Heat transfer effect on optimal performance of two-stage thermoelectric heat pumps

2007 ◽  
Vol 221 (12) ◽  
pp. 1635-1641 ◽  
Author(s):  
L Chen ◽  
J Li ◽  
F Sun
Keyword(s):  
Heat Transfer ◽  
Heat Pump ◽  
Analytical Formula ◽  
Electrical Current ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Two Stage ◽  
Thermo Electric ◽  
Heating Load ◽  
Thermoelectric Heat

A model of two-stage semiconductor thermoelectric heat pumps with external heat transfer and internal irreversibility is built. Performance of the heat pump with Newton's heat transfer law is analysed and optimized using the combination of finite-time thermodynamics and non-equilibrium thermodynamics. The analytical formula about heating load versus working electrical current, and the coefficient of performance (COP) versus working electrical current are derived. For the fixed total number of thermoelectric elements, the ratio of number of thermo-electric elements of top stage to the total number of thermoelectric elements is also optimized for maximizing the heating load and the COP of the thermoelectric heat pump. The effects of design factors on the performance are analysed.

scholarly journals Modeling the Performance of Water-Zeolite 13X Adsorption Heat Pump

2017 ◽  
Vol 38 (4) ◽  
pp. 191-207 ◽  
Author(s):  
Kinga Kowalska ◽  
Bogdan Ambrożek
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Heat Pump ◽  
Heat Pumps ◽  
Adsorption Heat ◽  
Coefficient Of Performance ◽  
Desorption Kinetics ◽  
Zeolite 13X ◽  
Adsorption Heat Pump

Abstract The dynamic performance of cylindrical double-tube adsorption heat pump is numerically analysed using a non-equilibrium model, which takes into account both heat and mass transfer processes. The model includes conservation equations for: heat transfer in heating/cooling fluids, heat transfer in the metal tube, and heat and mass transfer in the adsorbent. The mathematical model is numerically solved using the method of lines. Numerical simulations are performed for the system water-zeolite 13X, chosen as the working pair. The effect of the evaporator and condenser temperatures on the adsorption and desorption kinetics is examined. The results of the numerical investigation show that both of these parameters have a significant effect on the adsorption heat pump performance. Based on computer simulation results, the values of the coefficients of performance for heating and cooling are calculated. The results show that adsorption heat pumps have relatively low efficiency compared to other heat pumps. The value of the coefficient of performance for heating is higher than for cooling

Cooling and heating rate limits of a reversed reciprocating ericsson cycle at steady state

2000 ◽  
Vol 214 (1) ◽  
pp. 75-85 ◽  
Author(s):  
D A Blank ◽  
C Wu
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Heat Pump ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Design Parameters ◽  
Optimized Design ◽  
Cooling Mode ◽  
Working Fluids ◽  
Heating And Cooling

The optimal cooling and heating rates for the reversed reciprocating Ericsson cycle with ideal regeneration are determined for heat pump operations. These limiting rates are based on the upper and lower thermal reservoir temperature bounds and are obtained using time and entropy minimization procedures from irreversible thermodynamics. Use is made of time symmetry (a second law constraint) to minimize cycle time. This optimally allocates the thermal capacitances of the cycle and minimizes internal cycle entropy generation. Although primarily a theoretical work, a very practical and extensive parametric study using several environmentally friendly working fluids (neon, nitrogen and helium) is included. This study evaluates the relative contributions of various system parameters to rate-optimized design. The coefficient of performance (COP), and thus the quantity of cooling or heating for a given energy input, is the traditional focus; instead this work aims at the rate of cooling or heating in heat pumps under steady state conditions and using ideal gases as their working substances. The results obtained provide additional criteria for use in the study, design and performance evaluation of employing Ericsson cycles in refrigeration, air conditioning and heat pump applications. They give direct insight into what is required in designing a reversed Ericsson heat pump to achieve maximum heating and cooling rates. The choices of working fluids and pressure ratios were found to be very significant design parameters, together with selection of regenerator and source—sink heat transfer parameters. The parameter most influencing both the heating and cooling mode COPs and the heat transfer rates was found to be the heat conductance of the thermal sink.

Finite-Time Thermodynamic Performance for a Class of Irreversible Heat Pumps

1997 ◽  
Author(s):  
Chih Wu ◽  
Lingen Chen ◽  
Fengrui Sun
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Heat Pump ◽  
Finite Time ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Cooling Load ◽  
Heat Leak ◽  
Thermodynamic Performance ◽  
The Relationship

The effect of heat resistance and heat leak on the performance of irreversible heat pumps using a generalized heat transfer law is analyzed in this paper. The relationship between the optimal cooling load and the cop (coefficient of performance) for a steady-state irreversible heat pump is derived.

TECHNOLOGY REVIEW OF TWO-STAGE VAPOR COMPRESSION HEAT PUMP SYSTEM

2013 ◽  
Vol 21 (03) ◽  
pp. 1330002 ◽  
Author(s):  
KOJO ATTA AIKINS ◽  
SANG-HYEOK LEE ◽  
JONG MIN CHOI
Keyword(s):  
Heat Pump ◽  
High Efficiency ◽  
Industrial Applications ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Two Stage ◽  
Pump System ◽  
Heat Pump System ◽  
Discharge Temperature ◽  
Increasing Demand

There is increasing demand for domestic and industrial refrigeration, space heating and air conditioning. Heat pump systems offer economical alternatives for recovering heat from different sources for use in these applications. As a renewable energy technology for sustainable environment, the heat pump's high efficiency and low environmental impact have already drawn a fair amount of attention all over the world. Some of these domestic and industrial applications require very low evaporating temperatures and very high condensing temperatures which induce high compressor pressure ratios beyond the practical range for single-stage heat pump cycles. These high pressure ratios also produce low coefficient of performance (COP) values and expose the compressor to high discharge temperature, low volumetric efficiency and damage. However, this challenge can be overcome by adopting two-stage heat pump cycles. In this paper, recent works on two-stage heat pump systems for various applications are reviewed. They include two-stage cycle with intercooling, two-stage cycle with refrigerant injection and two-stage cascade cycle. Research and innovative designs of systems that make use of these two-stage cycles have been able to get heat pumps to handle applications with lower and higher temperatures, while enhancing heating capacity up to 30% and COP up to 31%.

scholarly journals Development and Validation of Air-to-Water Heat Pump Model for Greenhouse Heating

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4714
Author(s):  
Adnan Rasheed ◽  
Wook Ho Na ◽  
Jong Won Lee ◽  
Hyeon Tae Kim ◽  
Hyun Woo Lee
Keyword(s):  
Heat Pump ◽  
Storage Tank ◽  
Energy Requirement ◽  
Water Storage ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Water Storage Tank ◽  
National University ◽  
Heating Load ◽  
Development And Validation

This study proposes a building energy simulation (BES) model of an air-to-water heat pump (AWHP) system integrated with a multi-span greenhouse using the TRNSYS-18 program. The proposed BES model was validated using an experimental AWHP and a multi-span greenhouse installed in Kyungpook National University, Daegu, South Korea (latitude 35.53° N, longitude 128.36° E, elevation 48 m). Three AWHPs and a water storage tank were used to fulfill the heat energy requirement of the three-span greenhouse with 391.6 m2 of floor area. The model was validated by comparing the following experimental and simulated results, namely, the internal greenhouse temperature, the heating load of the greenhouse, heat supply from the water storage tank to the greenhouse, heat pumps’ output water temperature, power used by the heat pumps, coefficient of performance (COP) of the heat pump, and water storage tank temperature. The BES model’s performance was evaluated by calculating the root mean square error (RMSE) and the Nash–Sutcliffe efficiency (NSE) coefficient of validation results. The overall results correlated well with the experimental and simulated results and encouraged adopting the BES model. The average calculated COP of the AWHP was 2.2 when the outside temperature was as low as −13 °C. The proposed model was designed simply, and detailed information of each step is provided to make it easy to use for engineers, researchers, and consultants.

Technical Note. Influence of Material Used for the Regenerator on the Properties of a Thermoacoustic Heat Pump

2013 ◽  
Vol 38 (4) ◽  
pp. 565-570 ◽  
Author(s):  
Bartłomiej Kruk
Keyword(s):  
Heat Transfer ◽  
Temperature Gradient ◽  
Acoustic Wave ◽  
Heat Pump ◽  
Sound Wave ◽  
Heat Exchangers ◽  
Heat Pumps ◽  
Technical Note ◽  
New Materials ◽  
Modern Technologies

Abstract Research in termoacoustics began with the observation of the heat transfer between gas and solids. Using this interaction the intense sound wave could be applied to create engines and heat pumps. The most important part of thermoacoustic devices is a regenerator, where press of conversion of sound energy into thermal or vice versa takes place. In a heat pump the acoustic wave produces the temperature difference at the two ends of the regenerator. The aim of the paper is to find the influence of the material used for the construction of a regenerator on the properties of a thermoacoustic heat pump. Modern technologies allow us to create new materials with physical properties necessary to increase the temperature gradient on the heat exchangers. The aim of this paper is to create a regenerator which strongly improves the efficiency of the heat pump.

scholarly journals Heat Pump Bridge Analysis Using the Modified Energy Transfer Diagram

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 137
Author(s):  
Florian Schlosser ◽  
Heinrich Wiebe ◽  
Timothy G. Walmsley ◽  
Martin J. Atkins ◽  
Michael R. W. Walmsley ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Heat Pump ◽  
Heat Recovery ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Combined Application ◽  
Recovery Potential ◽  
Composite Curve ◽  
And Performance ◽  
The Individual

Heat pumps are the key technology to decarbonise thermal processes by upgrading industrial surplus heat using renewable electricity. Existing insight-based integration methods refer to the idealised Grand Composite Curve requiring the full exploitation of heat recovery potential but leave the question of how to deal with technical or economic limitations unanswered. In this work, a novel Heat Pump Bridge Analysis (HPBA) is introduced for practically targeting technical and economic heat pump potential by applying Coefficient of Performance curves into the Modified Energy Transfer Diagram (METD). Removing cross-Pinch violations and operating heat exchangers at minimum approach temperatures by combined application of Bridge Analysis increases the heat recovery rate and reduce the temperature lift to be pumped at the same time. The insight-based METD allows the individual matching of heat surpluses and deficits of individual streams with the capabilities and performance of different market-available heat pump concepts. For an illustrative example, the presented modifications based on HPBA increase the economically viable share of the technical heat pump potential from 61% to 79%.

scholarly journals Factors Shaping A/W Heat Pumps CO₂ Emissions—Evidence from Poland

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1576
Author(s):  
Piotr Jadwiszczak ◽  
Jakub Jurasz ◽  
Bartosz Kaźmierczak ◽  
Elżbieta Niemierka ◽  
Wandong Zheng
Keyword(s):  
Air Quality ◽  
Power System ◽  
Heat Pump ◽  
Heat Pumps ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Conventional Heating ◽  
Additional Stress ◽  
The European Union ◽  
Energy Mix

Heating and cooling sectors contribute to approximately 50% of energy consumption in the European Union. Considering the fact that heating is mostly based on fossil fuels, it is then evident that its decarbonization is one of the crucial tasks for achieving climate change prevention goals. At the same time, electricity sectors across the globe are undergoing a rapid transformation in order to accommodate the growing capacities of non-dispatchable solar and wind generators. One of the proposed solutions to achieve heating sector decarbonization and non-dispatchable generators power system integration is sector coupling, where heat pumps are perceived as a perfect fit. Air source heat pumps enable a rapid improvement in local air quality by replacing conventional heating sources, but at the same time, they put additional stress on the power system. The emissions associated with heat pump operation are a combination of power system energy mix, weather conditions and heat pump technology. Taking the above into consideration, this paper presents an approach to estimate which of the mentioned factors has the highest impact on heat pump emissions. Due to low air quality during the heating season, undergoing a power system transformation (with a relatively low share of renewables) in a case study located in Poland is considered. The results of the conducted analysis revealed that for a scenario where an air-to-water (A/W) heat pump is supposed to cover space and domestic hot water load, its CO2 emissions are shaped by country-specific energy mix (55.2%), heat pump technology (coefficient of performance) (33.9%) and, to a lesser extent, by changing climate (10.9%). The outcome of this paper can be used by policy makers in designing decarbonization strategies and funding distribution.

scholarly journals Heat pump systems: A mini review

2021 ◽  
Vol 4 (2) ◽  
pp. 73-81
Author(s):  
Mohammad Omar Temori ◽  
František Vranay
Keyword(s):  
Heat Pump ◽  
Electricity Consumption ◽  
Cost Savings ◽  
Electrical Energy ◽  
Primary Energy ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Heating And Cooling ◽  
Ground Source ◽  
Reduce Electricity Consumption

In this work, a mini review of heat pumps is presented. The work is intended to introduce a technology that can be used to income energy from the natural environment and thus reduce electricity consumption for heating and cooling. A heat pump is a mechanical device that transfers heat from one environmental compartment to another, typically against a temperature gradient (i.e. from cool to hot). In order to do this, an energy input is required: this may be mechanical, electrical or thermal energy. In most modern heat pumps, electrical energy powers a compressor, which drives a compression - expansion cycle of refrigerant fluid between two heat exchanges: a cold evaporator and a warm condenser. The efficiency or coefficient of performance (COP), of a heat pump is defined as the thermal output divided by the primary energy (electricity) input. The COP decreases as the temperature difference between the cool heat source and the warm heat sink increases. An efficient ground source heat pump (GSHP) may achieve a COP of around 4. Heat pumps are ideal for exploiting low-temperature environmental heat sources: the air, surface waters or the ground. They can deliver significant environmental (CO2) and cost savings.

Sign in / Sign up

Export Citation Format

Share Document