Advanced Heat Exchange Technology for Thermoelectric Cooling Devices

1998 ◽  
Vol 120 (1) ◽  
pp. 98-105 ◽  
Author(s):  
R. L. Webb ◽  
M. D. Gilley ◽  
V. Zarnescu
Keyword(s):  
Heat Exchanger ◽  
Heat Exchange ◽  
High Performance ◽  
Operating Conditions ◽  
Heat Sources ◽  
Thermoelectric Coolers ◽  
Heat Exchanger Design ◽  
Cooling Devices ◽  
Conventional Technology ◽  
Current Heat

Thermoelectric coolers (TEC) are potentially ideal devices to cool electronic components or small electronic enclosures. However, practical heat exchange can limit the COP and restrict the range of useful applications. The TEC must reject heat from the hot side to the ambient, which is typically air. The COP can be increased by reducing the hot-side temperature, which requires a high-performance heat exchanger. An understanding of the heat sources in the TEC is presented, and relations are presented to define the hot-side thermal resistance required to operate at desired operating conditions. A novel air-cooled thermosyphon reboiler-condenser system has been developed that promises significantly higher COP for thermoelectric coolers than is possible with current heat exchange technology. This heat exchanger design concept is described and compared to conventional technology.

Development of New Heat Exchanger Design

2011 ◽  
Author(s):  
Anthony Couzinet ◽  
Daniel Pierrat ◽  
Laurent Gros ◽  
Thierry Kunc ◽  
Antoine Foata
Keyword(s):  
Heat Exchanger ◽  
Operating Conditions ◽  
Temperature Gradients ◽  
Computational Grids ◽  
Computational Time ◽  
Test Rig ◽  
Heat Exchanger Design ◽  
Numerical Predictions ◽  
Tube Banks ◽  
Heat Transfers

This study deals with a new heat exchanger design developed by DGA Essais propulseurs [inventor: A. Foata - patents 1–4] which should improve heat transfer compared with standard gas to liquid exchangers tube banks, present better compactness without weighing down the drop loss and ensure the behaviour under drastic operating conditions (1600°C and Mach 2). This new design is based on a bundle composed of nine pairs of spiral tubes which are one to one angular drifted. The predictions of the thermal performances are so fussy whatsoever by using experimental test rig or CFD computations. On one hand, the test rig doesn’t allow to fulfil the entire range of operating conditions. And yet the standard operating conditions can shade the influence of temperature gradients on the aero thermal behaviour of the spiral bundles. On the other hand, in order to obtain reliable numerical predictions of heat transfers, the spiral bundle meshing refinement is crucial to simulate accurately the flow structure and the temperature gradients close to the inner walls. Moreover, if the grooves are explicitly taken into account in the numerical model, the computational grids required will be too fine to guarantee realistic computational time. So firstly, experimental and numerical approaches are used jointly in order to show the new heat exchanger design is sustainable. Optimization of the heat exchanger will be performed in the next phase of this study.

Heat Exchanger Design of Direct Evaporative Cooler Based on Outdoor and Indoor Environmental Conditions

2014 ◽  
Vol 6 (4) ◽  
Author(s):  
Neda Gilani ◽  
Amin Haghighi Poshtiri
Keyword(s):  
Heat Exchanger ◽  
Thermal Comfort ◽  
Indoor Air ◽  
Ambient Air ◽  
Operating Conditions ◽  
Design Guideline ◽  
Heat Exchanger Design ◽  
Evaporative Cooler ◽  
Direct Evaporative Cooler ◽  
Comfort Criteria

Performance of a direct evaporative cooler (DEC) was numerically studied at various outdoor and indoor air conditions, with geometric and physical characteristics of it being extracted based on thermal comfort criteria. For this purpose, a mathematical model was utilized based on the equations of mass, momentum, and energy conservation to determine heat and mass transfer characteristics of the system. It is found that the DEC can provide thermal comfort conditions when the outdoor air temperature and relative humidity (RH) are in the range of 27–41 °C and 10–60%, respectively. The findings also revealed that by raising the RH of ambient air, the system will reach the maximum allowed RH faster and hence a smaller heat exchanger can be used when the ambient air has higher RH. Finally, performance of the DEC in a central province of Iran was investigated, and a design guideline was proposed to determine size of the required plate heat exchangers at various operating conditions.

scholarly journals Gas-to-gas heat exchanger design for high performance thermal energy storage

2017 ◽  
Vol 14 ◽  
pp. 311-321 ◽  
Author(s):  
B. Cárdenas ◽  
S.D. Garvey ◽  
B. Kantharaj ◽  
M.C. Simpson
Keyword(s):  
Energy Storage ◽  
Heat Exchanger ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
High Performance ◽  
Heat Exchanger Design

Estimating ASME Section III and VIII Heat Exchanger Nozzle Loads

2009 ◽  
Author(s):  
L. Ike Ezekoye ◽  
Colin Arnold
Keyword(s):  
Heat Exchanger ◽  
Heat Exchange ◽  
Power Plant ◽  
Material Properties ◽  
Heat Exchangers ◽  
Operating Conditions ◽  
Design Criteria ◽  
Physical Geometry ◽  
External Forces ◽  
Stress Criteria

Heat Exchange Institute (HEI) Standards for Power Plant Heat Exchangers, 4th Edition provides guidance on how to estimate the nozzle loads of cylindrical shells. The procedure covered in one of the appendices of the document relies on WRC Bulletin 107 methodology which uses internal pressure, physical geometry and material properties to estimate external forces and moments. The forces and moments are the limiting loads when the heat exchanger material is taken to yield. The material yield defines the range of possible load combinations that will meet the design criteria. However, for operability, the design criteria sometimes may differ from the yield but usually is based on heat exchanger supplier experience. This paper provides a way to estimate heat exchanger nozzle loads that more closely reflect operating conditions that take into account supplier experience. In this paper, generalized load formulae are developed for the nozzles. The formulae are iteratively solved to meet the stress criteria based on supplier experience. The resultant loads are evaluated using WRC Bulletin 107 to ensure that the loads are bounded by the acceptance criteria. Unbounded loads are rejected and reiterated until the loads are acceptable.

Optimization of the Fin-and-Tube Heat Exchanger Design for Non-Standard Applications

2010 ◽  
Author(s):  
Janybek Orozaliev ◽  
Christian Budig ◽  
Klaus Vajen
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Optimization Procedure ◽  
Operating Conditions ◽  
Genetic Optimization ◽  
Tube Heat Exchanger ◽  
Heat Exchanger Design ◽  
Standard Application ◽  
Friction Performance ◽  
Genetic Optimization Algorithm

This paper describes an optimization procedure of the heat exchanger design, which is based on cost effectiveness. In the procedure, a genetic optimization algorithm varies the heat exchanger geometry and operating conditions. The influence of the heat exchanger design on its costs, heat transfer and friction performance has been evaluated economically by determining investment and operation costs of the system. For this purpose, a specific approach for setting up of cost functions of the heat exchanger, fans and pumps is presented as well. It has been shown on a non-standard application, that the heat transfer costs of the optimized heat exchanger design is 30% lower than that of the reference configuration, which was designed by a heat exchanger producer.

Performance Evaluation of Dynamic Model of Compact Heat Exchange Reformer for High-Temperature Fuel Cell Systems

2013 ◽  
Vol 11 (1) ◽  
Author(s):  
Jeongpill Ki ◽  
Daejong Kim
Keyword(s):  
Steady State ◽  
Heat Exchanger ◽  
Fuel Cell ◽  
Heat Exchange ◽  
Dynamic Model ◽  
Operating Conditions ◽  
Transfer Model ◽  
Thermal Dynamics ◽  
Internal Reforming ◽  
Experimental Apparatus

Solid oxide fuel cell (SOFC) systems are the most advanced power generation system with the highest thermal efficiency. The current trend of research on the SOFC systems is focused on multikilowatt scale systems, which require either internal reforming within the stack or a compact external reformer. Even if the internal reforming within the SOFC stack allows compact system configuration, it causes significant and complicated temperature gradients within the stack, due to endothermic reforming reactions and exothermic electrochemical reactions. As an alternative solution to the internal reforming, an external compact heat exchange reformer (CHER) is investigated in this work. The CHER is based on a typical plate-fin counterflow or coflow heat exchanger platform, and it can save space without causing large thermal stress and degradation to the SOFC stack (i.e., eventually reducing the overall system cost). In this work, a previously developed transient dynamic model of the CHER is validated by experiments. An experimental apparatus, which comprises the CHER, air heater, gas heater, steam generator, several mass flow controllers, and controller cabinet, was designed to investigate steady state reforming performance of the CHER for various hot air inlet temperatures (thermal energy source) and steam to carbon ratios (SCRs). The transient thermal dynamics of the CHER was also measured and compared with simulations when the CHER is used as a heat exchanger with inert gas. The measured transient dynamics of CHER matches very well with simulations, validating the heat transfer model within the CHER. The measured molar fractions of reformate gases at steady state also agree well with the simulations validating the used reaction kinetics. The transient CHER model can be easily integrated into a total integrated SOFC system, and the model can be also used for optimal design of similar CHERs and provides a guideline to select optimal operating conditions of the CHERs and the integrated SOFC system.

Development of a Ceramic Heat Exchanger for Application as Solid Oxide Fuel Cell Cathode Air Preheater

2016 ◽  
Author(s):  
José Luis Córdova ◽  
Hooshang Heshmat
Keyword(s):  
Heat Exchanger ◽  
Fuel Cell ◽  
Heat Exchange ◽  
Pressure Drop ◽  
Solid Oxide Fuel Cell ◽  
Ceramic Material ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Air Preheater

A ceramic heat exchanger with high effectiveness and low-pressure drop is being developed for application as a cathode air preheater for a Solid Oxide Fuel Cell (SOFC). At the operating conditions of SOFCs, typical metallic alloys as those used in commercial heat exchangers may undergo chromium volatilization, which is a known cathode degradation mechanism that reduces SOFC performance and life. Use of ceramics such as alumina or alumina-silicate instead of chromium-containing metal is one approach to eliminate the effects of chromium on the SOFC cathode. This project leverages the geometric design of a heat exchanger previously prototyped and tested, and demonstrated to have a nearly constant heat transfer effectiveness of 92% with low pressure drop [1], to fabricate a novel heat exchanger made from a ceramic material. This paper calculates heat exchanger performance requirements based on state of the art SOFC operating conditions, presents a thermal-based tradeoff analysis for ceramic material selection, and presents a modular heat exchanger and its heat exchange elements. The modular concept presented allows for incremental aggregation of modules to target a broad range of operating conditions typical of present and upcoming SOFC applications (e.g., 25 to 400 kWe). A fabricated sample ceramic heat exchange element is shown to demonstrate the viability of the concept for a real SOFC application.

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