Optimum Design and Operation of Thermoelectric Heat Pump With Two Temperatures

2015 ◽  
Author(s):  
Kazuaki Yazawa ◽  
Ali Shakouri
Keyword(s):  
Power Generation ◽  
Heat Pump ◽  
Constant Temperature ◽  
Temperature Difference ◽  
Heat Sink ◽  
Electronics Cooling ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Impedance Match ◽  
Maximum Heat

We present a comprehensive analysis and optimization of the thermoelectric (TE) heat pump and refrigeration in contact with two constant-temperature reservoirs, followed by a discussion of their cost effectiveness. In many applications in electronics cooling, the heat source temperature is constrained as well as the gas or liquid cooling heat sink. We optimize the thermoelectric design by changing both the element (leg) thickness and drive current simultaneously in order to achieve maximum energy efficiency, i.e., to obtain the highest coefficient of performance (COP) for the heat pump. Each variable and performance is considered per unit area. COP vs cooling capacity, which is the heat amount pumped, by changing the driving current, shows a unique characteristic and it looks like the Greek character ‘beta’ in a plot. This ‘beta plot’ gives a global view of the performance of various TE heat pump systems. We discuss the similarity with the graph obtained in power generation in contact with the constant temperature reservoirs when the trade-off between the efficiency and power output is considered. In this plot, the maximum COP is found at a much smaller current compared to the maximum heat cooling capacity Qmax. This Qmax is found when the internal resistance is sqrt (1 + ZT) times the sum of the external resistances, but only when these contacts are symmetric and the net temperature difference is zero. The ratio increases slightly as the net temperature difference increases (heat pumping to a higher temperature). This shows some differences compared to the power generation mode where an impedance match happens when the ratio of internal to external resistances is constant at sqrt (1 + ZT). If the contact thermal resistances with the hot and cold sides are asymmetric, Qmax and the optimum resistance ratio are both reduced when the heat sink resistance increases and they both increase as the heat sink resistance decreases. TE materials are expensive relative to the other components; hence, it is important to minimize the material use. The COP per cost and cooling capacity per cost are investigated. Similar to power generators, the TE element can be thinner as the fractional area coverage of the TE elements is reduced, while maintaining a constant internal thermal resistance. The most cost effective design is found to be thinner than that of the maximum performance. Also, the ZT value impact for the cost performances is smaller, especially in COP.

Modeling of a Smart Heat Pump Made of Laminated Thermoelectric and Electrocaloric Materials

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Dudong Feng ◽  
Shi-Chune Yao ◽  
Tian Zhang ◽  
Qiming Zhang
Keyword(s):  
Heat Pump ◽  
Temperature Difference ◽  
Coefficient Of Performance ◽  
Pump System ◽  
Laminated Structure ◽  
Heat Pump System ◽  
Simple Arrangement ◽  
Parametric Effects ◽  
Hybrid Heat Pump ◽  
Physical Features

In this study, a smart heat pump, which could be used for the cooling of electronics, made of laminated structure of thermoelectric (TE) and electrocaloric (EC) materials, is studied. A simple arrangement of two TE layers sandwiched with one EC layer is modeled. This smart heat pump utilized the newly developed EC materials of giant adiabatic temperature change and the TE materials of high figure of merit. The system has the advantages of no moving parts, made of solid state, operable over large working temperature difference, and can be formed into very small size. The operation of the device is numerically modeled considering the three major parametric effects: EC operation as a function of time, electric current applied on TE, and temperature difference between the hot and cold sinks. The results on coefficient of performance (COP) and heat flow per unit area are discussed. This study is performed as an early attempt of analyzing the basic physical features of TE–EC–TE laminated structure heat pump and extends the understanding by further discussing the tradeoff between lower COP and larger overall temperature difference coverage in the TE/EC hybrid heat pump system with multilaminated structure.

Two-Stage Non-Regenerative Silica Gel-Water Adsorption Refrigeration Cycle

2000 ◽  
Author(s):  
B. B. Saha ◽  
K. C. A. Alam ◽  
A. Akisawa ◽  
T. Kashiwagi ◽  
K. C. Ng ◽  
...  
Keyword(s):  
Heat Pump ◽  
Silica Gel ◽  
Water Adsorption ◽  
Waste Heat ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Adsorption Refrigeration ◽  
Two Stage ◽  
Adsorption Chiller ◽  
Adsorption Heat Pump

Abstract Over the past two decades there have been considerable efforts to use adsorption (solid/vapor) for cooling and heat pump applications, but intensified efforts were initiated only since the imposition of international restrictions on the production and use of CFCs (chlorofluorocarbons) and HCFCs (hydrochlorofluorocarbons). Closed-type, conventional adsorption refrigeration and heat pump systems have an increasing market share in Japan. In this paper, a two-stage non-regenerative, silica gel-water adsorption chiller design is outlined. Experimental measurements are performed on a prototype of a 3.5 kW rated cooling capacity adsorption heat pump in order to determine its performance under different operating temperatures (hot, cooling and chilled water). The chiller performance is analyzed in terms of cooling capacity and coefficient of performance (COP). The main innovative feature in the two-stage adsorption chiller is the ability to utilize low-temperature waste heat (∼55°C) as the driving source with a cooling source of 30°C. The technological difficulty inherent in operating a thermally activated cycle with such a small regenerating temperature lift (temperature difference between heat source and heat sink inlets) is overcome by use of a two-stage cycle.

Thermal Performance of Microchannels With Dimples for Electronics Cooling

2013 ◽  
Author(s):  
Hui Lu ◽  
Liang Gong ◽  
Minghai Xu
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Integrated Circuits ◽  
Heat Sink ◽  
Electronics Cooling ◽  
Cooling Capacity ◽  
Constant Heat Flux ◽  
Microchannel Heat Sink ◽  
Transfer Enhancement ◽  
Different Types

The thermal management of integrated circuits becomes more and more serious since the density of transistors grows gradually. Recently, a new cooling method is dedicated to develop microchannel heat sink with high integrated and high cooling efficiency. In view of above purpose, the heat transfer enhancement and pressure drop reduction in microchannel with dimples are investigated in this paper. A single module of 1mm×1mm×20mm with a microchannel was employed, which hydraulic diameter and aspect ratio are 500 μm and 2:1 respectively. For replacing the running integrated circuits, a constant heat flux of 1W/mm2 was arranged on the bottom of the heat sink. Six different types of microchannels with dimples were designed and numerically studied under the condition of laminar flow. The results show that dimple could enhance heat transfer and decrease flow resistance under the condition of laminar flow. Compared with traditional microchannel heat sink, dimple-microchannel heat sink has stronger cooling capacity, could be an attractive choice for cooling of future microelectronics.

scholarly journals An experimental investigation on the performance of a thermoelectric dehumidification system

2018 ◽  
Vol 12 (4) ◽  
pp. 4117-4126
Author(s):  
P. Rakkwamsuk ◽  
P. Paromupatham ◽  
K. Sathapornprasath ◽  
C. Lertsatitthanakorn ◽  
S. Soponronnarit
Keyword(s):  
Heat Sink ◽  
Cooling System ◽  
Test Chamber ◽  
Cooling Water ◽  
Suitable Condition ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Air Cooling ◽  
Air Cooling System ◽  
Te Modules

A thermoelectric (TE) air-cooling system for dehumidifying indoor air in a building was investigated. The system was composed of 4 TE modules. The cold sides of the TE modules were fixed to an aluminum heat sink to remove moisture in the air of a test chamber of 1 m3 volume, while a heat sink with circulating cooling water at the hot sides of the TE modules was used for heat release. The effects of input electric current to the TE modules and air flow rate through the heat sink were experimentally determined. The system’s performance was evaluated using dehumidification effectiveness and coefficient of performance (COP). A suitable condition occurred at 18.5 A of current flow and 240 W of power being supplied to the TE modules with a corresponding cooling capacity of 149.5 W, which gave a dehumidification effectiveness of 0.62. Therefore, it is anticipated the proposed TE dehumidifier concept will contribute to the air conditioning system’s reduction of room humidity. 

Improvement of Thermal Performance of Pin Fin Heat Sink Using Different Types of Perforations: A Study Under Natural Convection

2019 ◽  
Author(s):  
Aashish Kumar ◽  
Manoj Kumar Mondal
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Heat Sink ◽  
Transfer Rate ◽  
Coefficient Of Performance ◽  
Reduced Pressure ◽  
Maximum Heat ◽  
Transfer Rates ◽  
Pin Fin ◽  
Maximum Heat Transfer

Abstract Improvement of thermal management can significantly enhance the coefficient of performance (COP) of the thermoelectric (TE) system which is one of the potential solutions for cooling electronic components. Since heat sinks are an integral part of all the electronic equipment, therefore, great consideration is given towards meticulous selection of heat sink for improving its reliability and performance. Various methods are being studied to improve heat transfer rates of heat sink such as microchannel, liquid cooling, nano-fluids, fin topology optimization, anodization of pins, and changing heat sink materials. Recent studies have demonstrated that perforations in pins increase the heat transfer rate of pin fin heat sink, though, the results are inadequate to infer the best geometry. Further research is hence necessary to establish the best possible combination of geometry, size, and number of perforations. The present work aims to numerically identify a heat sink configuration with maximum heat transfer rate among several configuration possibilities under laminar flow condition using ANSYS Fluent 18.2. The simulation results demonstrate that lateral perforation in fins enable higher heat transfer rate than the unmodified heat sink geometry, due to higher Nusselt number and reduced pressure drop. The parametric study also reveals that heat sink with three elliptical perforations boost heat transfer rates (about 21% higher) when compared to heat sink with solid and other perforated geometries. Furthermore, perforations reduce weight and greater effectiveness, making it more desirable for its wide-scale applications.

Design and Performance of a Constant Temperature and Humidity Air-Conditioning System Driven by a Ground Source Heat Pump in Summer

2010 ◽  
Vol 2 (1) ◽  
Author(s):  
X. Yu ◽  
X. Q. Zhai ◽  
R. Z. Wang
Keyword(s):  
Heat Pump ◽  
Constant Temperature ◽  
Air Conditioning ◽  
Weather Condition ◽  
Coefficient Of Performance ◽  
Heat Extraction ◽  
Ground Source Heat Pump ◽  
Air Conditioning System ◽  
Ground Source ◽  
Temperature And Humidity

A constant temperature and humidity air-conditioning system driven by a ground source heat pump was designed and constructed in an archives building in Shanghai. The system consists of a water-to-water heat pump and 280 boreholes with 80 m in depth. During the operation in summer, the heat extraction from the condenser of the heat pump was divided: Part was rejected to the soil, while another was used to reheat the air in air handling units (AHUs). According to the experimental results under a typical summer weather condition of Shanghai, the average coefficient of performance of the heat pump was 5.4. The average indoor temperature and relative humidity of the archives house were 22.8°C and 46.6%, respectively. Since part of the heat extraction from the condenser was used to reheat the air in AHUs, the heat rejected to the soil was reduced by 23%, which was helpful for the earth energy conservation. According to the theoretical analysis, the distance between two boreholes is suggested to be 4–5 m. The deepness of the boreholes is suggested to be 80–100 m in Shanghai.

Coefficient of Performance of Thermoelectric Cooling on Nanofluids

2013 ◽  
Vol 459 ◽  
pp. 91-99
Author(s):  
Somchai Maneewan ◽  
Atthakorn Thongtha ◽  
Chantana Punlek
Keyword(s):  
Heat Exchanger ◽  
Ethylene Glycol ◽  
Heat Sink ◽  
Cooling System ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Cold Side ◽  
Input Condition ◽  
Current Input ◽  
Experimental Comparisons

This paper reports on experimental comparisons of coefficient of performance (COP) of a thermoelectric coolingsystem which cooled the hot side of the TEC by water (wc), ethylene glycol (egc) and nanofluids (nfc) The nanofluids is composed of ethylene glycol with silver nano(35 nm).The TEC was composed of the TE cooling modules, heat exchanger, and the air cooled heat sink at the cold side of the TE modules.Experiments were conducted with various current input 1 - 4.5 A to find out the optimum current input condition. To consideration of cooling capacity and COP of system was measured the hot and cold side temperature of TEC. Results shown that, the cooling capacity was increased with current input. The maximum cooling capacity of nfc, egc and wc are about 72, 62 and 41 W, respectively. Considered with highest COP found that the optimum current input is approximately 2.5 A. The maximum COP of nfc, egc and wc are about 2.01, 1.7 and 1.12, respectively. Therefore, the proposed TEC-nfc concept is expected to contribute to wider applications of the TE cooling system.

Comparison of Performance between R290 and R417A in Heat Pump Air Conditioning Water Heater Combination

2011 ◽  
Vol 243-249 ◽  
pp. 4918-4922
Author(s):  
Jian Bo Chen ◽  
Kuang Wei Min ◽  
Fen Li
Keyword(s):  
Water Temperature ◽  
Heat Pump ◽  
Air Conditioning ◽  
Power Input ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Water Heater ◽  
Discharge Temperature ◽  
Natural Refrigerant ◽  
Discharge Pressure

The natural refrigerant R29O and mixed refrigerant R417A is currently approved ideal substitutes of R22, The performance of R290 and R410A in the same heat pump air conditioning water heater combination was studied experimentally, heating capacity, cooling capacity, power input, COP ,discharge pressure, suction pressure,discharge temperature were measured, the performance of heat pump air conditioning water heater combination at standard air condition and varied inlet-water temperature was analyzed .The results show that the most appropriate charge mass of R290 is only 52% of R417A in the same systems ,so using r290 more environmentally friendly.The coefficient of performance (COP) is higher than R417A in the same capacity, so using r290 have lower energy consumption, more energy-saving. Compressor discharge pressure and temperatures of R290 is lower than R417A in the same inlet-water temperature, so using r290 favors the system security operation. But the performance of R290 influenced by the inlet water temperature more obvious than R417A, it's not very suitable for the occasion of high inlet-water temperature.

scholarly journals Experimental analysis of a continuous operating ground source heat pump system in Wuhan, China

2018 ◽  
Vol 22 (Suppl. 2) ◽  
pp. 491-496
Author(s):  
Qianjun Mao ◽  
Yufeng Chen ◽  
Suisui Jin ◽  
Lei Shi ◽  
Liangli Xiao
Keyword(s):  
Heat Pump ◽  
Atmospheric Temperature ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Testing Time ◽  
Ground Source Heat Pump ◽  
Pump System ◽  
Heat Pump System ◽  
Average Value ◽  
Ground Source

Coefficient of performance of air conditioning system is the ratio of cooling capacity and power consumption, and also is an important parameter to characterize the performance of the system. Based on an actual ground source heat pump system in Wuhan, China, this paper calculated the coefficient of performance of the system under long-term continuous cooling operation and then evaluated the performance of the system through experiment. The continuous testing time ranged from June 1, 2017, to June 15, 2017, and the outside air temperature ranged from 21?C to 32?C during the testing progress. The experimental results show that the coefficient of performance of the system changes non-linearly with time, and varies greatly with the atmospheric temperature. The results also show that the coefficient of performances average value of the system is about 3.3, and the system has good performance under refrigeration conditions. This paper helps to understand the changes in the distribution characteristics of the coefficient of performance of the ground source heat pump system and promote the wide application of the ground source heat pump system.

scholarly journals Investigation of the Environmentally-Friendly Refrigerant R152a for Air Conditioning Purposes

2018 ◽  
Vol 9 (1) ◽  
pp. 119 ◽  
Author(s):  
Evangelos Bellos ◽  
Christos Tzivanidis
Keyword(s):  
Heat Pump ◽  
High Performance ◽  
Environmentally Friendly ◽  
Cooling Capacity ◽  
Heat Pumps ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Cooling Systems ◽  
Detailed Model ◽  
Ambient Temperatures

Heat pumps are efficient and well-established technologies for providing the proper cooling load in the building sector. The objective of this work is the parametric investigation of a heat pump operating with the promising refrigerant R152a for different operating conditions. More specifically, the heat pump is studied for different ambient temperatures, different indoor temperatures and various compressor rotational speeds. The cooling capacity and the coefficient of performance (COP) are the most important parameters which calculated in every scenario. A detailed model is developed in Engineering Equations Solver (EES) and it is validated with literature data. According to the final results, the system can operate in nominal conditions with 5 kW cooling capacity and a COP equal to 6.46. It is found that the COP can be ranged from 4 to 12 and the cooling capacity, while the cooling capacity can reach up to 9 kW. Moreover, a regression equation about the performance of the system is suggested. The obtained results indicate that the use of the R152a leads to high performance and so it can be an environmentally friendly choice for the cooling systems.

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