy resources (DER) adoption problem is formulated as a mixed-integer linear program. The objective is minimization of annual energy costs. This paper focuses on analysis of the optimal interaction of solar thermal systems, which can be used for domestic hot water, space heating and/or cooling, and micro-CHP systems in the California service territory of San Diego Gas and Electric (SDG&E). Contrary to typical expectations, our results indicate that despite the high solar radiation in southern California, fossil based CHP units are dominant, even with forecast 2020 technology and costs. A CO2 pricing scheme would be needed to incent installation of combined solar thermal absorption chiller systems, and no heat storage systems are adopted. This research also shows that photovoltaic (PV) arrays are favored by CO2 pricing more than solar thermal adoption.

The Added Economic and Environmental Value of Solar Thermal Systems in Microgrids with CombinedHeat and Power

International Nuclear Information System (INIS)

Marnay, Chris; Stadler, Michael; Cardoso, Goncalo; Megel, Olivier; Lai, Judy; Siddiqui, Afzal

2009-01-01

The addition of solar thermal and heat storage systems can improve the economic, as well as environmental attraction of micro-generation systems, e.g. fuel cells with or without combined heat and power (CHP) and contribute to enhanced CO2 reduction. However, the interactions between solar thermal collection and storage systems and CHP systems can be complex, depending on the tariff structure, load profile, etc. In order to examine the impact of solar thermal and heat storage on CO2 emissions and annual energy costs, a microgrid's distributed energy resources (DER) adoption problem is formulated as a mixed-integer linear program. The objective is minimization of annual energy costs. This paper focuses on analysis of the optimal interaction of solar thermal systems, which can be used for domestic hot water, space heating and/or cooling, and micro-CHP systems in the California service territory of San Diego Gas and Electric (SDG and amp;E). Contrary to typical expectations, our results indicate that despite the high solar radiation in southern California, fossil based CHP units are dominant, even with forecast 2020 technology and costs. A CO2 pricing scheme would be needed to incent installation of combined solar thermal absorption chiller systems, and no heat storage systems are adopted. This research also shows that photovoltaic (PV) arrays are favored by CO2 pricing more than solar thermal adoption.

Combined heat and power system with advanced gasification technology for biomass wastes

Energy Technology Data Exchange (ETDEWEB)

Mochida, S.; Abe, T.; Yasuda, T. [Nippon Furnace Kogyo Kaisha Ltd, Yokohama (Japan); Gupta, A.K. [Maryland Univ., College Park, MD (United States). Dept. of Mechnical Engineering

2013-07-01

The results obtained from an advanced gasification system utilizing high temperature steam are presented here. The results showed successful demonstration of clean syngas production having high calorific value fuel ({proportional_to}10 MJ/m{sup 3}N) using woody biomass wastes in a downdraft type gasifier. The gasification capacity of the plant on dry basis was 60 kg/h. The syngas produced can be utilized in an absorption type chiller for air conditioning. This advanced gasification technology allows one to transform wastes to clean energy at local production sites without any environmental impact and expensive waste transportation costs. The experience gained from the demonstration plant allows one to implement to other industrial applications for use as a decentralized unit and obtain clean syngas for local use. The demonstration conducted here shows that the system is favorable for onsite use of compatible combined heat and power (CHP) system including light oil supported diesel engine power generator. The biomass waste fuel from a lumber mill factory was used in this study. The factory handles a wide forests area of about 50 ha and produces about 2,500 m{sup 3}/year of wood chips from thin out trees and waste lumbers. This translates to a maximum 110 kg/h of wood chips that can be fed to a gasifier. The syngas produced was used for the combined heat and power system. Local use of biomass for fuel reforming reduces the cost of collection and transportation costs so that a sustainable business is demonstrated with profit from the generated electricity and thermal energy. The cost structure incorporates both the depreciation cost and operation cost of the system. Thermal energy from hot water can be used for drying lumbers and wood chips in a cascade manner. The drying process can be adopted for enhancing its productivity with increased variability on the quality of lumber. The results show that the combined heat and power system (CHP) offers good profitable

Comparative and Combinative Study of Urban Heat island in Wuhan City with Remote Sensing and CFD Simulation

Directory of Open Access Journals (Sweden)

Zhuang Yu

2008-10-01

Full Text Available Urban heat islands are one of the most critical urban environment heat problems. Landsat ETM+ satellite data were used to investigate the land surface temperature and underlying surface indices such as NDVI and NDBI. A comparative study of the urban heat environment at different scales, times and locations was done to verify the heat island characteristics. Since remote sensing technology has limitations for dynamic flow analysis in the study of urban spaces, a CFD simulation was used to validate the improvement of the heat environment in a city by means of wind. CFD technology has its own shortcomings in parameter setting and verification, while RS technology is helpful to remedy this. The city of Wuhan and its climatological condition of being hot in summer and cold in winter were chosen to verify the comparative and combinative application of RS with CFD in studying the urban heat island.

Swiss energy research program on heat-pumps, combined heat and power and refrigeration for 2008-2011; Energieforschungsprogramm. Waermepumpen, Waerme-Kraft-Kopplung, Kaelte fuer die Jahre 2008-2011

Energy Technology Data Exchange (ETDEWEB)

Kopp, T. [Hochschule fuer Technik HSR, Rapperswil (Switzerland); Eckmanns, A. [Swiss Federal Office of Energy (OFEN), Berne (Switzerland)

2009-07-15

This report published by the Swiss Federal Office of Energy (SFOE) takes a look at the research programme on heat-pumps, combined heat and power and refrigeration for the years 2008 - 2011. Work proposed for the years 2008 - 2011 involves the following topics: Improvement of components and the thermodynamic cycles of heat pumps and refrigeration plants as well as the improvements in the efficiency of cogeneration plants and the reduction of emission of pollutants. Also, the overall optimisation of total systems is to be examined. Highly-efficient systems for sanitary hot water production are to be looked at, as are miniaturisation and new solutions for the installation of heating and cooling systems with heat pumps. Also the development of environmental-friendly working fluids for heat pumps and refrigeration plants is planned. Pilot and demonstration projects are also to be supported in all areas.

The combined effect of heat and gamma irradiation on the inactivation of selected microorganisms associated with food hygiene

International Nuclear Information System (INIS)

Kwon, O.J.; Byun, M.W.

1996-01-01

The bactericidal effectiveness of radiation alone or in combination with heat against 8 strains associated with food hygiene were evaluated. In the case of radiation alone, D values of micro-organisms were 0.14~0.48 kGy, and inactivation factors were 4.54~21.43 at the doses of 2~3 kGy. Escherichia coli was the most sensitive among the tested strains, resulting in a D value of 0.14 kGy. D values of tile strains were 10~40 minutes at 50±1°C and 5~10 minutes at 60±1°C. Combination with heat and radiation showed D values of 0.04~0.31. Inactivation factors were 6.45~75 at the doses of 2 to 3 kGy. Therefore, heat treatment prior to irradiation significantly increased activation rate by increasing radiation sensitivity of microorganisms

Optimal Energy Management of Combined Cooling, Heat and Power in Different Demand Type Buildings Considering Seasonal Demand Variations

Directory of Open Access Journals (Sweden)

Akhtar Hussain

2017-06-01

Full Text Available In this paper, an optimal energy management strategy for a cooperative multi-microgrid system with combined cooling, heat and power (CCHP is proposed and has been verified for a test case of building microgrids (BMGs. Three different demand types of buildings are considered and the BMGs are assumed to be equipped with their own combined heat and power (CHP generators. In addition, the BMGs are also connected to an external energy network (EEN, which contains a large CHP, an adsorption chiller (ADC, a thermal storage tank, and an electric heat pump (EHP. By trading the excess electricity and heat energy with the utility grid and EEN, each BMG can fulfill its energy demands. Seasonal energy demand variations have been evaluated by selecting a representative day for the two extreme seasons (summer and winter of the year, among the real profiles of year-round data on electricity, heating, and cooling usage of all the three selected buildings. Especially, the thermal energy management aspect is emphasized where, bi-lateral heat trading between the energy supplier and the consumers, so-called energy prosumer concept, has been realized. An optimization model based on mixed integer linear programming has been developed for minimizing the daily operation cost of the EEN while fulfilling the energy demands of the BMGs. Simulation results have demonstrated the effectiveness of the proposed strategy.

Thermoeconomic Analysis of Hybrid Power Plant Concepts for Geothermal Combined Heat and Power Generation

Directory of Open Access Journals (Sweden)

Florian Heberle

2014-07-01

Full Text Available We present a thermo-economic analysis for a low-temperature Organic Rankine Cycle (ORC in a combined heat and power generation (CHP case. For the hybrid power plant, thermal energy input is provided by a geothermal resource coupled with the exhaust gases of a biogas engine. A comparison to alternative geothermal CHP concepts is performed by considering variable parameters like ORC working fluid, supply temperature of the heating network or geothermal water temperature. Second law efficiency as well as economic parameters show that hybrid power plants are more efficient compared to conventional CHP concepts or separate use of the energy sources.

Critical factors for profitable combined production of heat, power and biofuels; Kritiska faktorer foer loensam produktion i bioenergikombinat

Energy Technology Data Exchange (ETDEWEB)

Nohlgren, Ingrid; Gunnarsson, Emma; Lundqvist, Per; Stigander, Haakan; Widmark, Annika (AaF, Stockholm (Sweden))

2012-02-15

During the last 5-10 years, research and development efforts have been made in the field of polygeneration of heat and power with production of 'other green' products such as transport fuels or wood pellets. The driving force for heat and power producers is the potential of increased profitability through additional sales of heat. The driving force for wood pellet and some transport fuel producers is the potential of low cost process steam or heat. However, in the case of gasification based transport fuel production processes the situation is different. The process generates a surplus of heat, which can benefit from the proximity of a district heating net. In addition, some polygeneration combinations could provide other advantages such as more efficient raw material handling. Together with these driving forces, the EU renewable energy directive (which targets 10 % renewable energy use in the transport sector by 2020), shows that the market for production of renewable transport fuel is expanding. To refine Swedish biomass resources to more highly valuable products such as wood pellets or renewable transport fuels would maintain industry and employment opportunities within Sweden and at the same time fulfils the international and national climate targets. The overall aim with this project is to describe the factors which are crucial for the opportunity for profitable polygeneration of heat, power and wood pellets or renewable transport fuels and how these factors influence the location of such a plant within Sweden. The important factors can be categorized as: (1) Supply of raw material, (2) distribution of raw material and products, (3) Demand of products and (4) Integration between the different plants. In this project, only general aspects are described and should be seen as guidance for the industry (both energy and forest industry) which has an interest in polygeneration. The project gives an overview of different possibilities, opportunities and

A comparison of combined heat and power feasibility models

Energy Technology Data Exchange (ETDEWEB)

Hinojosa, L.R.; Day, A.R.; Maidment, G.G. [Department of Engineering Systems, Faculty of Engineering, Science and the Built Environment, London South Bank University, 103 Borough Road, London SE1 0AA (United Kingdom); Dunham, C.; Kirk, P. [SEA/RENUE, 42 Braganza Street, London SE17 3RJ (United Kingdom)

2007-09-15

Carrying out feasibility studies for combined heat and power (CHP) in buildings systems is one of the most important steps in the decision-making process. This paper compares the features of different software packages available in the market and some custom-built models. It also discusses the advantages and disadvantages of building one's own application. The number of variables that need to be considered will depend on the level of accuracy and flexibility sought. Software packages are a good start, but they tend to be either overly simple or extremely complicated, and sometimes not very flexible. On the other hand, building custom-built generic models that include different technologies, unit sizes, control modes, market restrictions and benefits, can be a complex and laborious process, but will be more transparent to the user. (author)

Heat Transfer Computations of Internal Duct Flows With Combined Hydraulic and Thermal Developing Length

Science.gov (United States)

Wang, C. R.; Towne, C. E.; Hippensteele, S. A.; Poinsatte, P. E.

1997-01-01

This study investigated the Navier-Stokes computations of the surface heat transfer coefficients of a transition duct flow. A transition duct from an axisymmetric cross section to a non-axisymmetric cross section, is usually used to connect the turbine exit to the nozzle. As the gas turbine inlet temperature increases, the transition duct is subjected to the high temperature at the gas turbine exit. The transition duct flow has combined development of hydraulic and thermal entry length. The design of the transition duct required accurate surface heat transfer coefficients. The Navier-Stokes computational method could be used to predict the surface heat transfer coefficients of a transition duct flow. The Proteus three-dimensional Navier-Stokes numerical computational code was used in this study. The code was first studied for the computations of the turbulent developing flow properties within a circular duct and a square duct. The code was then used to compute the turbulent flow properties of a transition duct flow. The computational results of the surface pressure, the skin friction factor, and the surface heat transfer coefficient were described and compared with their values obtained from theoretical analyses or experiments. The comparison showed that the Navier-Stokes computation could predict approximately the surface heat transfer coefficients of a transition duct flow.

Utilisation of the energy-independent underground gasification-uvea process for carbamide production; Einsatz des energieautarken Untertagevergasungs-Urea-Prozesses zur Carbamid-Herstellung

Energy Technology Data Exchange (ETDEWEB)

Nakaten, Natalie; Kempka, Thomas [Helmholtz Zentrum Potsdam, Deutsches GeoForschungszentrum (GFZ) Potsdam (Germany); Schlueter, Ralph [DMT GmbH und Co. KG, Essen (Germany). Abt. Geologie und Bohrlochvermessungen; Hamann, Joerg [EPC Industrial Engineering Deutschland GmbH, Alzenau (Germany); Islam, Rafiqul [Dhaka Univ. (Bangladesh). Dept. of Applied Chemistry and Chemical Engineering; Azzam, Rafig [RWTH Aachen (Germany). Lehrstuhl fuer Ingenieur- und Hydrogeologie

2011-08-15

The worldwide coal resources have an energy supply potential of several hundred years. However, great depths, thin seams and tectonic faults may greatly restrict the utilisation of the coal seams by means of conventional conveyor technologies. With the aim of production of a conveyable synthesis gas underground coal gasification (UCG) offers an environmentally friendly and economically viable possibility of utilisation of previously inaccessible coal deposits. The high-calorific UCG synthesis gas can be used, for example, for the generation of electricity in an integrated gas and steam turbine process (GaS) as well as the production of chemical starting materials. One possibility of product recovery from the UCG synthesis gas is the production of the fertiliser carbamide (CH{sub 6}N{sub 2}O{sub 2}). The aim of this study is the development of a utilisation concept for coal deposits on the basis of a combined and energy-independent UCG-GaS-urea process. To check the utilisation concept based on an independent electricity supply an economic feasibility study for a selected investigation area in the north of Bangladesh was carried out with consideration of the economic viability and potential of the UCG-GaS-urea process. (orig.)

Two-stage absorber systems - Economically viable combined heat and cold generation; Wirtschaftlicher Kraft-Waerme-Kaelte-Verbund

Energy Technology Data Exchange (ETDEWEB)

Biniossek, H. [Giesecke und Devrient, Muenchen (Germany); Schmid, W. [Technische Gebaeudeausruestung, Muenchen (Germany)

2008-07-01

This article takes a look at how the possibilities of optimising power, heat and cold generation for the German Giesecke and Devrient company were examined and implemented. The company, which produces banknotes and chip-cards, chose the combination of a Combined Heat and Power (CHP) Unit and a two-stage absorber refrigeration system. The company's old system is briefly described and the reasons for replacing it are discussed. The careful dimensioning of the new system and the search for appropriate equipment are described. Intelligent power flows and a cooling system with two different temperature levels are described. Costs saved and emergency power generation are also looked at, as are the complex demands placed on the control of the system. The system's functioning is briefly described.

Preliminary project concerning the straw-fueled combined power-heat plant to be constructed at Glamsbjerg

International Nuclear Information System (INIS)

Gabriel, S.; Koch, T.

1994-06-01

Power and heat generation based on biomass gasification is of great importance due to its beneficial environmental effects and good economy. This report concerns a preliminary project on feasibility and problems of implementing a dual-purpose power plant, supplying both power and district heating to several schools, swimming pools and other public facilities at Glamsbjerg (Funen). The plant is to be based on thermal gasification (pyrolysis) of straw and use of the gas in a diesel engine. The diesels operate the power generator, and their waste heat should be utilized in the local district heating network. In order to establish a stable and flexible straw supply to the plant an evaluation of resources in the area has been carried out. Apart from straw-derived fuel the plant is planned to use natural gas for start and maintenance of the process. The prices of the combined plant and of the fuel processing are estimated in the report. (EG)

Glucose utilisation in the lungs of septic rats

International Nuclear Information System (INIS)

Hansson, L.; Jeppsson, B.; Ohlsson, T.; Sandell, A.; Valind, S.; Luts, A.; Wollmer, P.

1999-01-01

Sequestration and degranulation of leucocytes in the pulmonary microcirculation is considered to be a key event in the development of acute respiratory distress syndrome in patients with sepsis. Glucose serves as the main source of energy in activated leucocytes. The aim of this study was to assess whether glucose utilisation in the lungs can be used as an indicator of pulmonary leucocyte accumulation in an experimental model of sepsis of intra-abdominal origin. Sepsis was induced in rats by abdominal implantation of a gelatine capsule containing bacteria and rat colonic contents. Empty gelatine capsules were implanted in control animals. Animals were studied 6 and 12 h after sepsis induction. Glucose utilisation was measured as the tissue uptake of fluorine-18-fluorodeoxyglucose ( 18 FDG) 1 h after intravenous injection of the tracer. Micro-autoradiography was also performed after injection of tritiated deoxyglucose. We found increased uptake of 18 FDG in the lungs of septic animals. The uptake also increased with time after sepsis induction. 18 FDG uptake in circulating leucocytes was increased in septic animals compared with controls, and micro-autoradiography showed intense accumulation of deoxyglucose in leucocytes in the lungs of septic animals. We conclude that glucose utilisation is increased in the lungs of septic rats. Measurements of pulmonary glucose utilisation as an index of leucocyte metabolic activity may open new possibilities for studies of the pathophysiology of sepsis and for evaluation of therapeutic interventions. (orig.)

Power generation efficiency of an SOFC-PEFC combined system with time shift utilization of SOFC exhaust heat

Energy Technology Data Exchange (ETDEWEB)

Obara, Shin' ya [Power Engineering Lab., Department of Electrical and Electronic Engineering, Kitami Institute of Technology, 165 Kouen-cho, Kitami, Hokkaido 0908507 (Japan)

2010-01-15

A microgrid, with little environmental impact, is developed by introducing a combined SOFC (solid oxide fuel cell) and PEFC (proton exchange membrane fuel cell) system. Although the SOFC requires a higher operation temperature compared to the PEFC, the power generation efficiency of the SOFC is higher. However, if high temperature exhaust heat may be used effectively, a system with higher total power generation efficiency can be built. Therefore, this paper investigates the operation of a SOFC-PEFC combined system, with time shift operation of reformed gas, into a microgrid with 30 houses in Sapporo, Japan. The SOFC is designed to correspond to base load operation, and the exhaust heat of the SOFC is used for production of reformed gas. This reformed gas is used for the production of electricity for the PEFC, corresponding to fluctuation load of the next day. Accordingly, the reformed gas is used with a time shift operation. In this paper, the relation between operation method, power generation efficiency, and amount of heat storage of the SOFC-PEFC combined system to the difference in power load pattern was investigated. The average power generation efficiency of the system can be maintained at nearly 48% on a representative day in February (winter season) and August (summer season). (author)

System factors influencing utilisation of Research4Life databases by ...

African Journals Online (AJOL)

This is a comprehensive investigation of the influence of system factors on utilisation of Research4Life databases. It is part of a doctoral dissertation. Research4Life databases are new innovative technologies being investigated in a new context – utilisation by NARIs scientists for research. The study adopted the descriptive ...

Combined action of S-carvone and mild heat treatment on Listeria monocytogenes Scott A

NARCIS (Netherlands)

Karatzas, A.K.; Bennik, M.H.J.; Smid, E.J.; Kets, E.P.W.

2000-01-01

The combined action of the plant-derived volatile, S-carvone, and mild heat treatment on the food-borne pathogen, Listeria monocytogenes, was evaluated. The viability of exponential phase cultures grown at 8 °C could be reduced by 1.3 log units after exposure to S-carvone (5 mmol 1-1) for 30 min at

Thermoeconomic Optimization of a Combined Heating and Humidification Coil for HVAC Systems

Science.gov (United States)

Teodoros, Liliana; Andresen, Bjarne

2016-07-01

The total cost of ownership is calculated for a combined heating and humidification coil of an air-handling unit taking into account investment and operation costs simultaneously. This total cost represents the optimization function for which the minimum is sought. The parameters for the cost dependencies are the physical dimensions of the coil: length, width and height. The term "coil" is used generically since in this setup it generates heating as well as humidification in a single unit. The first part of the paper deals with the constructive optimization and finds the relationship between the dimensions for a minimum cost. The second part of the paper takes the results of the constructive optimization further and, based on the data derived in our previous papers, analyzes the minimum total cost for the humidification coil while balancing the amount of water used to humidify the air and modify its temperature.

An evaluation of the potential of combination processes involving heat and irradiation for food preservation

International Nuclear Information System (INIS)

Shamsuzzaman, K.; Payne, B.; Cole, L.; Goodwin, M.; Borsa, J.

1989-11-01

Effects of combined heating and gamma radiation on Clostridium sporogenes spores and Salmonella seftenberg were examined. The order in which irradiation and heat were applied had a profound effect on the survival of the organisms. Heating of C.sporogenes spores at 95 degrees Celsius had very little effect on their sensitivity to subsequent irradiation, but irradiation of the spores at 0 degrees Celsius increased their sensitivity to subsequent heat treatment and thus reduced their heat D 10 values (time required to activate the spores to 10% of their initial number). This radiation-induced heat sensitivity increased with the increase in radiation dose. The Z values (change in temperature required for a tenfold change in D 10 values) of the spores were found to increase with the increase in pre-irradiation dose. Radiation-induced heat sensitivity was found to persist for at least 35 days in spores irradiated in frozen or freeze-dried states in distilled water or in phosphate buffer suspensions, and for at least 14 days in a number of food slurries. In phosphate buffer and nutrient broth suspensions, the radiation-heat synergism decreased with increasing pH of the media from pH 4.7 to pH 7.5. However, the effect of pH on synergism was less pronounced in spores suspended in some food slurries. Preliminary results indicate that pre-irradiation of S. senftenberg at 0.5 kGy did not change the heat sensitivity of this organism at 52 degrees Celsius, but when radiation and heat were applied simultaneously, synergistic inactivation was observed even at 50 degrees Celsius. Practical implications of these results are discussed

The potential demand for bioenergy in residential heating applications (bio-heat) in the UK based on a market segment analysis

International Nuclear Information System (INIS)

Jablonski, S.; Pantaleo, A.; Bauen, A.; Pearson, P.; Panoutsou, C.; Slade, R.

2008-01-01

How large is the potential demand for bio-heat in the UK? Whilst most research has focused on the supply of biomass for energy production, an understanding of the potential demand is crucial to the uptake of heat from bioenergy. We have designed a systematic framework utilising market segmentation techniques to assess the potential demand for biomass heat in the UK. First, the heat market is divided into relevant segments, characterised in terms of their final energy consumption, technological and fuel supply options. Second, the key technical, economic and organisational factors that affect the uptake of bioenergy in each heat segment are identified, classified and then analysed to reveal which could be strong barriers, which could be surmounted easily, and for which bioenergy heat represents an improvement compared to alternatives. The defined framework is applied to the UK residential sector. We identify provisionally the most promising market segments for bioenergy heat, and their current levels of energy demand. We find that, depending on the assumptions, the present potential demand for bio-heat in the UK residential sector ranges between 3% (conservative estimate) and 31% (optimistic estimate) of the total energy consumed in the heat market. (author)

Design for micro-combined cooling, heating and power systems stirling engines and renewable power systems

CERN Document Server

2015-01-01

‘Design for Micro-Combined Cooling, Heating & Power Systems’ provides a manual for the technical and structural design of systems for supplying decentralised energy in residential buildings. It presents the micro-combined cooling, heating & power systems Stirling engines & renewable energy sources (mCCHP-SE-RES) systems in an accessible manner both for the public at large, and for professionals who conceive, design or commercialise such systems or their components.  The high performance levels of these systems are demonstrated within the final chapter by the results of an experiment in which a house is equipped with a mCCHP-SE-RES system. The reader is also familiarized with the conceptual, technical and legal aspects of modern domestic energy systems; the components that constitute these systems; and advanced algorithms for achieving the structural and technical design of such systems. In residential buildings, satisfying demands of durable development has gradually evolved from necessity to...

Combining the pressure effect with local heat treatment for improving the sheet metal forming process

Science.gov (United States)

Palumbo, G.; Piccininni, A.; Guglielmi, P.; Sorgente, D.; Tricarico, L.

2016-08-01

The present work deals with the advantages in the Hydromechanical Deep Drawing (HDD) when AA5754 Tailored Heat Treated Blanks (THTBs) are adopted. It is well known that the creation of a suitable distribution of material properties increases the process performance. When non heat-treatable alloys are considered, the THTB approach can be successfully applied to increase the Limit Drawing Ratio (LDR) by changing the peripheral zone into the annealed state starting from a cold-worked blank. If this approach is combined with the advantages of a counterpressure, even more remarkable improvements can be achieved. Due to the large number of involved parameters, the optimized design of both the local treatment and the pressure profile were investigated coupling an axial symmetric Finite Element model with the integration platform modeFRONTIER. Results confirmed the possibility of increasing the LDR from 2.0 (Deep Drawing using a blank in the annealed state) up to about 3.0 if combining the adoption of a THTB with the optimal pressure profile.

Effects of combined heat and ionizing radiation on thiamine (Vitamin B1) content in model systems and food matrices

International Nuclear Information System (INIS)

Chuaqui-Offermanns, N.; Shoemaker, L.; McDougall, T.

1989-01-01

The effects of heat and radiation on thiamine stability are being studied both singly and in combination. Heat, γ-radiation and a combination of them were applied to a model system consisting of 2 x 10 -5 M thiamine hydrochloride in 0.01N HCl (pH=2.5), and their effects are reported. The effects of these two agents on thiamine in two food matrices, concentrated orange juice and green peas, are also reported. Heat was not found to have a significant effect on thiamine in the model system at temperatures up to 120 0 C for up to 60 min of treatment. A small, but significant heat effect was found in the two foods. The retention of thiamine in the model system and in the two foods decreased exponentially as the radiation dose increased. The degradation of thiamine by γ-radiation in both foods was a factor of 10 less than that observed in the model system. A small, but significant synergistic effect was found when samples of the model system were heated at 120 0 C for one hour 24 h after irradiation. (author)

Factors affecting Japanese retirees' healthcare service utilisation in Malaysia: a qualitative study.

Science.gov (United States)

Kohno, Ayako; Nik Farid, Nik Daliana; Musa, Ghazali; Abdul Aziz, Norlaili; Nakayama, Takeo; Dahlui, Maznah

2016-03-22

While living overseas in another culture, retirees need to adapt to a new environment but often this causes difficulties, particularly among those elderly who require healthcare services. This study examines factors affecting healthcare service utilisation among Japanese retirees in Malaysia. We conducted 6 focus group discussions with Japanese retirees and interviewed 8 relevant medical services providers in-depth. Guided by the Andersen Healthcare Utilisation Model, we managed and analysed the data, using QSR NVivo 10 software and the directed content analysis method. We interviewed participants at Japan Clubs and their offices. 30 Japanese retirees who live in Kuala Lumpur and Ipoh, and 8 medical services providers. We identified health beliefs, medical symptoms and health insurance as the 3 most important themes, respectively, representing the 3 dimensions within the Andersen Healthcare Utilisation Model. Additionally, language barriers, voluntary health repatriation to Japan and psychological support were unique themes that influence healthcare service utilisation among Japanese retirees. The healthcare service utilisation among Japanese retirees in Malaysia could be partially explained by the Andersen Healthcare Utilisation Model, together with some factors that were unique findings to this study. Healthcare service utilisation among Japanese retirees in Malaysia could be improved by alleviating negative health beliefs through awareness programmes for Japanese retirees about the healthcare systems and cultural aspects of medical care in Malaysia. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Analysis of an optimal resorption cogeneration using mass and heat recovery processes

International Nuclear Information System (INIS)

Lu, Yiji; Wang, Yaodong; Bao, Huashan; Yuan, Ye; Wang, Liwei; Roskilly, Anthony Paul

2015-01-01

Highlights: • Resorption cogeneration for electricity and refrigeration generation. • Mass and heat recovery to further improve the performance. • The first and second law analysis. - Abstract: This paper presents an optimised resorption cogeneration using mass and heat recovery to improve the performance of a novel resorption cogeneration fist proposed by Wang et al. This system combines ammonia-resorption technology and expansion machine into one loop, which is able to generate refrigeration and electricity from low-grade heat sources such as solar energy and industrial waste heat. Two sets of resorption cycle are designed to overcome the intermittent performance of the chemisorption and produce continuous/simultaneous refrigeration and electricity. In this paper, twelve resorption working pairs of salt complex candidates are analysed by the first law analysis using Engineering Equation Solver (EES). The optimal resorption working pairs from the twelve candidates under the driven temperature from 100 °C to 300 °C are identified. By applying heat/mass recovery, the coefficient of performance (COP) improvement is increased by 38% when the high temperature salt (HTS) is NiCl 2 and by 35% when the HTS is MnCl 2 . On the other hand, the energy efficiency of electricity has also been improved from 8% to 12% with the help of heat/mass recovery. The second law analysis has also been applied to investigate the exergy utilisation and identify the key components/processes. The highest second law efficiency is achieved as high as 41% by the resorption working pair BaCl 2 –MnCl 2 under the heat source temperature at 110 °C.

Application of combined heat and power in Malaysia Industrial Sector

International Nuclear Information System (INIS)

Zaredah Hashim; Faridah Mohd Taha

2010-01-01

Malaysia is still working on continuing its economic growth especially in the industrial sector in order to achieve vision 2020. The rapid industrialization process has caused increment in the energy demand, which simultaneously increases carbon dioxide (CO 2 ) emissions. Energy efficient technologies are strongly needed for reducing the energy requirement and to avoid the depleting of energy resources. This project focused on the application of integrated resource planning (IRP) in industrial sector using Combined Heat and Power (CHP), as a strategy for Demand Side Management (DSM). This approach is another way for meeting near and future energy requirement in Malaysia's industrial sector. Two scenarios which are Business As Usual (BAU) and CHP were developed using End Use Model EUM), to forecast the energy demand and CO 2 emission in Malaysia's industries. The effectiveness of the proposed method is then simulated using Long Range Energy Alternative Planning System (LEAP) software and Comparative Model for Projects of Engineering Economics and Energy Environmental Development (COMPEED) analysis. Evaluations were based on the potential of energy saving and CO 2 reduction. Scope of research was limited to pulp and paper industrial sub sector. The research data were extracted from Energy Audit Reports conducted by Malaysia Energy Center (PTM). An engineering calculation was demonstrated. Two designs of CHP applications for the pulp and paper industrial sector are according to heating and electricity sizing. It was found that the most energy efficient and CO 2 reduction for Malaysia's industrial sector is the CHP based on heating requirement. The method was found to be able of save fuel and GHG emission compared to the reference case. (author)

Increasing utilisation of district heating through absorption cooling technology; Oekat fjaerrvaermeutnyttjande med hjaelp av absorptionstekniken

Energy Technology Data Exchange (ETDEWEB)

Bjurstroem, Henrik; Ingvarsson, Paul; Zinko, Heimo

2010-10-15

The purpose of the research project presented in this report was to find ways to return a lower temperature from the generator of the chillers in a supply/return connection. The initial target is 40 deg C. Ideally, the absorption chiller and possible ulterior uses of the remaining heat in the heat carrier (the water flowing through the generator) should be as close as possible to a pure heat load. The hot-water driven absorption chillers used today to produce cooling in DH networks are exclusively so-called single-effect (Sweden) chillers with water and lithium bromide as working pair. This study aims at raising as much as possible the upper bounds on the absorption chiller capacity that may be connected to a DH network, by lowering the temperature at the outlet. To this end, several approaches have been used: - A search for alternative designs of the absorption chiller, focusing on commercially available and tested technology, both those yielding a large temperature decrease over the generator and those that may be operated at lower temperatures than the conventional solutions; - An examination of the impact of further uses of the remaining heat on temperature in the return line. larger. Smaller units are considered only if they can be used to illustrate a principle. As a complement to this investigation, a few other issues have been treated: - What temperature levels should a system actually be designed for? - The LAVA method to calculate the impact of supply and return temperatures in the DH network on the economics of power production is presented; - Interesting technical solutions using desiccant-aided evaporative cooling are shortly described; - The modern developments in the field of working pairs (refrigerant and absorbent) are reviewed. Assumptions made here are that there is a significant demand for cooling, and that the demand is large enough to justify operating the cogeneration plant at a load level exceeding its lowest acceptable part load rather than

Evaluation of transcatheter arterial chemoembolization combined with radiofrequency capacitive heating on clinical therapeutic effect of metastatic carcinoma

International Nuclear Information System (INIS)

Chen Qianli; Ye Qiang; Gu Weizhong; Zhang Jiazhong; Tong Qiangang; Xi Shunfa

2006-01-01

Objective: To evaluate clinical therapeutic efficacy and adverse efficacy of transcatheter arterial chemoembolization (TACE) combined with radiofrequency capacitive heating (RCH) for metastatic hepatic carcinoma (MHC). Methods: Thirty-nine cases of MHC were enrolled in this study and divided into two groups: study group (n=19) and control group (n=20). Before therapy, the Karnofsky's score of the patients was all beyond 60. Results: The carcinoma growth rate of the study group was -(0.38±0.22), while that of the control group was -(0.13±0.25), showing significant statistical difference (P 0.05). Conclusion: The therapeutic effect of MHC can be further improved by the treatment of TACE combined with radiofrequency capacitive heating without increase of adverse side effects. (authors)

Potentialities and type of integrating nuclear heating stations into district heating systems

International Nuclear Information System (INIS)

Munser, H.; Reetz, B.; Schmidt, G.

1978-01-01

Technical and economical potentialities of applying nuclear heating stations in district heating systems are discussed considering the conditions of the GDR. Special attention is paid to an optimum combination of nuclear heating stations with heat sources based on organic fuels. Optimum values of the contribution of nuclear heating stations to such combined systems and the economic power range of nuclear heating stations are estimated. Final considerations are concerned with the effect of siting and safety concepts of nuclear heating stations on the structure of the district heating system. (author)

High-Efficiency Small-Scale Combined Heat and Power Organic Binary Rankine Cycles

Directory of Open Access Journals (Sweden)

Costante Mario Invernizzi

2018-04-01

Full Text Available Small-CHP (Combined Heat and Power systems are generally considered a valuable technological option to the conventional boilers, in a technology developed context. If small-CHP systems are associated with the use of renewable energies (biomass, for example they could play an important role in distributed generation even in developing countries or, in any case, where there are no extensive electricity networks. Traditionally the considered heat engines for micro- or mini-CHP are: the gas engine, the gas turbine (with internal combustion, the steam engine, engine working according to the Stirling and to the Rankine cycles, the last with organic fluids. In principle, also fuel cells could be used. In this paper, we focus on small size Rankine cycles (10–15 k W with organic working fluids. The assumed heat source is hot combustion gases at high temperature (900–950 ∘ C and we assume to use only single stages axial turbines. The need to work at high temperatures, limits the choice of the right organic working fluids. The calculation results show the limitation in the performances of simple cycles and suggest the opportunity to resort to complex (binary cycle configurations to achieve high net conversion efficiencies (15–16%.

ASSESSMENT OF COMBINED HEAT AND POWER SYSTEM"PREMIUM POWER" APPLICATIONS IN CALIFORNIA

Energy Technology Data Exchange (ETDEWEB)

Norwood, Zack; Lipman, Timothy; Stadler, Michael; Marnay, Chris

2010-06-01

The effectiveness of combined heat and power (CHP) systems for power interruption intolerant,"premium power," facilities is the focus of this study. Through three real-world case studies and economic cost minimization modeling, the economic and environmental performance of"premium power" CHP is analyzed. The results of the analysis for a brewery, data center, and hospital lead to some interesting conclusions about CHP limited to the specific CHP technologies installed at those sites. Firstly, facilities with high heating loads prove to be the most appropriate for CHP installations from a purely economic standpoint. Secondly, waste heat driven thermal cooling systems are only economically attractive if the technology for these chillers can increase above the current best system efficiency. Thirdly, if the reliability of CHP systems proves to be as high as diesel generators they could replace these generators at little or no additional cost if the thermal to electric (relative) load of those facilities was already high enough to economically justify a CHP system. Lastly, in terms of greenhouse gas emissions, the modeled CHP systems provide some degree of decreased emissions, estimated at approximately 10percent for the hospital, the application with the highest relative thermal load in this case

Performance analysis of phase-change material storage unit for both heating and cooling of buildings

Science.gov (United States)

Waqas, Adeel; Ali, Majid; Ud Din, Zia

2017-04-01

Utilisation of solar energy and the night ambient (cool) temperatures are the passive ways of heating and cooling of buildings. Intermittent and time-dependent nature of these sources makes thermal energy storage vital for efficient and continuous operation of these heating and cooling techniques. Latent heat thermal energy storage by phase-change materials (PCMs) is preferred over other storage techniques due to its high-energy storage density and isothermal storage process. The current study was aimed to evaluate the performance of the air-based PCM storage unit utilising solar energy and cool ambient night temperatures for comfort heating and cooling of a building in dry-cold and dry-hot climates. The performance of the studied PCM storage unit was maximised when the melting point of the PCM was ∼29°C in summer and 21°C during winter season. The appropriate melting point was ∼27.5°C for all-the-year-round performance. At lower melting points than 27.5°C, declination in the cooling capacity of the storage unit was more profound as compared to the improvement in the heating capacity. Also, it was concluded that the melting point of the PCM that provided maximum cooling during summer season could be used for winter heating also but not vice versa.

Performance of a convective, infrared and combined infrared- convective heated conveyor-belt dryer.

Science.gov (United States)

El-Mesery, Hany S; Mwithiga, Gikuru

2015-05-01

A conveyor-belt dryer was developed using a combined infrared and hot air heating system that can be used in the drying of fruits and vegetables. The drying system having two chambers was fitted with infrared radiation heaters and through-flow hot air was provided from a convective heating system. The system was designed to operate under either infrared radiation and cold air (IR-CA) settings of 2000 W/m(2) with forced ambient air at 30 °C and air flow of 0.6 m/s or combined infrared and hot air convection (IR-HA) dryer setting with infrared intensity set at 2000 W/m(2) and hot at 60 °C being blown through the dryer at a velocity of 0.6 m/s or hot air convection (HA) at an air temperature of 60 °C and air flow velocity 0.6 m/s but without infrared heating. Apple slices dried under the different dryer settings were evaluated for quality and energy requirements. It was found that drying of apple (Golden Delicious) slices took place in the falling rate drying period and no constant rate period of drying was observed under any of the test conditions. The IR-HA setting was 57.5 and 39.1 % faster than IR-CA and HA setting, respectively. Specific energy consumption was lower and thermal efficiency was higher for the IR-HA setting when compared to both IR-CA and HA settings. The rehydration ratio, shrinkage and colour properties of apples dried under IR-HA conditions were better than for either IR-CA or HA.

1?10 kW Stationary Combined Heat and Power Systems Status and Technical Potential: Independent Review

Energy Technology Data Exchange (ETDEWEB)

Maru, H. C.; Singhal, S. C.; Stone, C.; Wheeler, D.

2010-11-01

This independent review examines the status and technical potential of 1-10 kW stationary combined heat and power fuel cell systems and analyzes the achievability of the DOE cost, efficiency, and durability targets for 2012, 2015, and 2020.

Web service discovery among large service pools utilising semantic similarity and clustering

Science.gov (United States)

Chen, Fuzan; Li, Minqiang; Wu, Harris; Xie, Lingli

2017-03-01

With the rapid development of electronic business, Web services have attracted much attention in recent years. Enterprises can combine individual Web services to provide new value-added services. An emerging challenge is the timely discovery of close matches to service requests among large service pools. In this study, we first define a new semantic similarity measure combining functional similarity and process similarity. We then present a service discovery mechanism that utilises the new semantic similarity measure for service matching. All the published Web services are pre-grouped into functional clusters prior to the matching process. For a user's service request, the discovery mechanism first identifies matching services clusters and then identifies the best matching Web services within these matching clusters. Experimental results show that the proposed semantic discovery mechanism performs better than a conventional lexical similarity-based mechanism.

Solar heat storages in district heating networks

Energy Technology Data Exchange (ETDEWEB)

Ellehauge, K. (Ellehauge og Kildemoes, AArhus (DK)); Engberg Pedersen, T. (COWI A/S, Kgs. Lyngby (DK))

2007-07-15

This report gives information on the work carried out and the results obtained in Denmark on storages for large solar heating plants in district heating networks. Especially in Denmark the share of district heating has increased to a large percentage. In 1981 around 33% of all dwellings in DK were connected to a district heating network, while the percentage in 2006 was about 60% (in total 1.5 mio. dwellings). In the report storage types for short term storage and long term storages are described. Short term storages are done as steel tanks and is well established technology widely used in district heating networks. Long term storages are experimental and used in connection with solar heating. A number of solar heating plants have been established with either short term or long term storages showing economy competitive with normal energy sources. Since, in the majority of the Danish district heating networks the heat is produced in co-generation plants, i.e. plants producing both electricity and heat for the network, special attention has been put on the use of solar energy in combination with co-generation. Part of this report describes that in the liberalized electricity market central solar heating plants can also be advantageous in combination with co-generation plants. (au)

Increased system benefit from cogeneration due to cooperation between district heating utility and industry

Energy Technology Data Exchange (ETDEWEB)

Danestig, M.; Henning, D. [Division of Energy Systems, Department of Mechanical Engineering, Linkoping Institute of Technology, Linkoping (Sweden)

2004-07-01

District heating and steam supply in the town Oernskoeldsvik in northern Sweden is in focus for this study. Low temperature waste heat from pulp manufacturing in the Donisjoe mill is now utilised for district heating production in heat pumps, which dominate district heating supply. Based on this traditional cooperation between the local district heating utility and the pulp industry, the parties discuss a partial outsourcing of the industrial steam supply to the utility, which may enable beneficial system solutions for both actors. The local utility must find a new location for a heating plant because a railway line is being built at the heat pump site. Planning for a new combined heat and power production (CHP) plant has started but its location is uncertain. If the plant can be situated close to the mill it can, besides district heating, produce steam, which can be supplied to adjacent industries. The municipality and its local utility are also considering investing in a waste incineration plant. But is waste incineration suitable for Ornskoeldsvik and how would it interact with cogeneration. Alternative cases have been evaluated with the MODEST energy system optimisation model, which minimises the cost for satisfying district heating and steam demand. The most profitable solution is to invest in a CHP plant and a waste incineration plant. Considering carbon dioxide emissions, the results from applying a local or a global perspective are remarkably different. In the latter case, generated electricity is assumed to replace power from coal condensing plants elsewhere in the North-European power grid. Therefore, minimum global CO{sub 2} emissions are achieved through maximal electricity production in a CHP plant. From this viewpoint, waste incineration should not be introduced because it would obstruct cogeneration. The study is carried out within the program Sustainable municipality run by the Swedish Energy Agency. (orig.)

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African Journals Online (AJOL)

Although contraceptives, including emergency contraceptives, are widely available free at public health facilities in South Africa, rates of teenage and unintended pregnancy are high. This paper analyses awareness and utilisation of emergency contraception amongst 193 young women (aged 15-24 years) attending public ...

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International Nuclear Information System (INIS)

Ullah Khan, Imran; Hafiz Dzarfan Othman, Mohd; Hashim, Haslenda; Matsuura, Takeshi; Ismail, A.F.; Rezaei-DashtArzhandi, M.; Wan Azelee, I.

2017-01-01