Reactor. Analysis. Methods ............................. Reactor. Design and Critical. Experiments ... Lateral support .................................. Vibration ..................................... FLUID. SYSTEMS .... tube. The removal of heat is provided by pumping the water through the .... a water flow loop and a heat exchanger .... into six shell-and-tube ...

The shell and tube heat exchangers were introduced to apply to a big capacity condenser and a high pressure feed water heater for power plant in the beginning of 1990s. Design and manufacturing technology for shell and tube heat exchangers have been developed until now. But it is very difficult to calculate the expected performance characteristics of the shell and tube heat exchanger, because there are many design parameters to be considered according to internal structure and the shell side heat transfer mechanism complicately related to the design parameters. Design parameters to be considered in the design stage of shell and tube heat exchanger are shell and tube side fluids, flow rate, inlet and outlet temperature, physical properties, type of heat exchanger, outer diameter, thickness, length of tube, tube arrangement, tube pitch, permissive pressure loss on both sides, type of baffle plate, baffle cutting ratio. The propose of study is an analysis TEMA(Tubular Exchanger Manufacturers Association) E shell and tube heat exchanger performance with changing a number of baffles(3, 5, 7, 9, 11) and tubes(16, 20) and determined optimal baffle spacing. (author). 11 refs., 12 figs., 2 tabs.

In this paper, the new approach of constructal theory has been employed to design shell and tube heat exchangers. Constructal theory is a new method for optimal design in engineering applications. The purpose of this paper is optimization of shell and tube heat exchangers by reduction of total cost of the exchanger using the constructal theory. The total cost of the heat exchanger is the sum of operational costs and capital costs. The overall heat transfer coefficient of the shell and tube heat exchanger is increased by the use of constructal theory. Therefore, the capital cost required for making the heat transfer surface is reduced. Moreover, the operational energy costs involving pumping in order to overcome frictional pressure loss are minimized in this method. Genetic algorithm is use...

Shell and tube heat exchanger with single twisted tube bundle in five different twist angles, are studied using computational fluid dynamics (CFD) and compared to the conventional shell and tube heat exchanger with single segmental baffles. Effect of shell-side nozzles configurations on heat exchanger performance is studied as well. Heat transfer rate and pressure drop are the main issues investigated in the paper. The results show that, for the same shell-side flow rate, the heat transfer coefficient of heat exchanger with twisted tube bundle is lower than that of the heat exchanger with segmental baffles while shell-side pressure drop of the former is even much lower than that of the latter. The comparison of heat transfer rate per unit pressure drop versus shell-side mass flow rate show...

Shell-and-tube heat exchangers are normally designed on the basis of a uniform and constant fouling resistance that is specified in advance by the exchanger user. The design process is then one of determining the best exchanger that will achieve the thermal duty within the specified pressure drop constraints. It has been shown in previous papers [Designing shell-and-tube heat exchangers with velocity-dependant fouling, 34th US national Heat Transfer Conference, 20-22 August 2000, Pittsburg, PA; Designing shell-and-tube heat exchangers with velocity-dependant fouling, 2nd Int. Conf. on Petroleum and Gas Phase Behavior and Fouling, 27-31 August 2000, Copenhagen] that this approach can be extended to the design of exchangers where the design fouling resistance depends on velocity. The current paper briefly reviews the main findings of the previous papers and goes on to treat the case where the fouling depends also on the local temperatures. The Ebert-Panchal [Analysis of Exxon crude-oil, slip-stream coking data, Engineering Foundation Conference on Fouling Mitigation of Heat Exchangers, 18-23 June 1995, California] form of fouling rate equation is used to evaluate this fouling dependence. When allowing for temperature effects, it becomes difficult to divorce the design from the way the exchanger will be operated up to the point when the design fouling is achieved. However, rational ways of separating the design from the operation are proposed. (author)

This thesis consists of two parts. Part 1: Experimental and numerical study of jetfire stop, and Part 2: Experimental and numerical study of a new kind of shell and tube heat exchanger with helical flow on shell side. Part 1 describes the development of the model for simulation of the temperature development through Viking jetfirestop. A simulation program is developed that calculates the temperature development through Viking jetfire stop. In the development of the model, measurements of reaction energy, pyrolysis and heat conductivity at low temperatures are made. The conductivity at higher temperatures and when pyrolysis reactions are going on is estimated experimentally and by numerical calculations. Full-scale jet fire test and small-scale xenon lamp experiments are made to test the simulation model. Part 2 contains the development of a model that simulate the fluid flow and heat transfer in a helical flow shell and tube heat exchanger. It consists of the development of a porosity model and a model for pressure drop and heat transfer as well as experiments in non-standard tube layouts. Results from the simulation program are compared with experiments on a helical flow shell and tube heat exchanger. There is a separate appendix volume. 62 refs., 152 figs., 22 tabs.

A high temperature design and evaluation of creep-fatigue damage for a sodium-to-air heat exchanger, AHX, has been conducted according to the recent versions of the high temperature design codes based on a full three-dimensional finite element analysis. AHX is a shell- and tube-type heat exchanger with 36 helical tubes, and has an outer diameter of 1.59m and height of 6.5m. AHX was installed in a sodium test loop facility, STELLA (Sodium integral effect test loop for safety simulation and assessment) recently constructed at the KAERI site. The materials of the shell and tube in AHX are 304SS and 316SS, respectively. Evaluations of creep-fatigue damage based on 3D finite element analyses were conducted at several critical locations of AHX according to the recent elevated temperature design ...

This article presents the results of the application of a quite simple method for analyzing shell-side fouling in shell-and-tube exchangers, capable of taking into account the formation or irregular fouling deposits with variable thermal conductivity. This method, based on the utilization of elementary heat exchangers, has been implemented for E-shell TEMA-type heat exchangers with two tube passes. Several fouling deposit distributions have been simulated so as to ascertain their effects on the heat transfer rate. These distributions consider that fouling is concentrated in zones where the temperature of the fluids is maximum or minimum.

Heat transfer for boiling and condensing carbon dioxide has been investigated.Heat transfer for carbon dioxide evaporating inside pipe has been measured and compared with Shah's correlation. The measured heat transfer coefficient is much higher than the value determined with the correlation.A shell-and-tube heat exchanger with carbon dioxide on the shell side and flow ice inside the tubes has been used to investigate the heat transfer for condensing carbon dioxide.At leats is mentioned results obtained with a frozen food display case using carbone dioxide as refrigerant.

In this work the effect that is produced considering the local value of the thermo-physical properties of the fluids, on the convective coefficients in shell-and-tube heat exchangers, was determined. In order to obtain the temperature distribution, the exchanger was discretized in elements, which allowed to compute the thermo-physical properties and the local convective coefficients, on the shell side and on the tubes side as well. With these results mean convective coefficients were evaluated and compared with those obtained by the logarithmic-mean-temperature-difference method, obtaining a difference less than two percent which does not affect the final result of the exchanger. (author)

The primary coolant systems for the heavy-water nuclear materials production reactors at the Savannah River Site are coupled to the secondary coolant systems through shell and tube heat exchangers. The head, shell, and tube sheets of these heat exchangers are fabricated from AISI Type 304 grades of austenitic stainless steel. The 8,957 tubes in each heat exchanger were originally fabricated from Type 304 stainless steel, but service experience has lead to the use of Sea Cure tubing in newer systems. The design includes double tube sheets, core rods, and 33,410 square feet of heat transfer surface. Tubes are rolled into the tube sheets and seal welded after rolling. The tubes contain Type 304 stainless steel rods which are positioned in the center of each tube axis to increase the fraction of the cooling water contacting the heat transfer surface. Each reactor utilizes twelve heat exchangers; thus the 120+ reactor-years of operating experience provide approximately 1,440 heat exchanger-years of service. Fatigue, stress corrosion cracking, crevice corrosion, and pitting have been observed during the service life. This paper describes the observed degradation processes and uses the operational experience to recommend materials for the Heavy Water -- New Production Reactor (HW-NPR).

Most geothermal fluids, because of their elevated temperature, contain a variety of dissolved chemicals. These chemicals are frequently corrosive toward standard materials of construction. As a result, it is advisable in most cases to isolate the geothermal fluid from the process to which heat is being transferred. The task of heat transfer from the geothermal fluid to a closed process loop is most often handled by a plate heat exchanger. The two most common types used in geothermal applications are: bolted and brazed. For smaller systems, in geothermal resource areas of a specific character, downhole heat exchangers (DHEs) provide a unique means of heat extraction. These devices eliminate the requirement for physical removal of fluid from the well. For this reason, DHE-based systems avoid entirely the environmental and practical problems associated with fluid disposal. Shell and tube heat exchangers play only a minor role in low-temperature, direct-use systems. These units have been in common use in industrial applications for many years and, as a result, are well understood. For these reasons, shell and tube heat exchangers will not be covered in this chapter.

This study presents a new design, and thermodynamic and engineering analyses of the H[sub 2]SO[sub 4] decomposition section of the sulphur-iodine thermochemical cycle for producing hydrogen. Excess oxygen is used as an energy vector in various direct contact adiabatic equipment and shell and tube heat exchangers are eliminated as much as possible. Thermodynamic (energy and exergy) and cost analyses have been carried out. The results show that energetic and exergetic efficiencies are 64.2% and 64.0% respectively and typical cost is 3.3$(1990) per kmol SO[sub 2] for 4$US(1990)/GJ nuclear heat cost. (author)

This paper addresses the thermodynamics of heat storage in a PCM shell-and-tube heat exchanger, which in a solar power plant is provided to damp the pulsed behaviour of the heat source. Unequal duration of the active and passive phases of the heat source, and consequently of the heat storage and discharge, is allowed. Two alternative schemes of connection of the storage element to the heat engine, referred to as the series and the parallel set-ups, are considered. Using the general framework developed in our previous work, we reformulate the second-law efficiencies for each scheme in terms of a few dimensionless parameters, reflecting the operating conditions of the system and the relevant heat-transfer characteristics of the storage element. For the particular storage system studied in this paper, i.e. the PCM shell-and-tube heat exchanger executing periodic storage-removal cycles, the latter characteristics are determined numerically. A parametric study is conducted to compare the series and parallel schemes with regard to various design objectives. 23 refs., 15 figs., 1 tab.

Design guidelines were developed to prevent tube failures due to excessive flow-induced vibration in shell-and-tube heat exchangers. An overview of vibration analysis procedures and recommended design guidelines is presented in this paper. This paper pertains to liquid, gas and two-phase heat exchangers such as nuclear steam generators, reboilers, coolers, service water heat exchangers, condensers, and moisture-separator-reheaters. Generally, a heat exchanger vibration analysis consists of the following steps: (i) flow distribution calculations, (ii) dynamic parameter evaluation (i.e. damping, effective tube mass, and dynamic stiffness), (iii) formulation of vibration excitation mechanisms, (iv) vibration response prediction, and (v) resulting damage assessment (i.e., comparison against allowables). The requirements applicable to each step are outlined in this paper. Part 1 of this paper covers flow calculations, dynamic parameters and fluidelastic instability.

Ammonia is the most cost-effective working fluid for many Rankine power cycles and is widely utilized in industrial refrigeration applications. For example, it was selected as the most advantageous working fluid for the comprehensive closed-cycle Ocean Thermal Energy Conversion investigations where the heat source and sink are the warm, surface seawater and the cold, deep seawater, respectively. An essential part of this investigation was to measure the performance of many advanced heat-exchanger types using ammonia as the working fluid and to compare these results with those for conventional shell-and-tube designs. This paper presents an overview of these experiments and their potential significance for improved energy efficiency for industrial refrigeration applications. The heat exchangers used for industrial refrigeration systems account for about 50% of the equipment cost. However, current practice is to use state-of-the-art designs -- the shell-and-tube type without enhanced tubes. Substantial energy savings are possible through the use of advanced ammonia evaporator and condenser heat-exchanger types. 31 refs., 10 figs., 6 tabs.

A sodium-to-sodium heat exchanger has been widely used in a sodium-cooled fast reactor as an intermediate heat exchanger (IHX) or a decay heat exchanger (DHX). It is basically a shell-and-tube type counter-current flow heat exchanger, and sodium flows along the tube bundles on the shell-side of the heat exchanger. An accurate prediction of a heat transfer performance is very important for the heat exchanger thermal sizing in a sodium-cooled fast reactor (SFR) design application. To this end, a proper heat transfer coefficient for the appropriate design conditions should be provided for a better design of sodium heat exchangers. However, the experimental correlations for a heat transfer of liquid metal are very rare in the literature and they have large uncertainties since the experiment is very expensive and difficult. The most difficult thing is that the differences among the correlations are so serious that it is difficult to decide which correlation should be used for a particular flow situation. In the present study, we surveyed the conventional heat transfer correlations for single-phase liquid metal flows in a heat exchanger design. The thermal sizing results of sodium heat exchangers with respect to the Nusselt (Nu) number correlations were quantitatively discussed

The presence of a rising bubble in a fluid can greatly enhance heat transfer from adjacent heated surfaces such as in shell and tube heat exchangers and chemical reactors. One specific case of this is when a bubble impacts and slides along the surface. The result is heat transfer enhancement by two main mechanisms: first, the bubble itself acting as a bluff body, and second, the wake generated behind the bubble leads to increasing mixing. The current research is concerned with measuring the heat transfer from a submerged heated surface that is subject to a sliding bubble flow. An ohmically heated 25mm thick stainless steel foil, submerged in a water tank, forms the test surface. An air bubble is injected onto the lower surface of the test plate, it slides along its length and the effects a...

Rotary steam tube dryer is an indirect heat type dryer, and is very similar to rotating shell and tube heat exchanger. Wet solid particles are heated by steam through heating tubes and dried by blowing off the vapour with the carrier gas. The drying phenomenon is complicated. If the drying performance could be analyzed theoretically from operating conditions, using a model which simplifies the phenomena inside the dryer, then correlations among the parameters could be estimated. This paper describes a simplified model and estimation method of the dryer. From the analytical model; longitudinal profile of carrier gas temperature, solid temperature, absolute humidity of carrier gas and liquid content of solid particle were obtained, and then drying mechanism and correlation between some parameters were determined. Furthermore, calculated values by the model roughly agreed with actual operation data as overall heat transfer coefficients. This method is very useful for designing and scaling up the dryer. 6 refs., 8 figs., 1 photo.

Refering to the results of our previous works, a procedure for estimating the distribution of heat flux in shell-and-tube heat exchangers is proposed. The steam generator used in a high temperature reactor plant is taken up as the subject of analysis. Particular attention is paid to critical conditions for burnout and the strength of material in high temperature conditions. It is found that the distribution of heat transfer coefficient on the shell-side is crucial to the occurrence of burnout in the tubes. The use of a relatively large inlet nozzle (the ratio of its diameter to the shell is roughly half) is recommended. A low level of thermal stress on heat transfer tubes can be realized by the adoption of a relatively thin 2.25 Cr-1 Mo Steel tube wall of 1.24 mm thickness.

This report presents the results of an effort to develop and design a unique thermoplastic film heat exchanger for use in an industrial heat pump evaporator system and other energy recovery applications. The concept for the exchanger is that of individual heat exchange elements formed by two adjoining and freely hanging plastic films. Liquid flows downward in a regulated fashion between the films due to the balance of hydrostatic and frictional forces. The fluid stream on the outside of film may be a free-falling liquid film, a condensing gas, or a noncondensing gas. The flow and structural principles are similar to those embodied in an earlier heat exchange system developed for use in waste water treatment systems (Sanderson). The design allows for high heat transfer rates while working within the thermal and structural limitations of thermoplastic materials. The potential of this new heat exchanger design lies in the relatively low cost of plastic film and the high inherent corrosion and fouling resistance. This report addresses the selection of materials, the potential heat transf er performance, the mechanical design and operation of a unit applied in a low pressure steam recovery system, and the expected selling price in comparison to conventional metallic shell and tube heat exchangers.

Analysis of field performance data from a binary cycle test loop using geothermal brine and a hydrocarbon working fluid is reported. Results include test loop operational problems, and shell-and-tube heat exchanger performance factors such as overall heat transfer coefficients, film coefficients, pinch points, and pressure drops. Performance factors are for six primary heaters having brine in the tubes and hydrocarbon in the shells in counterflow, and for a condenser having cooling water in the tubes and hydrocarbon in the shell. Working fluids reported are isobutane, 90/10 isobutane/isopentane, and 80/20 isobutane/isopentane. Performance factors are for heating each working fluid at supercritical conditions in the vicinity of their critical pressure and temperature and condensing the same fluid.

This paper presents a numerical simulation of the fluid flow and heat transfer in the shell-side of a large-scale shell-and-tube heat exchanger with longitudinal flow through porous-medium and distributed-resistance model. Such characteristics as flow field distribution, shell-side pressure drop, heat transfer performance and overall performance factor of the shell-side were studied with change in L/D and Re. It was shown that when L/D decreased from 6.0 to 1.5 with the same Re, the fluid flow maldistribution became intense, pressure drop increased sharply, and that the overall performance factor ? decreased sharply. Particularly, when L/D? 2.0, the problems became more and more serious. Through a detailed analysis of the pressure field distribution, it was discovered that &#...

A concept for an artificial upwelling driven by salinity differences in the ocean to supply nutrients to a mariculture farm is described and analyzed. A long shell-and-tube counterflow heat exchanger built of inexpensive plastic and concrete is suspended vertically in the ocean. Cold, nutrient rich, but relatively fresh water from deep in the ocean flows up the shell side of the heat exchanger, and warm but relatively saline water from the surface flows down the tube side. The two flows exchange heat across the thin plastic walls of the tubes, maintaining a constant temperature difference along the heat exchanger. The plastic tubes are protected by the concrete outer shell of the heat exchanger. The flow is maintained by the difference in density between the deep and surface water due to their difference in salinity. This phenomenon was first recognized by the oceanographer Stommel, who termed it The Perpetual Salt Fountain. The heat transfer and flow rate as a function of tube number and diameter is analyzed and the size of the heat exchanger optimized for cost is determined for a given flow of nutrients for various locations. Reasonable sizes (outer diameter on the order of 5 m) are obtained. The incremental capital cost of the salinity-driven artificial upwelling is compared to the incremental capital cost and present value of the operating cost of an artificial upwell fueled by liquid hydrocarbons.

Solar energy is an intermittent supply source of energy. To efficiently utilize this free renewable energy source some form of thermal energy storage devices are necessary. Phase change materials (PCMs), because of their high energy density storage capacity and near isothermal phase change characteristics, have proven to be promising candidates for latent heat thermal energy storage (LHTES) devices. Among the various LHTES devices for low temperature residential heating and cooling applications, the shell-and-tube type heat exchanging devices are the most simple to operate and can be easily fabricated. This work numerically investigates the buoyancy driven heat transfer process during melting (charging) of a commercial paraffin wax as PCM filling the annulus of a horizontal double pipe heat exchanger. The heated working fluid (water) is passing through the central tube of the annulus at a sufficiently high flow-rate and thereby maintaining an almost isothermal wall temperature at the inner pipe which is higher than the melting temperature of the PCM. The transient, two-dimensional coupled laminar momentum and energy equations for the model are suitably non-dimensionalized and are solved numerically using the enthalpy-porosity approach. Time-wise evolutions of the flow patterns and temperature distributions are presented through velocity vector fields and isotherm plots. In this study, two types of PCM filled annuli, a plain annulus and a strategically placed longitudinal finned annulus, are studied. The total energy stored, the total liquid fraction and the energy efficiency at different melting times are evaluated for three different operating conditions and the results are compared between the plain and finned annuli. The present study will provide guidelines for system thermal performance and design optimization of the shell-and-tube LHTES devices. .

Laboratory and operational studies of heat transfer (HT) are presented. Such topics as the irreversibility of HT and mass transfer (MT), HT in disperse systems at high temperatures, fixed-bed reactors with submerged tube bundles, HT and MT in a low-speed turbulent boundary layer with condensation, multilayer insulation blankets for spacecraft applications, HT and MT in transpiration-cooled turbine blades, and finite-element analysis of HT in a solid with radiation and ablation are discussed. Contributions are included on the design of shell-and-tube heat exchangers to avoid flow-induced vibration, HT and MT in air-conditioning cooling coils, a friction-factor correlation for the offset strip-fin matrix, convective HT in gas-turbine combustion chambers, thermal-energy storage systems, turbulent buoyant HT in enclosures containing fire sources, a phase-change dry/wet cooling system for power plants, and the effect of secondary flow on HT in solar collector tubes. For individual items see A83-43014 to A83-43024

The availability of computational methods to simulate fluid flow in the complex, three-dimensional geometry of heat exchangers recently prompted the development of a Heat Exchanger Vibration Analysis (HXVA) method that accounts for nonuniform flow velocity distributions in the determination of fluidelastic tube bundle instabilities. The concurrent acquisition of flow-induced vibration (FIV) test data for several configurations of an industrial-size shell-and-tube heat exchanger made possible this evaluation of the HXVA method for six cases. The ability to predict the overall heat exchanger pressure drop with the hydrodynamic code COMMIX-IHX was good. Another useful capability of the HXVA method is the ability to predict the general location of the tubes most susceptible to FIV instabilities, in particular, those tubes located along the baffle cut in the baffle flow windows. However, finer discrimination of susceptibility between the tubes along the baffle cut was not possible and is believed to be beyond the current state-of-the-art. Also, global prediction of critical flowrates was better than local predictions. The predicted lowest critical flowrate (for safe heat exchanger operation) was less than 20% too large in four of the six cases and less than 50% too large in the other two cases. However, errors in predicting the critical flowrates of individual tubes were as large as 100%. Recommendations to improve the prediction capability were made, with priority on the excitation mechanism for dense fluid flows with nonuniform velocity distributions.

The design and construction of the new Branched GAX prototype is in progress. The new design is based on the lessons learned during the operation of the first Branched GAX prototype and also a basic GAX prototype. The first Branched GAX prototype was built before the initiation of this project, with standard off-the-shelf components and shell and tube heat exchanger design. The performance of the prototype was well below the theoretical limits. Alternate component designs were tested as part of a parallel project on a 5 refrigeration ton basic GAX prototype. The lessons of those two prototypes are directly applicable to the Branched GAX project and are being incorporated into the current design. To facilitate design and construction and to provide a common reference point for comparison with the basic GAX prototype, the new Branched GAX prototype is being designed for a 5 refrigeration ton capacity. The design effort is now nearing completion, and component construction is underway.

A major prerequisite for analyzing the fluid elastic vibration of tube bundles of shell-and-tube heat exchangers is a detailed knowledge of the thermal-hydraulic conditions of secondary side flow and the density of primary fluid. This paper presents the results of secondary side flow calculations for four different tube plugging situations in a pressurized water reactor ( PWR ) recirculating type steam generator as one part of the fluid elastic vibration analysis of the steam generator U-tubes. The analysis has been performed by employing the ATHOS3 two-phase flow code. Typical results have been provided for the plane distributions of velocity and void fraction of the secondary fluid, and for the distributed cross-flow gap velocity and density of the secondary fluid along the length of U-tube.

Fouling plays a dominant role in heat exchanger performance. It is extremely important to choose the most appropriate type of heat exchanger for a particular application and adopt proper values for fouling resistance. A design practice for shell-and-tube heat exchangers that will limit fouling to a minimum and thus ensure trouble-free operation is essential. Due to the availability of specialized software, the thermal design of heat exchangers has become precise and scientific. The results occasionally have to be tempered with practical experience and engineering judgment, but generally these computer programs are very reliable and authentic. However, the above is true only for determining heat-transfer coefficients and pressure drop. One important area that cannot possibly be addressed by design software is fouling. While a proper selection of fouling resistance is extremely difficult due to the numerous factors involved, a sound design practice will minimize any errors. However, it is important to first understand the phenomenon of fouling. The paper describes what fouling is, types of fouling, factors affecting fouling, providing a fouling allowance, selecting a fouling resistance, and overcoming fouling through better design.

This work aims at the optimization of the heat transfer of refrigerant R134a on finned tubes in shell-and-tube condensers. The coating and optimization of the fin structure should increase the drainage of the condensate in the space between the fins and therefore the condensation heat transfer on single tubes and tube bundles. (orig.)

This study focused on natural convection heat transfer using a vertical rectangular sub-channel and water as the coolant fluid. To conduct this study has been made pipe heaters are equipped with thermocouples. Each heater is equipped with five thermocouples along the heating pipes. The diameter of each heater is 2.54 cm and 45 cm in length. The distance between the central heating and the pitch is 29.5 cm. Test equipment is equipped with a primary cooling system, a secondary cooling system and a heat exchanger. The purpose of this study is to obtain new empirical correlations equations of the vertical rectangular sub-channel, especially for the natural convection heat transfer within a bundle of vertical cylinders rectangular arrangement sub-channels. The empirical correlation equation can support the thermo-hydraulic analysis of research nuclear reactors that utilize cylindrical fuel rods, and also can be used in designing of baffle-free vertical shell and tube heat exchangers. The results of this study that the empirical correlation equations of natural convection heat transfer coefficients with rectangular arrangement is Nu = 6.3357 (Ra.Dh/x)0.0740.

A study was conducted to examine the use of aluminum-oxygen fuel cells to keep divers warm during undersea dives. This report describes the second phase of a program to develop the Diver Heating System (DHS). The first phase involved an aluminum-oxygen fuel cell which was only 50 per cent efficient and which required a heat exchanger to recover the rejected heat to the electrolyte. The second phase of the program involved the development of a pumped system which had cost and logistical advantages over a stacked fuel cell. The pumped system was designed, built and successfully tested underwater and delivered 500 Watts of thermal output for a period of 5.5 hours. The test showed the integration of all 3 subsystems of the fuel cell, but did not include integration of the fuel cell with the DHS developed by Delta Temax. The pumped system design required a completely new cell stack design, and a shell-and-tube heat exchanger to remove heat from the electrolyte as it was pumped through the cell stack. It also required the design of an oxygen supply regulator, a pump enclosure that was housed in the electrolyte sump, and integration of all these systems inside an insulated enclosure for underwater testing. The development of the subsystems that make up the fuel cell were outlined with reference to the cell stack, thermal management, oxygen supply, electrolyte sump, electrolyte pump, hydrogen removal, buoyancy compensation, insulation, packaging and electrical components. 1 tab., 15 figs.

Design of the long district heating system to Belgrade (base load 580 MJ/s) from Thermal Power Station `Nikola Tesla A`, 30 km southwest from the present gas/oil burning boilers in New Belgrade, is being conducted. The mathematical model and computer code named TRP are developed for the prediction of the design basis parameters of heat exchangers station, as well as for selection of protection devices and formulation of operating procedures. Numerical simulations of heat exchangers station are performed for various transient conditions: up-set and abnormal. Physical model of multi-pass, shell and tube heat exchanger in the station represented is by unique steam volume, and with space discretised nodes both for water volume and tube walls. Heat transfer regimes on steam and water side, as well as hydraulic calculation were performed in accordance with TEMA standards for transient conditions on both sides, and for each node on water side. Mathematical model is based on balance equations: mass and energy for lumped parameters on steam side, and energy balances for tube walls and water in each node. Water mass balance is taken as boundary/initial condition or as specified control function. The physical model is proposed for (s) heat exchangers in the station and (n) water and wall volumes. Therefore, the mathematical model consists of 2ns+2, non-linear differential equations, including equations of state for water, steam and tube material, and constitutive equations for heat transfer on steam and water side, solved by the Runge-Kutt method. Five scenarios of heat exchangers station behavior have been simulated with the TRP code and obtained results are presented. (author)

Solar thermal energy storage systems can be categorized based on materials that store either as sensible heat or as latent heat of fusion. For convenience, the latter are designated as phase change materials (PCM). It is a fairly well accepted fact that PCM storage devices usually require less storage volume. In a recent paper, heat exchanger effectiveness for PCM storage units was theoretically derived and presented in chart form. The heat exchanger considered was a shell-and-tube type, viz., the shell side filled with PCM and the tube side with heating or cooling fluid. The PCM heat storage system presented here, however, involves both heating and cooling fluids with a PCM in the middle composed of rectangular channels. This system may be used to store the thermal energy absorbed by a solar collector for the purpose of heating a building. The thermal energy carried by a hot fluid coming from the solar collector can be transferred through the upper surface I. The thermal energy stored in the system can be extracted through the lower surface II by a cold fluid circulating through the building. In order to transfer heat to the melting PCM, the temperature of the hot fluid must be higher than the melting point of the PCM, T /SUB m/ , and to remove heat from the solidifying PCM, the temperature of the cold fluid must be lower than T /SUB m/ . Therefore, the melting point of the PCM presents a limitation of the temperature of both the hot and cold fluids. This temperature limitation is more or less similar to the temperature restriction of a parallel-flow heat exchanger, in which the final temperature of the cold fluid can never reach the outlet temperature of the hot fluid.

The purpose of this investigation was to develop a procurement specification for recuperative heat exchangers in Compressed Air Energy Storage Applications. Potential problem areas were identified and designs, operational guidelines, and a procurement specification were developed to minimize these problems. Interviews were conducted at existing recuperative gas turbine installations to identify the existing experience with recuperators. Thermal stress cracking, low temperature sulfuric acid corrosion, and structural vibrations were identified as the most common problems. A literature search was conducted to identify means to minimize the corrosion and vibrations. A finite element analysis of a tube to tubesheet joint for a shell-and-tube recuperator was performed to identify the impact of tubesheet thickness, weld types, materials, temperatures, construction details, and heat transfer coefficients on transient thermal stresses. From this analysis means to obtain acceptable cyclic life were identified. The results of this investigation indicate that a recuperator for a CAES plant can be designed and built at reasonable cost that will provide acceptable service life. The best life attained was estimated from analytic study to be thirty years. Ferritic steels provided longer life than austenitic due to both decreased corrosion rate and thermal stress. Design procedure, according to ASME Section VIII, Division 2 was recommended since more economical design for cyclic duty is possible. Vibration analysis was recommended for all recuperator final designs. Finally, a procurement specification was developed to enable both the purchaser and manufacturer to incorporate into a CAES plant a successfully operating and long-lived recuperative heat exchanger.

Heat exchanger test results for the first deployment of OTEC-1 are reported. These tests were aimed at evaluating the performance of a state-of-the-art 1 MWe, titanium shell-and-tube evaporator and condenser in an ocean environment. The evaporator was unique in that it consisted of both a plain and an enhanced tube bundle, whereas the condenser had plain tubes only. All tests with the evaporator were conducted in the sprayed-bundle mode. Experimental results for the condenser and plain-tube portion of the evaporator were found to be in excellent agreement with performance predictions. This result is important because it demonstrates that the thermal performance of large plain-tube heat exchangers can be predicted with a high level of confidence. On the other hand, performance of the enhanced-tube portion of the evaporator was much lower than predicted. Evidence strongly suggested that this poor performance was attributable mainly to fouling of the High Flux surface by corrosion products consisting predominantly of hydrated aluminum oxides.

Tube vibration data from tests of a specially built and instrumented, industrial-type, shell-and-tube heat exchanger are reported. The heat exchanger is nominally 0.6 m (2 ft) in dia and 3.7 m (12 ft) long. Both full tube and no-tubes-in-window bundles were tested for inlet/outlet nozzles of different sizes and with the tubes supported by seven, equally-spaced, single-segmental baffles. Prior to water flow testing, natural frequencies and damping of representative tubes were measured in air and water. Flow testing was accomplished by increasing the flow rates in stepwise fashion and also by sweeping through a selected range of flow rates. The primary variables measured and reported are tube accelerations and/or displacements and pressure drop through the bundle. Tests of the full tube bundle configuration revealed tube rattling to occur at intermediate flow rates, and fluidelastic instability, with resultant tube impacting, to occur when the flow rate exceeded a threshold level; principally, the four-span tubes were involved in the regions immediately adjacent to the baffle cut. For the range of flow rates tested, fluidelastic instability was not achieved in the no-tubes-in-window bundle; in this configuration the tubes are supported by all seven baffles and are, therefore, stiffer.

This report describes in detail all tests planned for the first eight-month deployment of OTEC-1, a test facility constructed by the US Department of Energy in order to test heat exchangers for closed-cycle power plants using ocean thermal energy. Tests to be performed during the first-deployment period are aimed primarily at determining (1) the effectiveness of countermeasures in preventing biofouling of the heat exchanters, (2) the extent of environmental impacts associated with operation of an OTEC facility, and (3) the performance of a 1-MWe, titanium shell-and-tube evaporator and condenser pair. The condenser to be tested has plain tubes, and the evaporator employs the Linde High Flux surface on the working-fluid (ammonia) side to enhance the heat-transfer rate. This plan provides a statement of the objectives and priorities of the test program, describes the test equipment, gives a detailed account of all tests to be performed and the test schedule, and discusses provisions for management of the test program.

The COMMIX-PPC computer pregrain is an extended and improved version of earlier COMMIX codes and is specifically designed for evaluating the thermal performance of power plant condensers. The COMMIX codes are general-purpose computer programs for the analysis of fluid flow and heat transfer in complex Industrial systems. In COMMIX-PPC, two major features have been added to previously published COMMIX codes. One feature is the incorporation of one-dimensional equations of conservation of mass, momentum, and energy on the tube stile and the proper accounting for the thermal interaction between shell and tube side through the porous-medium approach. The other added feature is the extension of the three-dimensional conservation equations for shell-side flow to treat the flow of a multicomponent medium. COMMIX-PPC is designed to perform steady-state and transient. Three-dimensional analysis of fluid flow with heat transfer tn a power plant condenser. However, the code is designed in a generalized fashion so that, with some modification, it can be used to analyze processes in any heat exchanger or other single-phase engineering applications. Volume I (Equations and Numerics) of this report describes in detail the basic equations, formulation, solution procedures, and models for a phenomena. Volume II (User`s Guide and Manual) contains the input instruction, flow charts, sample problems, and descriptions of available options and boundary conditions.

A comprehensive research program is being conducted to develop the necessary criteria to assist designers and operators of shell-and-tube heat exchangers to avoid detrimental flow-induced tube vibration. This paper presents an overview of the insights gained from shellside water-flow testing on a horizontal, industrial-sized test exchanger that can be configured in many ways using interchangeable tube bundles and replaceable nozzles. Nearly 50 different configurations have been tested representing various combinations of triangular, square, rotated-triangular, and rotated-square tubefield layouts; odd and even numbers of crosspasses; and both single- and double-segmental baffles with different cut sizes and orientations. The results are generally consistent with analytical relationships that predict tube vibration response by the combined reinforcing effect of the vibration mode shape and flow velocity distribution. An understanding of the vibration and instability performance is facilitated by recognizing that the excitation is induced by three separate, though sometimes interacting, flow conditions. These are the crossflows that generate ''classic'' fluidelastic instabilities in the interior of the tube bundle, the entrance and exit bundle flow from and into the shell nozzles, and the localized high velocity bypass and leakage stream flows. The implications to design and/or possible field remedies to avoid vibration problems are discussed. 17 refs., 10 figs.

The utilization of high calorie town gas with LNG is proceeded recently but because there are some technical and economical problems such as transportation and storage, the technical development was carried out with methanol which is liquid at room temperature. Multi-stage reactions were required to get methan rich gas from methanol but in this process, the conversion could be made by the monostage reaction, and further the fuel to heat raw material could be eliminated by elevating the thermal efficiency, using a shell and tube heat exchanger. The reaction is made at 9kg/cm/sup 2/G and 280/sup 0/C by using newly developed, highly active methanization catalyst. The pilot plant of gas production capacity of 10,000m/sup 3/N/d was designed, constructed and operated. As the result, it was verified from this plant that the reaction system, refining system and calorie regulating system were all stable; that the starting and emergency shutdown could be operated surely, that noise and smoke were fewer and that efficiency and economy were excellent. (10 figs, 5 tabs, 1 photo)

Abstract in spanish Se han utilizado los aproximantes de Padé para correlacionar algunas propiedades necesarias para el diseño y modelado de intercambiadores de calor de tubo y coraza usados en procesos de elaboración de aceites vegetales y sebo vacuno y en la producción de biodiesel, entre otras aplicaciones. Los aproximantes de Padé son funciones racionales que tienen la capacidad de representar funciones complejas con un número reducido de parámetros. Se ha considerado la densidad, (more) el calor específico, la viscosidad y la conductividad térmica de estas sustancias y se han determinado los parámetros del modelo estudiado usando datos experimentales de estas propiedades. El modelo de Padé usado muestra ser adecuado para el cálculo de las propiedades estudiadas obteniendo desviaciones similares o inferiores a otros modelos altamente no lineales. Abstract in english Padé approximants have been used to correlate some properties needed in the modeling and design of shell and tube heat exchangers used in the production of vegetables oils, beef tallow and biodiesel. Padé approximants are rational functions that have the capacity of representing complex functions with a reduce number of parameters. The properties considered were density, specific heat, viscosity and thermal conductivity of these substances and model parameters were dete (more) rmined using experimental data from the literature. The proposed general Padé model shows to be adequate to estimate the properties studied, obtaining deviations similar or lower than those of other highly non-linear models.

Diesel engines have proved their utility in transport, agriculture and power sector. Environmental norms and scared fossil fuel have attracted the attention to switch the energy demand to alternative energy source. Oil derived from Jatropha curcas plant has been considered as a sustainable substitute to diesel fuel. However, use of straight vegetable oil has encountered problem due to its high viscosity. The aim of present work is to reduce the viscosity of oil by heating from exhaust gases before fed to the engine, the study of effects of FIT (fuel inlet temperature) on engine performance and emissions using a dual fuel engine test rig with an appropriately designed shell and tube heat exchanger (with exhaust bypass arrangement). Heat exchanger was operated in such a way that it could give desired FIT. Results show that BTE (brake thermal efficiency) of engine was lower and BSEC (brake specific energy consumption) was higher when the engine was fueled with Jatropha oil as compared to diesel fuel. Increase in fuel inlet temperature resulted in increase of BTE and reduction in BSEC. Emissions of NO{sub x} from Jatropha oil during the experimental range were lower than diesel fuel and it increases with increase in FIT. CO (carbon monoxide), HC (hydrocarbon), CO{sub 2} (carbon dioxide) emissions from Jatropha oil were found higher than diesel fuel. However, with increase in FIT, a downward trend was observed. Thus, by using heat exchanger preheated Jatropha oil can be a good substitute fuel for diesel engine in the near future. Optimal fuel inlet temperature was found to be 80 C considering the BTE, BSEC and gaseous emissions. (author)

In [1] and [2] and R502 alternatives R407A, R407B, R407C, R404A and R507 have been compared energetically with R22 by system testing. The configurations were air cooled evaporator, annular tube evaporator, shell and tube condenser and annular condenser. After testing R407C and R404A in systems with flat plate heat exchangers, the comparison with R22 has been done under constant conditions (constant refrigeration capacity and constant temperature difference of 5 K in the secondary refrigerant loop and in the cooling water loop). The smallest reduction of the C.O.P. (<8%) could be found for R407C as well as R404A using plate heat exchanger (annular heat exchanger<15%). The reason for the positive behaviour of the R407C system is mainly the increase of the dew point temperature at the exit of the evaporator in comparison with annular evaporation. (orig.) [Deutsch] In [1] und [2] wurden die R22- bzw. R502-Alternativen R407A, R407B, R407C, R404A und R507 einer vergleichenden energetischen Bewertung zu R22 durch Anlagenleistungsmessungen mit Anlagenkonfigurationen, die sich mit luftbeaufschlagtem Verdampfer, Koaxial-Verdampfer, Rohrbuendel- und Koaxial-Verfluessiger kombinieren lassen, unterzogen. Anknuepfend an diese Untersuchungen wurde fuer die FKW-Gemische R407C und R404A bei Einsatz von Platten-Waermeuebertragern eine energetische Bewertung im Vergleich zu R22 durch Anlagenleistungsmessungen bei konstanten aeusseren Bedingungen (Temperaturspreizung des Kaelte-/Waermetraegers 5 K, konstante Kaelteleistung) vorgenommen. Die geringsten Leistungszahleinbussen (<8%) im Vergleich zu R22 traten sowohl mit R407C als auch mit R404A bei Einsatz von Platten-Waermeuebertragern auf (Koaxial-Waermeuebertrager<15%). Ursache fuer dieses guenstige Verhalten bei Einsatz von R407C ist im wesentlichen die groessere Taupunkttemperaturanhebung am Verdampferaustritt im Vergleich zum Koaxial-Verdampfer. (orig.)

Aerodynamics of a particle-laden gas jet entering the secondary side of a shell-and-tube heat exchanger from a tube guillotine breach, determines to a large extent radioactive retention in the break stage of the steam generator (SG) during hypothetical SGTR accident sequences in pressurized nuclear water reactors (PWRs). These scenarios were shown to be risk-dominant in PWRs. The major insights gained from a set of experiments into such aerodynamics are summarized in this paper. A scaled-down mock-up with representative dimensions of a real SG was built. Two-dimensional (2D) PIV technique was used to characterize the flow field in the space between the breach and the neighbor tubes in the gas flow range investigated (Re{sub D} = 0.8-2.7 x 10{sup 5}). Pitot tube measurements and CFD simulations were used to discuss and complement PIV data. The results, reported mainly in terms of velocity and turbulent intensity profiles, show that jet penetration and gas entrainment are considerably enhanced when increasing Re{sub D}. The presence of tubes was observed to distort the jet shape and to foster gas entrainment with respect to a jet expansion free of tubes. Turbulence intensity level close to the breach increases linearly with Re{sub D}. Account of this information into aerosol modeling will enhance predictive capability of inertial impaction and turbulent deposition equations. (author)

Stationary storage of hydrogen permits one to make hydrogen now and use it later. With stationary hydrogen storage, one can use excess electrical generation capacity to power an electrolyzer, and store the resultant hydrogen for later use or transshipment. One can also use stationary hydrogen as a buffer at fueling stations to accommodate non-steady fueling demand, thus permitting the hydrogen supply system (e.g., methane reformer or electrolyzer) to be sized to meet the average, rather than the peak, demand. We at ADL designed, built, and tested a stationary hydrogen storage device that thermally couples a high-temperature metal hydride to a phase change material (PCM). The PCM captures and stores the heat of the hydriding reaction as its own heat of fusion (that is, it melts), and subsequently returns that heat of fusion (by freezing) to facilitate the dehydriding reaction. A key component of this stationary hydrogen storage device is the metal hydride itself. We used nickel-coated magnesium powder (NCMP) - magnesium particles coated with a thin layer of nickel by means of chemical vapor deposition (CVD). Magnesium hydride can store a higher weight fraction of hydrogen than any other practical metal hydride, and it is less expensive than any other metal hydride. We designed and constructed an experimental NCM/PCM reactor out of 310 stainless steel in the form of a shell-and-tube heat exchanger, with the tube side packed with NCMP and the shell side filled with a eutectic mixture of NaCL, KCl, and MgCl{sub 2}. Our experimental results indicate that with proper attention to limiting thermal losses, our overall efficiency will exceed 90% (DOE goal: >75%) and our overall system cost will be only 33% (DOE goal: <50%) of the value of the delivered hydrogen. It appears that NCMP can be used to purify hydrogen streams and store hydrogen at the same time. These prospects make the NCMP/PCM reactor an attractive component in a reformer-based hydrogen fueling station.

The objectives that our development work addressed are: (1) Establish through lab tests a salt eutectic with a melting point of about 250 F and a working range of 250 to 1800 F. (2) Establish the most economical material of construction for the screened salt eutectics identified in the first objective. (3) Establish the material of construction for the salt heater liner. Objectives 2 and 3 were determined through corrosion tests using selected metallurgical samples. Successful completion of the above-stated goals will be incorporated in a heat recovery design that can be used in high temperature processes and furnaces, typical of which is the glass melting process. The process design incorporates the following unit operations: a vertical batch heater (whereby the batch flows down through tubes in a shell and tube exchanger; a molten salt eutectic is circulated on the shell side); a molten salt heater utilizing furnace flue gas in a radiation type heater (molten salt is circulated in the annular space between the inner and outer shells of the vertical heater, and flue gas passes from the furnace exhaust through the inner shell of the heater); a cantilever type molten salt circulating pump; and a jacketed mixer/conveyor to drive off moisture from the batch prior to feeding the batch to the vertical batch heater. Historically, radiation heaters, when applied to glass or fiberglass furnace recuperation, have experienced failures due to uneven heat flux rates, which increases internal stresses and spot overheating conditions. Low heat transfer coefficients result in requirements for large heat transfer surface areas in gas to gas or gas to air exchangers. Fouling is another factor that results in lower unit availability and reduced performance. These factors are accommodated in this process by the incorporation of several design features. The salt heater will be a vertical double wall radiation design, similar to radiation air heaters used in high temperature heat recovery. The unit utilizes an inner shell that the furnace exhaust gas passes through: this provides essentially a self-cleaning surface. Utilization of radiation air heaters in fiberglass furnaces has demonstrated that the inner shell provides a surface from which molten ash can drain down. The molten salt eutectic will be pumped through the annulus between this inner wall and the outer wall of the unit. The annular space tempering via the molten salt will promote more uniform expansion for the unit, and thereby promote more uniform heat flux rates. Heat transfer would be via radiation mainly, with a minor convective contributor.

The objective of this study was (i) to assess the present state of technology of reformers that convert methanol (or other alternative fuels) to a hydrogen-rich gas mixture for use in a fuel cell, and (ii) to identify the R D needs for developing reformers for transportation applications. Steam reforming and partial oxidation are the two basic types of fuel reforming processes. The former is endothermic while the latter is exothermic. Reformers are therefore typically designed as heat exchange systems, and the variety of designs used includes shell-and-tube, packed bed, annular, plate, and cyclic bed types. Catalysts used include noble metals and oxides of Cu, Zn, Cr, Al, Ni, and La. For transportation applications a reformer must be compact, lightweight, and rugged. It must also be capable of rapid start-up and good dynamic performance responsive to fluctuating loads. A partial oxidation reformer is likely to be better than a steam reformer based on these considerations, although its fuel conversion efficiency is expected to be lower than that of a steam reformer. A steam reformer better lends itself to thermal integration with the fuel cell system; however, the thermal independence of the reformer from the fuel cell stack is likely to yield much better dynamic performance of the reformer and the fuel cell propulsion power system. For both steam reforming and partial oxidation reforming, research is needed to develop compact, fast start-up, and dynamically responsive reformers. For transportation applications, steam reformers are likely to prove best for fuel cell/battery hybrid power systems, and partial oxidation reformers are likely to be the choice for stand-alone fuel cell power systems.

Latent thermal energy storage system (LTES) is an integral part of concentrating solar power (CSP) plants for storing sun's energy during its intermittent diurnal availability in the form of latent heat of a phase change material (PCM). The advantages of an LTES include its isothermal operation and high energy storage density, while the low thermal conductivity of the PCM used in LTES poses a significant disadvantage due to the reduction in the rate at which the PCM can be melted (charging) or solidified (discharging). The present study considers an approach to reducing the thermal resistance of LTES through embedding heat pipes to augment the energy transfer from the heat transfer fluid (HTF) to the PCM. Using a thermal resistance network model of a shell and tube LTES with embedded heat ...

A novel dry-expansion shell-and-tube evaporator (DESTE) integrated with function of defouling was developed as a component of wastewater source heat pump (WWSHP). To compare the performance of the DESTE-WWSHP with the conventional immersed evaporator (IE) based wastewater source heat pump (IE-WWSHP), an experimental platform was built by installing a DESTE and an IE unit in parallel in a same WWSHP system. The performance tests were conducted with the wastewater collected from downstream of a commercial sauna center in Shenzhen, China. Several operating parameters were investigated, including water heating capacity, coefficient of performance (COP), hot water temperature settings, wastewater discharge rate/pattern, and hot water discharge mode (continuous or intermittent). Results showed t...

In fiscal year 2003, test cell 23 of the Research Combustion Laboratory (RCL 23) at the NASA Glenn Research Center was upgraded with the addition of gaseous hydrogen as a working propellant and the addition of a 450-psig air-supply system. Test flexibility was further enhanced by upgrades to the facility control systems. RCL 23 can now test with gaseous hydrogen flow rates up to 0.05 lbm/sec and jet fuel flow rates up to 0.62 lbm/sec. Research airflow rates up to 3 lbm/sec are possible with the 450-psig supply system over a range of inlet temperatures. Nonvitiated, heated air is supplied from a shell and tube heat exchanger. The maximum nonvitiated facility air temperature is 1100 F at 1.5 lbm/sec. Research-section exhaust temperatures are limited to 3200 F because of material and cooling capacity limits. A variety of support systems are available depending on the research hardware configuration. Test section ignition can be provided via either a hydrogen air torch system or an electronic spark system. Emissions measurements are obtained with either pneumatically or electromechanically actuated gas sample probes, and the electromechanical system allows for radial measurements at a user-specified axial location for measurement of emissions profiles. Gas analysis data can be obtained for a variety of species, including carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NO and NOx), oxygen (O2), unburnt hydrocarbons, and unburnt hydrogen. Facility control is accomplished with a programmable logic control system. Facility operations have been upgraded to a system based on graphical user interface control screens. A data system is available for real-time acquisition and monitoring of both measurements in engineering units and performance calculations. The upgrades have made RCL 23 a highly flexible facility for research into low emissions gas turbine combustor concepts, and the flame tube configuration inherently allows for a variety of fuel nozzle configurations to be tested in a cost-effective manner. RCL 23 is poised to be a leading facility for developing modern low-emission fuel nozzles for use with jet fuel and alternative fuels.

In order not to increase energy consumption by introducing a secondary refrigerant, the use of ice slurry may be very interesting. Heat transfer coefficient and pressure drop for ice slurry flowing in a horizontal pipe have been measured. The stainless steel pipe (ID 21.6 mm) is heated by condensing R134a outside the pipe. The heat input is supplied by an electrical heater evaporating R134a. The heat flux is assumed to be constant over the whole surface and the heat transfer coefficient is calculated using the temperature difference and a known heat transfer coefficient for condensing R134a. The measurements show high heat transfer coefficients with melting ice slurry. The heat transfer coefficient increases with increasing ice concentration and increasing velocities. A correlation for calculating the heat transfer coefficient is developed. An industrial shell-and-tube condenser was tested with ice slurry. The overall heat transfer coefficient was measured and showed increasing value with increasing ice concentration. From the collected data the heat transfer coefficient for condensing CO{sub 2} was calculated The heat transfer coefficient showed agreement with the calculated values fro Nusselt`s theory. (au)

A new computational program has been developed in order to design single stage compression heat pumps. This software, named CICLO 1.0 allows the design of water-water, water-air, air-water and air-air heat pumps, for industrial and residential applications. CICLO 1.0 simulates three types of compressors: reciprocating, screw and scroll. Also has a data base created with REFPROP software which includes eleven refrigerants. The condenser and evaporator simulation includes global conductance (UA) determination, and when one or both are shell and tube's type, this software shows the even number of tube passes by shell. The software determines the best compressor and refrigerant setup taking the COP as a parameter; in order to obtain this, is necessary to know the inlet/outlet conditions of the fluid to be heated, the inlet conditions of the fluid that gives heat, and the electric motor efficiency that drives the compressor. The afforded results by CICLO 1.0 are: operation conditions from compression cycle, that means, pressures and temperatures at the inlet/outlet from every heat pump component are determined: as well as refrigerant mass flux, COP, power required by compressor, volumetric and isentropic efficiencies, heat exchangers global conductance and more data. CICLO 1.0 has been executed with heat pump data that nowadays are operating, and the results from the simulation have been very similar each other with data reported from operational facilities. [Spanish] Se ha desarrollado un nuevo programa computacional para el diseno de bombas de calor por compresion de vapor de una sola etapa. Este programa, CICLO 1.0, permite el diseno de bombas de calor de tipo: agua-agua, agua-aire, aire-agua y aire-aire, que se utilicen para aplicaciones industriales, de servicios y residenciales. CICLO 1.0 simula tres tipos de compresores: reciprocante, de tornillo y scroll: cuenta con una base de datos de refrigerantes creada con el programa REFPROP la cual incluye once refrigerantes. La simulacion del condensador y del evaporador incluye la determinacion de su conductancia global (UA), y cuando alguno de estos es del tipo coraza y tubos, se indica el numero de pasos pares de tubos por coraza. Dadas las condiciones de entrada y de salida del fluido que se desea calentar, las condiciones del fluido que cede calor, y la eficiencia electrica del motor que impulsa al compresor; el programa determina la mejor combinacion de compresor y refrigerante, tomando como criterio el COP. Los resultados que brinda CICLO 1.0 son: condiciones de operacion del ciclo de compresion, es decir, presiones y temperaturas a la entrada y salida de cada uno de los componentes que constituyen la bomba de calor, flujo masico de refrigerante, COP, potencia requerida en el compresor, asi como su eficiencia volumetrica e isoentropica, conductancia global de los intercambiadores y otros datos. Se ha ejecutado CICLO 1.0 con datos de bombas de calor que operan actualmente, y los resultados obtenidos de la simulacion han sido muy similares con los reportados de la operacion de dichas instalaciones.

This paper presents a detailed analysis of the heat and mass transfer processes during the absorption of ammonia into water in a co-current vertical tubular absorber. The absorber configuration is of the shell and tubes type. The absorption process progresses as the vapour and liquid contact inside the tubes. Water is used as the absorber cooling medium. A differential mathematical model has been developed on the basis of mass and energy balances and heat and mass transfer equations, in order to provide further understanding of the absorber behaviour. The model takes into account separately for the churn, slug and bubbly flow patterns experimentally forecasted in this type of absorption processes inside vertical tubes and considers the simultaneous heat and mass transfer processes in both liquid and vapour phases, as well as heat transfer to the cooling medium. The model equations have been solved using the finite-difference method. Results obtained for specific data are depicted to show local values of the most important variables all along the absorber length. Parametric analyses have been performed to show the influence of design parameters and operating conditions on the absorber performance. The effect of the heat and mass transfer coefficients has also been evaluated. (authors)

An air heating and cooling system for a building includes an expansion-type refrigeration circuit and a heat engine. The refrigeration circuit includes two heat exchangers, one of which is communicated with a source of indoor air from the building and the other of which is communicated with a source of air from outside the building. The heat engine includes a heat rejection circuit having a source of rejected heat and a primary heat exchanger connected to the source of rejected heat. The heat rejection circuit also includes an evaporator in heat exchange relation with the primary heat exchanger, a heat engine indoor heat exchanger, and a heat engine outdoor heat exchanger. The indoor heat exchangers are disposed in series air flow relationship, with the heat engine indoor heat exchanger being disposed downstream from the refrigeration circuit indoor heat exchanger. The outdoor heat exchangers are also disposed in series air flow relationship, with the heat engine outdoor heat exchanger disposed downstream from the refrigeration circuit outdoor heat exchanger. A common fluid is used in both of the indoor heat exchanges and in both of the outdoor heat exchangers. In a first embodiment, the heat engine is a Rankine cycle engine. In a second embodiment, the heat engine is a non-Rankine cycle engine.

This book presents the papers given at a symposium on the use of heat exchangers in the industrial plants. Topics considered include the US DOE and GRI research programs, advanced fixed boundary heat exchanger technology, commercial heat exchanger applications, thermo-hydraulic performance of heat-transfer equipment, field tests, the corrosion of heat exchanger materials, economics, cost benefit analysis, payback, and advanced assembly and materials.

Horizontal ground heat exchangers have been widely used in many countries as the heat source for ground-source heat pump systems. When abundant land space is available for the installation of ground heat exchangers, the horizontal ground heat exchangers provide a cost-effective choice because the installation costs of horizontal ground heat exchangers are much lower than those of vertical ground heat exchangers. Slinky-coil horizontal ground heat exchangers, which are basically coiled ground heat exchangers, require less land space than conventional straight horizontal ground heat exchangers because of the higher installation density of heat exchange pipes per given area. However, at present, the slinky-coil horizontal ground heat exchangers tend to be over- or undersized because of the la...

A heat pump system includes, in an operable relationship for transferring heat between an exterior atmosphere and an interior atmosphere via a fluid refrigerant: a compressor; an interior heat exchanger; an exterior heat exchanger; an accumulator; and means for heating the accumulator in order to defrost the exterior heat exchanger.

A heat pipe arrangement for exchanging heat between two different temperature fluids. The heat pipe arrangement is in a ounterflow relationship to increase the efficiency of the coupling of the heat from a heat source to a heat sink.

Vahterus Oy, located at Kalanti, has manufactured heat exchangers since the beginning of 1990s. About 90% of the equipment produced are exported. In the PSHE (Plate and Shell) solution of the Vahterus heat exchanger the heat is transferred by round plated welded to form a compact package, which is assembled into a cylindrical steel casing. The heat exchanger contains no gaskets or soldered joints, which eliminates the leak risks. Traditional heat exchanges are usually operated at higher temperatures and pressures, but the heat transfer capacities of them are lower. Plate heat exchangers, on the other hand, are efficient, but the application range of them is narrow. Additionally, the rubber gasket of the heat exchange plates, sealing the joints of the heat exchanging plates, does not stand high pressures or temperatures, or corroding fluids. The new welded plate heat exchanger combine the pressure and temperature resistance of tube heat exchangers and the high heat exchange capacity of plate heat exchangers. The new corrosion resisting heat exchanger can be applied for especially hard conditions. The operating temperature range of the PSHE heat exchanger is - 200 - 900 deg C. The pressure resistance is as high as 100 bar. The space requirement of PSHE is only one tenth of the space requirement of traditional tube heat exchangers. Adjusting the number of heat exchanging plates can change the capacity of the heat exchanger. Power range of the heat exchanger can be as high as 80 MW. Due to the corrosion preventive construction and the small dimension the PSHE heat exchanger can be applied for refrigerators using ammonia as refrigerant. These kinds of new Vahterus heat exchangers are in use in 60 countries in more than 2000 refrigerators.

seven centralized heat collection devices (liquid to liquid heat exchangers and pin-fln coldplates) ... the GSE heat exchanger to a ground coolant unit. The Flash ..... obtained for flight verification and math model correlation. CONCLUSIONS ...

Regenerative heat exchangers are described for transferring heat between hot and cold fluids. The heat exchangers have seal-leakage rates significantly less than those of conventional regenerative heat exchangers because the matrix is discontinuously moved and is releasably sealed while in a stationary position. Both rotary and modular heat exchangers are described. Also described are methods for transferring heat between a hot and cold fluid using the discontinuous movement of matrices.

This heating apparatus comprises an electrical infra-red heaters for example, a tungsten halogen lamp with a red quartz outer sleeve which is disposed within a soldered coil heat exchanger. Oil is arranged to be circulated through the heat exchanger. In use, the infra-red heater heats by radiation oil circulated through the heat exchanger. The heated oil is then led to a flat-plate heat exchanger wherein heat passes to circulating water. The circulating water is led to a static water vessel and subsequently via a motorised valve to radiator units (not shown) of a central heating system. Additionally, the heated oil is led in parallel through a heat exchanger (not shown) disposed within a water tank thereby to heat water in the tank. The valve is only opened when the water in the vessel reaches a predetermined temperature. The heat exchangers may be surrounded by heat insulating material or the apparatus may be enclosed by an air heating casing. (Author)

Heat exchangers of different types are used in processes for heat recovery. In recuperators, heat is transmitted across solid separating surfaces (interfaces). The heat exchanges fluids are completely separated by the solid surfaces, so that there is no exchange of material. Heat transfere is largely done in the steady state, where a constant temperature profile is formed in the separating wall. Forms of recuperators are also discussed, which are best used for heat recovery in tall buildings. First, plate heat exchangers are described in their configuration and their method of operation. The pipe bundle heat exchanger is then dealt with. (BR).

The advantage of using a plate-fin heat exchanger in low-temperature gas separation is discussed in connection with its high heat transfer and gas purification characteristics. Equations are derived for the calculation of the coefficients and dimensions of the heat exchanger block. An illustration of the seriousness of now maldistribution in a heat exchanger is given. (B.O.G.)

This patent describes a heating system, comprising a heating compartment, a tubular heat exchanger within the heating compartment, heat input means for supplying hot fluid into the heat exchanger for flowing therein, and means for causing other fluid to flow across the heat exchanger in a direction generally transverse to the longitudinal axis of the heat exchanger for transfer of thermal energy from the heat exchanger to such other fluid flowing thereacross. The heat exchanger has an egg-shaped cross-section oriented with its narrow end facing downstream of the flow of such other fluid, the heating compartment having wall means cooperatively positioned with respect to the heat exchanger further to direct flow of such other fluid on both sides of the heat exchanger. The wall means includes a wall adjacent to and generally parallel to the longitudinal axis of the heat exchanger, and the major axis of the egg-shape cross-section is oriented at an angle to the direction of flow of such other fluid and at an angle to the wall with its narrower end nearest the wall to define with such wall a restricted flow passage for such other fluid at the narrower end. Here such other fluid flowing across the heat exchanger will be caused to flow closely over substantially the entire exterior extent thereof to maximize thermal energy transfer while minimizing heat concentration at the downstream side of the heat exchanger.

In this paper a dynamic model of a 1:1 refrigeration system is presented. The main modelling effort has been concentrated on a lumped parameter model of a shell and tube condenser. The model has shown good resemblance with experimental data from a test rig, regarding as well the static as the dynami...

The subject is discussed under the headings: advantages of explosive welding; principle of explosive welding; explosive welding of tubes; metallurgy of explosive welds (micrographs; microhardness); tubular heat exchangers; plugging; sleeving; retubing; construction of new heat exchangers; thermal sleeves.

The gasdynamic performance equation for large-scale dry cooling towers is generalized to include mechanical draft as well as natural draft. A sequence of four elements; heat-exchanger, fan, heat-exchanger, fan, are contemplated in the final result which t...

The heat pipe - heat exchanger assembly was housed within a vacuum chamber held at a ... Keywords: Heat pipe, space, nuclear, transient, cooling, compact, reactor. BACKGROUND ..... to heat pipe dry out or possibly stagnation block.

Jul 25, 2012 ... Thermal Analysis and Modeling; System Automation and Health Management ... Pumps, Heat Exchangers, Instrumentationn; Advanced Propellant Servicing ... Aerogels for unique ground heat leak applications; Multi-Layer ...

This report covers the area of industrial heat pumps. After a brief introduction as to where to use a heat pump, the topics examined include, heat pump fluids, sizing and control, process integration and heat pumps, steam compression and HVR, heat pump assisted distillation and drying by heat pumps. Heat exchangers and compressors for heat pumps are areas covered in the appendices.

Subjects covered: introduction to heat exchanger fouling; basic fouling models; precipitation fouling; CaCO[sub 3] scaling; black liquor fouling; geothermal brine fouling; particulate fouling; chemical reaction fouling; fouling of enhanced surfaces - experimental results; fouling of enhanced surfaces - theory; chemical fouling mitigation; mechanical fouling mitigation; heat exchanger design for fouling conditions; fouling monitoring systems; cleaning of heat exchangers; and economic aspects of heat exchanger fouling.

Geothermal (ground-source) heat pumps (GHPs) are an efficient alternative to conventional methods of conditioning buildings. However, GHP systems can have relatively high installation costs because of the ground heat exchanger. Proper sizing of the exchanger is critical to performance. Vertical U-tube heat exchangers are commonly used as the ground heat exchanger, but the design and determination of the operating performance is difficult because of the unique heat transfer situation. This paper proposes a U-tube heat exchanger model based on finite-difference methods that can be used in system design and annual performance simulations.

A regenerator apparatus is described, comprising: a shell portion containing spent catalyst from a catalytic reactor as a heat exchange medium; and heat exchanger means containing another heat exchange medium consisting of upper manifold means; lower manifold means; and a plurality of substantially C-shaped tubes interconnecting the upper and lower manifold means.

Computer program predicts heat-exchanger performance under variety of conditions. Program provides rapid means of calculating distribution of fluid and wall temperatures, fuel deposit formation, and pressure losses at various locations in heat exchanger. Developed for use with heat exchanger that vaporizes fuel prior to fuel ignition; other applications possible.

During the last ten years, several design tools were developed for ground loop heat exchangers. One such tool is the GLHEPro, used for commercial building loop heat exchangers. The simulation of the temperature response of the ground loop heat exchanger to monthly heating and cooling loads and monthly peak heating and cooling demands over several years forms the basis for the design methodology. Meeting the minimum and maximum heat pump entering fluid temperatures specifications set by the user is effected by automatically adjusting the ground loop heat exchanger size. The temperature response predictions comprises three steps. In the first step, the building heating and cooling loads are translated to heat extraction and heat rejection rates using a simple heat pump model. In the second step, a detailed conduction heat transfer simulation, developed by Eskilson forms the basis for the long term temperature response of a ground loop heat exchanger to heat rejection and extraction. Thirdly, a simple analytical approximation for the response of the ground loop heat exchanger to a single peak heat extraction or rejection pulse is used for the short term temperature response of the ground loop heat exchanger. To further illustrate the technical aspects underlying the program, an example of a ground loop heat exchanger for a 27,000 square foot office building in Ottawa, Ontario is discussed. 9 refs., 12 figs.

In agricultural biogas plants organic material (manure) is decomposed in a fermentation process to low-molecular compounds, thereby producing combustible biogas. One part of the biogas energy is used for heating the manure up to a temperature necessary for the fermentation process. The heat contained in the fermented manure can be used for heating up the fresh manure in a manure/manure heat exchanger. Subject of the project was the construction and test of a 'pit heat exchanger' and a 'pipe heat exchanger' and the examination of their efficiency. For the 'pit heat exchanger' an evaluation of its economy was made. With 45 figs., 20 tabs.

In contrast to well-known heat exchangers with liquid or gaseous heat transfer fluids this invention presents a new principle. The surface of an heat pipe has been enlarged by sintering spheres. These spheres are fixed in the pipe wall or with the heat sheet and extract the heat very efficiently. More thermal energy can be transfered to the same volume which has been heated by focused beams. The thermal efficiency could be increased. The new heat exchanger with sintering spheres could also be used in air heating systems or in a combined heat exchanger with or without sintering spheres systems.

Heat storage offers essential thermal energy saving for heating. A ground heat store equipped with heat pipes connecting it with a heat source and to the user is considered in this paper. It has been shown that such a heat exchanging system along with a batch energy source meets, to a considerable extent, house heating requirements. (author).

The objective of this work is to obtain the Performance test data for the passive residual heat removal (RHR) heat exchanger in the advanced PWR. The RHR heat exchanger is designed to remove the decay heat with combined effects of the natural circulation of water by means of the thermosyphon at the inside and the natural convection of the air at the outside. Two test models were made to simulate the RHR heat exchanger. The one is the single bundle test model which consisted of a finned tubular heat exchanger unit. The other is the multi-bundle test model which has the finned tubular heat exchanger consisting of ten bundles of tubular units. The Maximum heat removal capabilities of each model were investigated. The cooling water flow rates by the thermosyphon were measured and were in good agreement with the theoretical predictions. The effects of chimney and elevation between the heater and the heat exchanger were investigated.

An inexpensive process for the direct heating of benzolized oil by heat exchange in the ascension pipes of a coke oven has been developed and successfully applied to operating ovens. The authors report experiments on: 1) the amount of heat recovered; 2) the prevention of unwanted coking; 3) carbon deposition in the ascension pipes; and 4) deterioration of heat exchange performance. 4 figs.

A pig nursery building was divided into two equal rooms, one with a heat exchanger and one with a solar block wall. The average air inlet temperatures were 16.4/sup 0/C in the heat exchanger room and 11.9/sup 0/C in the solar heated room. Supplemental heating costs were 67% higher in the solar block wall room.

Evaluation of the rate of surface heat exchange between the water and air has become very significant because of the need to determine the thermal response of streams to heat inputs. The different mechanisms of heat exchange that contribute to the total heat exchange were discussed and the various empirical formular to compute each of the components, as developed by various investigators, were presented and discussed. The suitability of each empirical formula was examined. The methods to linearize the total heat exchange rate were reviewed and a new linearized relation was proposed. General equations, suitable for winter-regime conditions, were presented to compute the coefficients of the linearized heat loss model. (GRA)

In this paper, a cross flow plate type heat exchanger, operating with unmixed fluids, was analysed with balanced cross flow. For this aim, a cross flow plate type heat exchanger was developed and manufactured in the laboratory. The heat exchanger was tested with an applicable experimental set up, and temperatures, velocity of the air and the pressure losses occurring in the system were measured so that the effectiveness of the heat exchanger has been determined. The minimum entropy generation number has been taken into consideration with respect to the second law of thermodynamics for the heat exchanger in this analysis. The minimum entropy generation number depends on parameters such as optimum flow path length, dimensionless mass velocity, dimensionless heat transfer area and dimensionless heat transfer volume. The variations between the entropy generation number and these parameters were analysed for the manufactured heat exchanger and introduced with their graphics. (author)

Octo-Block HX design concept finite element model . ..... heat pipes pass through a heat exchanger (HX) that extracts heat from the pipes and transfers it into a helium- (He-) argon gas ...... resistance heaters on the ground. This Technical ...

The basic features of the energetics of the tropical atmosphere and the role of radiation .... hydrologiclprocesses,. - heat exchange in the soil. .... turbulent heat flux as a residual term of the heat budget equation with allow- ance and with no ...

The results of heat-transfer and friction studies in bundles of twisted tubes and rods with spiral wire-wrap spacers are analyzed, and recommendations are given for calculating the heat-transfer coefficient in heat exchangers using twisted tubes.

This paper compares the energy performance and economics of a direct two-stage ammonia system to an ammonia-carbon dioxide cascade system for low temperature (below -40 ^oC) applications. Component and system models are developed for both the direct ammonia and the ammonia-carbon dioxide cascade options. These models provide the basis for quantifying the relative operating costs for both systems on annual and life-cycle bases. The analysis shows that the ammonia-carbon dioxide cascade system option using a shell-and-tube cascade condenser offers the potential for increased energy efficiency when compared to a direct two-stage ammonia system when operating with evaporating temperatures that are below -46.2 ^oC. For the cascade system option, the analysis shows that a shell-and-tube cascade ...

A thermal storage heater system for heating fluids includes a storage tank for accumulating and storing energy in the form of a quantity liquid heated to a high temperature by an electric immersion heating element in the tank. A source of a first fluid to be heated is connected to the inlets of pilot and primary heat exchangers immersed in the high temperature liquid for transferring heat to the first fluid. A first circuit connects the outlet of the pilot heat exchanger to a point of use. A second fluid circuit connects the outlet of the primary heat exchanger to the point of use and includes a spring-loaded pressure sensitive check valve responsive to the flow rate in the first circuit for regulating the flow of fluid through the primary heat exchanger in response to a change in flow indicative of insufficient heating of the fluid by the pilot heat exchanger. The system includes an additional heat exchanger for heating a second fluid to be heated. The pilot, primary and additional heat exchangers each comprise at least one U-shaped tube immersed in the liquid with each tube having an inlet and an outlet aligned in a horizontal plane. A condenser is provided at the outlet of the pilot heat exchanger and additional heat exchanger for condensing any entrained steam in the heated fluid. The condenser for the additional heat exchanger includes a central spray tube connecting the source of second fluid to the inlet of the U-shaped tube, a concentric outer shell connecting the outlet of the U-shaped tube to the point of use, and a radially corrugated imperforate baffle therebetween.

According to this invention, the chimney outlet is replaced by a heat recuperator consisting essentially of heat exchange tubes immersed in a heat accumulating material, from which the heat is ultimately extracted. The invention also applies to a process for extracting heat using the device, which is applicable to domestic heating use.

According to the collected data the available industrial waste heat does not exceed 6% of the total Danish space heating consumption. Nevertheless waste heat can be effectively utilized from the 288 water treament plants, from refineries and chemical industry. Waste heat can be supplied to the consumer either by means of heat pumps or direct heat exchange.

The Heat Pipe Stirling Engine (HP-1000), a free-piston Stirling engine incorporating three heat exchanger modules, each having a sodium filled heat pipe, has been tested at the NASA-Lewis Research Center as part of the Civil Space Technology Initiative (CSTI). The heat exchanger modules were designed to reduce the number of potential flow leak paths in the heat exchanger assembly and incorporate a heat pipe as the link between the heat source and the engine. An existing RE-1000 free-piston Stirling engine was modified to operate using the heat exchanger modules. This paper describes heat exchanger module and engine performance during baseline testing. Condenser temperature profiles, brake power, and efficiency are presented and discussed.

The waste heat recovery by heat pipes is accepted as an excellent way of saving energy and preventing global warming. This paper is a literature review of the application of heat pipes heat exchangers for the heat recovery that is focused on the energy saving and the enhanced effectiveness of the conventional heat pipe (CHP), two-phase closed thermosyphon (TPCT) and oscillating heat pipe (OHP) heat exchangers. The relevant papers were allocated into three main categories, and the experimental studies were summarized. These research papers were analyzed to support future works. Finally, the parameters of effectiveness of the CHP, TPCT and OHP heat exchangers were described. This review article provides additional information for the design of heat pipe heat exchangers with optimum condition...

Double-spiral-type equipment is proposed as a new compact heat exchanger. Initially, the behavior of heat transfer coefficients is quantitatively determined through experiments of the heat exchange between hot and cold water flows in the exchanger. Subsequently, the heat-recipient water is changed with phase change material (PCM)–water slurry to ascertain the effects of PCM-melting on heat transfer enhancement through direct measurements of heat transfer rates. By appropriately evaluating the physical properties of the slurries with PCM-melting, we finally propose a heat transfer correlation which is applicable to both the water and slurry flows.   

In the present work, the design and analysis of a multi-block heat exchanger has been carried out by applying the concept of constructal theory proposed by Bejan. The heat exchanger works on the principle of developing laminar flow in each block carefully designed to avoid fully developed heat transfer coefficient. The additional thermal interaction is provided by the special design allowing heat transfer in ports as well as collecting and distributing channels. Numerical simulations were carried out for different values of heat capacity rate ratios on finned and unfinned constructal heat exchangers and four cross flow heat exchangers (two finned and two unfinned). In all the heat exchangers the heat transfer area is kept the same. To validate the numerical results, experiments were conducted keeping the heat transfer area and boundary conditions same as that of the numerical simulations. The results show that the effectiveness of the constructal heat exchangers, both finned and unfinned, are higher by around 20% compared to that of the conventional cross flow heat exchangers under similar conditions. The experimental result confirms this enhancement and brings out the immense potential of this new type of heat exchanger. (author)

Set out herein is a solar heating panel adapted to exchange solar heat with fluids, the panel including a translucent upper surface covering the top of a rectangular enclosure, the enclosure further supporting a heat exchange panel. The heat exchange panel is provided with a plurality of tubular segments attached to the exposed surface thereof by which the solar rays received in the panel are reflected repeatedly until absorbed. It is contemplated to convey fluid around the tubular segments, the fluid thus exchanging heat therewith.

Heat exchanger networks are an integral part of chemical processes as they recover available heat and reduce utility consumption, thereby improving the overall economics of an industrial plant. This paper focuses on heat exchanger network design for multi-period operation wherein the operating conditions of a process may vary with time. A typical example is the hydrotreating process in petroleum refineries where the operators increase reactor temperature to compensate for catalyst deactivation. Superstructure based multi-period models for heat exchanger network design have been proposed previously employing deterministic optimisation algorithms, e.g. (Aaltola, 2002; Verheyen and Zhang, 2006). Stochastic optimisation algorithms have also been applied for the design of flexible heat exchange...

cold soa?ss the CM interior structure and equipment. ... exchanger, the entire cold plate network, and the suit heat exchanger. The CABIN TEMP ... of gas entering the CM. The capillaries which are wound around the hot glycol line serve two ...

Metal hydrides show great potential for hydrogen storage. However, for efficient hydrogen storage, thermal management is the technical barrier. Among the different heat exchangers proposed in the literature, finned tube heat exchangers are of great technological interest due to their adaptability to wide range of practical applications, high compactness and high heat transfer efficiency. In the present paper, the optimization of finned heat exchanger considering both enhanced heat transfer and vessel volume efficiency is conducted. A semi-analytical expression of heat transfer rate from a single fin is derived. The effects of fin dimension (fin thickness and radius) on the heat exchanger performance are studied. It was shown that the thermal resistance of the whole heat exchanger can be re...

In this paper, numerical simulation of a concentric tube heat exchanger is presented to determine the convective heat transfer coefficient and friction factor in a smooth tube. Increasing the convective heat transfer coefficient can increase heat transfer rate in a concentric tube heat exchanger from a given tubular surface area. This can be achieved by using heat transfer augmentation devices. This work constitutes the initial phase of the numerical simulation of heat transfer from tubes employing augmentation devices, such as twisted tapes, wire-coil inserts, for heat transfer enhancement. A computational fluid dynamics (CFD) simulation tool was developed with CFX software and the results obtained from the simulations are validated with the empirical correlations for a smooth tube heat exchanger. The difficulties associated with the simulation of a heat exchanger augmented with wire-coil inserts are discussed. (author)

In cold climates, mechanical ventilation systems with highly efficient heat recovery will experience problems with condensing water from the extracted humid indoor air. If the condensed water changes to ice in the heat exchanger, the airflow rate will quickly fall due to the increasing pressure drop. Preheating the inlet air (outdoor air) to a temperature above 0 degrees C before it enters the exchanger is one solution often used to solve the problem, however, this method reduces the energy saving potential significantly. To minimize the energy cost, a more efficient way to solve the freezing problem is therefore desirable. In this paper, the construction and test measurements of a new counter flow heat exchanger designed for cold climates are presented. The developed heat exchanger is capable of continuously defrosting itself without using supplementary heating. Other advantages of the developed beat exchanger are low pressure loss, cheap materials and a simple construction. The disadvantage is that the exchanger is big compared with other heat exchangers. In this paper, the new heat exchanger's efficiency is calculated theoretically and measured experimentally. The experiment shows that the heat exchanger is capable of continuously defrosting itself at outside air temperatures well below the freezing point while still maintaining a very high efficiency. Further analysis and development of a detailed simulation model of a counter flow air-to-air heat exchanger will be described in future articles.

In a fluidized bed of solid particles having one or more heat exchange tubes immersed therein, the rate of heat transfer between the fluidized particles and a fluid flowing through the immersed heat exchange tubes is controlled by rotating an arcuate shield apparatus about each tube to selectively expose various portions of the tube to the fluidized particles.

<p>A conventional heat exchanger consists of fluid channels with diameter larger than approximately 3 mm. Here, the phenomena around heat transfer and pressure drop are more or less well understood and can be well predicted. Newer and more compact heat exchangers use channels with smaller dia...

The conventional phosphoric acid fuel cell power generation system has such disadvantage that its waste heat recovery heat exchanger is corroded and deteriorated by phosphoric acid in the course of recovering the heat from the exhaust air from the fuel cell main body, resulting in the lowering of heat exchange performance. This invention solves the problem. In the invented phosphoric acid fuel cell power generation system, the heat transfer part of the waste heat recovery heat exchanger contacting with the exhaust gas is made of corrosion resistant material against phosphoric acid is employed. With this structure, neither corrosion nor deterioration takes place even if phosphoric acid is produced and attaches on the heat transfer surface of the waste heat recovery heat exchanger. Furthermore, a device is provided to wash down the phosphoric acid condensed on the heat transfer surface. Most of the heat transfer surface is installed vertically in the waste heat recovery heat exchanger. In this way, the degradation of waste heat recovery heat exchanger and the pressure loss are prevented. As for the phosphoric-acid-corrosion-resistant material, coatings of Teflon or ceramics are employed. 9 figs.

An air heating and cooling system for a building includes an expansion type refrigeration circuit and a vapor power circuit. The refrigeration circuit includes two heat exchangers, one of which is communicated with a source of indoor air from the building and the other of which is communicated with a source of air from outside the building. The vapor power circuit includes two heat exchangers, one of which is disposed in series air flow relationship with the indoor refrigeration circuit heat exchanger and the other of which is disposed in series air flow relationship with the outdoor refrigeration circuit heat exchanger. Fans powered by electricity generated by a vapor power circuit alternator circulate indoor air through the two indoor heat exchangers and circulate outside air through the two outdoor heat exchangers. The system is assembled as a single roof top unit, with a vapor power generator and turbine and compressor thermally insulated from the heat exchangers, and with the indoor heat exchangers thermally insulated from the outdoor heat exchangers.

For the corrosiveness gas (SOx, NOx, HCI, and HF) included in the exhaust waste heat of various heat facilities, the structure and applicability of heat exchanger developed by AIR FROHLICH in Switzerland were described. The heat exchanger by AIR FROHLICH used TEFLON material which is almost perfect for corrosion resistant. It is expected to contribute to a scheme for energy saving of environmental protection facility, such as FGD and collection of waste heat. 8 figs.

To bury absorber tubes in diaphragm wall as heat exchanger is a new energy saving technology. This paper is dedicated to study this new technology based on the field experiment at Shanghai Museum of Nature History. By the experiment, the heat transfer performance of heat exchanger in diaphragm wall and its impact factors including heat exchanger type, water velocity, inlet water temperature and operation mode were investigated. The test results show that (i) the heat exchange rate of W-shaped heat exchanger reached to 66.3 and 73.7W/m for tube type (a) and (b) at the inlet temperature of 35^oC, which are approximately 1.2-1.4 times higher than that of single U-shaped type (c); (ii) under the experimental condition, the reasonable water velocity is 0.6-0.9m/s; (iii) the exchange rate reache...

The work reported here is the preliminary analysis of two-phase Thermosyphon heat transfer performance with various alkali metals. Thermosyphon is a device for transporting heat from one point to another with quite extraordinary properties. Heat transport occurs via evaporation and condensation, and the heat transport fluid is re-circulated by gravitational force. With this mode of heat transfer, the thermosyphon has the capability to transport heat at high rates over appreciable distances, virtually isothermally and without any requirement for external pumping devices. For process heat, intermediate heat exchangers (IHX) are required to transfer heat from the NGNP to the hydrogen plant in the most efficient way possible. The production of power at higher efficiency using Brayton Cycle, and hydrogen production requires both heat at higher temperatures (up to 1000oC) and high effectiveness compact heat exchangers to transfer heat to either the power or process cycle. The purpose for selecting a compact heat exchanger is to maximize the heat transfer surface area per volume of heat exchanger; this has the benefit of reducing heat exchanger size and heat losses. The IHX design requirements are governed by the allowable temperature drop between the outlet of the NGNP (900oC, based on the current capabilities of NGNP), and the temperatures in the hydrogen production plant. Spiral Heat Exchangers (SHE’s) have superior heat transfer characteristics, and are less susceptible to fouling. Further, heat losses to surroundings are minimized because of its compact configuration. SHEs have never been examined for phase-change heat transfer applications. The research presented provides useful information for thermosyphon design and Spiral Heat Exchanger.

A multi-stage, isothermal, carbon monoxide preferential oxidation (PrOx) reactor comprising a plurality of serially arranged, catalyzed heat exchangers, each separated from the next by a mixing chamber for homogenizing the gases exiting one heat exchanger and entering the next. In a preferred embodiment, at least some of the air used in the PrOx reaction is injected directly into the mixing chamber between the catalyzed heat exchangers.

This emergency cooler for a fast neutron reactor is made by a heat exchanger placed into the hot liquid metal collector, a vertical tube beneath the heat exchanger and connecting the hot and the cold liquid metal collectors, a dome surrounding the upper end of the tube and fixed to the base of the heat exchanger and a system pressurizing or depressurizing the volume within the dome with inert gas.

Seventy three page report describes one year performance of commercial solar-energy hot-water system. Silicone oil is heat-exchange fluid in tested system, designed to meet needs of family of four. Roll-bend heat exchanger is wrapped around hot-water storage tank. Oil circulates through exchanger and flat-plat solar collectors. Auxiliary energy, to maintain temperature in storage tank, is supplied by 4,500-watt resistance-heating element.

The flue gas is cooled in an heat exchanger, washed in a water bath containing lime and reheated in the heat exchanger. Limestone powder is mixed into the gas prior to cooling so that neutralization of the formed sulfuric acid can be achieved. The coatings on the heat exchanger should be kept dry so that reduced reaction time can be attained by an infrasonic generator and the coatings being shaken loose by the generator.

A solar collector having a copper panel in a contiguous space relationship with a condenser-evaporator heat exchanger located under the panel, the panel having a honeycomb-like structure on its interior defining individual cells which are filled with zeolite loaded, in its adsorbed condition, with 18 to 20% by weight of water. The interior of the panel and heat exchanger are maintained at subatmospheric pressure of about 0.1 to 1 psia. The panel and heat exchanger are insulated on their lateral sides and bottoms and on the top of the heat exchange. The panel has a black coating on its top which is exposed to and absorbs solar energy. Surrounding the insulation (which supports the panel) is an extruded aluminum framework which supports a pair of spaced-apart glass panels above the solar panel. Water in conduits from a system for heating or cooling or both is connected to flow into an inlet and discharge from outlet of a finned coil received within the heat exchanger. The collector panel provides heat during the day through desorption and condensing of water vapor from the heated solar panel in the heat exchanger and cools at night by the re-adsorption of the water vapor from the heat exchanger which lowers the absolute pressure within the system and cools the heat exchange coils by evaporation.

The article describes the economy of exploiting heat from low-temperature geothermal sources for high-temperature heating of buildings using a heat pump. For the exploitation of low-temperature geothermal sources, a two stage heat pump with a heat exchanger was planned. The pump consists of two sing...

This work analyzes influence of anisotropy of anisotropic soil on the processes of heat transfer by ground heat exchangers used in ground-coupled heat pump systems. First, this paper uses the heat-source theory to develop several explicit exact solutions for heat conduction in anisotropic infinite or semi-infinite media with internal line, cylindrical-surface, or spiral-line sources. These solutions will reduce to common heat-source solutions for isotropic media. Next, these general solutions are applied to borehole ground heat exchangers and energy piles (or pile ground heat exchangers). Then, temperature responses of borehole and pile ground heat exchangers are examined in depth. Especially, the cylindrical-surface source model and the spiral-line source model are compared when applied t...

The potentiality of geocooling (i.e. free cooling) with borehole heat exchangers is analysed for low energy office buildings. The borehole heat exchanger field is coupled to a heat pump in winter and to the cold distribution system in summer through a flat plate heat exchanger. The cooling requirement satisfied by a direct heat transfer into the ground through the borehole heat exchangers is so-called geocooling. A dynamic system model has been developed to simulate the building, the emission of thermal energy through thermally activated building systems, the technical installation including the borehole heat exchanger field and the interconnected thermal interactions. Thermal comfort requirements determine the building energy needs and the size of the ground coupled system. A methodology ...

A small and light weight heat exchanger used for small helium refrigerator has been developed by Sumitomo Heavy Industries, Ltd. This heat exchanger is a laminated metal heat exchanger which consists of perforated aluminum metal plates and glassfiber reinforced plastic separators. The size is from 100 mm to 28 mm in diameter and about 300 mm in length. The weight is from 2.5 kg to 0.6 kg. Also it can be used between room temperature and liquid helium temperature. The thermal efficiency obtained has been more than 96%. The heat exchanger has been practically used for on-board helium refrigerator in Japanese National Railways' superconducting magnetic levitated trains.

Flow-induced vibration in heat exchangers has been a major cause of concern in the nuclear industry for several decades. Many incidents of failure of heat exchangers due to apparent flow-induced vibration have been reported through the USNRC incident reporting system. Almost all heat exchangers have to deal with this problem during their operation. The phenomenon has been studied since the 1970s and the database of experimental studies on flow-induced vibration is constantly updated with new findings and improved design criteria for heat exchangers.

Based on the JLab study and calculations, Linde made the following changes to the LR1610 heat exchanger. The LR 1610 redesign changed two different aspects of the original LR1610 design. The heat exchanger and the boiler are wrapped differently than the original LR1610 per the following: (A) Heat Exchanger - Section A - Current LR 1610 - 2 wraps - 1 path, Redesign - 2 wraps - 2 paths; Section B: Current LR 1610 - 2 wraps - 1 path, Redesign - 2 wraps - 2 paths; (B) Boiler: Current design - 1 wrap - 2 paths, Redesign - 1 wrap - 1 path. The contents of the attachments are: (1) Assembly - Pictures of the LR1610 Redesign Heat Exchanger after manufacturing; (2) Drawings - 3D and 2D drawings used to fabricate the Redesign LR1610 Heat Exchanger and the Precooler-Boiler; (3) Performance Curves - The expected performance curves and the TS diagram for a single proposed new compressor that is more capacity than the RSX; (4) Test Pictures - Set up bench test of the LR1610 Redesign Heat Exchanger; and (5) Warm Test Data - Warm N2 test data of the LR1610 Redesign Heat Exchanger. Warm test data of the LR1610 Redesign Heat Exchange vs. the warm test data of the two standard LR1610 heat exchangers.

Heat transfer coefficients in a liquid/solid fluidized bed heat exchanger are investigated for application in ice slurry generators. A range of temperature driving forces is determined in which ice slurry generation is stable. In this range ice crystal formation or growth does not affect heat transfer coefficients. A model is proposed that accurately predicts heat transfer coefficients in the fluidized bed ice slurry generator. Due to lower temperatures and higher viscosity in ice slurry generation, heat transfer coefficients measured are lower than predicted with heat transfer correlations specific for liquid/solid fluidized bed heat exchangers. Heat transfer coefficients measured are however significantly higher than for single phase fluid flow. (author)

This patent describes a process of controlling an integrated heat pump system of the type. It comprises a variable speed compressor having a discharge port and a suction port; a water heater exchanger coupled to the discharge port of the compressor for heating water by transfer of heat from a compressed heat exchange fluid; an outdoor evaporator heat exchanger having an outdoor fan and a coil receiving the heat exchange fluid from the water heat exchanger and coupled also to the suction port of the compressor, for drawing heat from the outdoor air which heat is transferred to the water in the water heat exchanger; a controller having output channels to control an outdoor fan and the speed of the variable speed compressor and inputs respectively coupled to a water heater setpoint adjustment means, an outdoor air temperature sensor for sensing the outdoor temperature of the outdoor air; and a water temperature sensor for sensing the temperature of the water heated by the water heat exchanger; the process comprising the steps of sensing the outdoor temperature T{sub o}.

A high temperature heater has been designed and manufactured which is light-weight, compact and capable of obtaining a high heat-generating density in order to be used for a Vuilleumir heat pump that has recently attracted attention as a non-fluorocarbon refrigerator. The structure of this heater was such that a number of perforated heat exchanger plates and spacers were laminated in a heat-resisting metallic heater case and that heater cases for sheath heaters to be inserted were put through in the direction vertical to the heat exchanger plates. The number of laminated sheets of the heat exchanger plates was 50 sheets. An overall heat transfer coefficient was expected to be larger in a heat exchanger by making a perforated plate a heat exchanger plate. The ratio of a heat transfer area over an occupancy volume was 1,000 or more, and the device was classified into a compact heat exchanger. The program NiSA2 under a general finite element method was employed for the structural analysis and the heat transfer analysis. In the verification test of the subject heater, the basic data were collected by the use of air such as temperature rising characteristic, endothermic quantity of the heater, average heat transfer coefficient and pressure loss coefficient, which were shown in agreement with the operational characteristics of the Vuilleumir heat pump. 9 refs., 11 figs., 3 tabs.

the transparent wall and the radiation receiver with minimal heat transfer to and from ... first pass for the inert gas through a double-pass heat exchanger, as shown in figure 1. ..... minimize the pressure differential across wall structures.

and aqueous glycol (30%), require the addition of a heat exchanger. A heat ...... AUTONOMOUS SPACE PROCESSOR FOR ORBITAL DEBRIS REMOVAL. AND .... drical polypropylene canisters for ...... Sand filtration and ultrafiltration remove ...

SCHEMATIC OUTLINE OF PHOT'OFORM GLASS PROCEDURES . . . . . . . . 35 vi ..... y fib. In addition to radiative heat exchange, there is a conducted heat loss between the detec- tor and its .... using ion beam milling thinning techniques.

HEAT EXCHANGER POWER INCREASE POTENTIAL . .... An in-space fission power system is developed by ground-testing, evaluating, and improving ... the flow annuli in the test model, where most of the heat transfer takes place, are ...

control and monitoring center for all Shuttle ground support and launch processing). ... During the ground processing and launch ... of KATE was tested with a scale model of the Environmental ..... The heat exchanger acts as a heat sink for the ...

(traditional technologies use sublimation of water, which ... selective adsorbent that has been cooled via a heat exchanger to ... Adsorption for Carbon Dioxide and Heat Removal/. Rejection in a ... technology is feasible for a PLSS application.

This document summarizes the technological evolution of reversible heat pumps and of their components and emitters since 15 years: compressors, heat exchangers, 4 way valve, pressure reducer, refrigerants, noise pollution, deicing systems, thermoregulation, technological changes, performances evolution. (J.S.)

1 Thermal Systems Engineer, Crew and Thermal Systems Division, Mail Code EC-2. .... the heat acquisition function using various coldplates and heat exchangers, ... The internal loop is driven by a centrifugal pump, and the system flow rate is ...

This experimental work was carried out to obtain basic information on frost melting on a heat exchanger used as a heat pump air conditioner. The heat exchanger working fluid used in this experiment was a 50 wt% propylene glycol aqueous solution. The flow amount G and the temperature T{sub b} of the working fluid were 0.1 {lt} G m{sup 3}/hour {lt} 0.2 and 10 {lt} T{sub b}0{degrees}C {lt} 34, respectively. A melting thermal efficiency {eta} is defined in this paper as the ratio of the net heat for melting to the heat supplied to the heat exchanger until the critical time for melting t{sub c}. {eta} strongly depends on t{sub c}, and t{sub c} is strongly affected by G and T{sub b}. In conclusion, it was found that the heat supplied to the heat exchanger can be utilized with a high {eta} when t{sub c} becomes small.

Deposits encountered in the heat exchanger represented a thermal resistance as high as ...... During cleaning, the heat liberated by the oxidation of a 0.020- cm thick ... same at their respective JFTOT breakpoint temperatures. The breakpoint ...

The objective of this study is to obtain the performance test data for the passive residual heat removal heat exchanger being designed to remove the decay heat with combined effects of the natural circulation of water by means of thermosyphon at the inside and the natural convection of air at the outside. Through the tests, the following results were obtained : (1) The thermosyphon flow between the heater and the finned tubular heat exchanger was smoothly established and flow rates of the thermosyphon were in good agreement with theoretical values. (2) Maximum heat removal rate per unit length of heat exchanger at equilibrium state were measured as 405 W/m for single bundle and 285 W/m for multi-bundle. (3) Natural convective heat transfer coefficients of air at the heat exchanger were ranging from 6 W/m{sup 2} K to 15 W/m{sup 2} K. 35 figs, 2 tabs, 8 refs. (Author).

The non-equilibrium process due to irreversible heat exchanges occurring during a temperature modulated differential scanning calorimetry experiment is investigated in detail. This enables us to define an experimental frequency dependent complex heat capacity from this calorimetric method. The physi...

fluid is heated and vaporized by exchange with the hot water, expanded in a turbine, condensed to a liquid-with a ... These units closely simulate the con-. Some reduction in heat transfer rates has occurred. We believe that an economical ...

significant radiative heating during the atmospheric pass. These large aerobrakes are intended ...... grid line (one zone per grid line); uses block format ...... Influence of Energy. Exchange. Models. d. Thermophys. _4 Heat. 7Yansf., vol . 6, no. 3, ...

Level of Interface. Between. Liquid and Vapor ....... 7. 3. Heat. Pipe Operating. Limits ...... Block. Cooling Coils. Instrument Ports. Figure. 4: Experimental. Rectangular ...... exchange heat. With the environment through conduc4ion, radiation, and ...

The goal of this research program is to understand the phenomenon of soil heat transfer coupled with fluid flow, soil moisture freezing, soil moisture migration, and ground surface temperature variation. From these studies, comprehensive ground coil mathematical models are being developed to better predict ground coil heat exchanger performance. The program has been loosely divided into three phases. Phase I was for ground coils involving heat transfer only, which was suitable for deep-well, tube-in-tube type ground heat exchanger analyses. A mathematical model based on energy balance coupled with fluid flow was solved numerically. The model was validated with laboratory experimental data obtained from a vertical, tube-in-tube heat exchanger 47 m (155 ft) deep. Figure 1 shows the configuration of the heat exchanger. Figure 2 shows the excellent agreement between the calculated and experimental results. The parametric study indicates that the size and material of the exchanger casing and the length of the exchanger are important factors in determining the performance of the ground heat exchanger. Table 1 shows monthly ground coil cooling and heating performance. The ground coil system performs better than an air-source heat pump system in the heating season, but the latter is better for the cooling season. Nevertheless, the ground coil system achieved a respectable annual performance factor of 2.4. We have developed various advanced ground coil models for different types of ground coils and various factors affecting soil heat transfer. 13 refs., 8 figs., 1 tab.