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.

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.

Optimization Zone on the Performance of a Generalized Irreversible Magnetic Stirling Cryocooler

2001 ◽  
Vol 08 (03) ◽  
pp. 291-301 ◽  
Author(s):  
Feng Wu ◽  
Lingen Chen ◽  
Chih Wu ◽  
Fangzhong Guo
Keyword(s):  
Constant Temperature ◽  
Finite Time ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Cooling Load ◽  
Optimal Operating ◽  
Thermodynamic Performance ◽  
Temperature Heat ◽  
The Relationship ◽  
Selection Of

Finite time thermodynamic performance of a generalized irreversible magnetic Stirling cryocooler coupled to constant-temperature heat reservoirs has been analyzed in this paper. The relationship between the optimal cooling load and the coefficient of performance for the magnetic Stirling cryocooler is derived. The optimization zone on the performance of the cryocooler is obtained. The results obtained here will be useful for the further understanding and the selection of the optimal operating conditions for a magnetic Stirling cooler.

Thermodynamic Performance of an Actual Thermo-Acoustic Refrigeration Micro-Cycle

2012 ◽  
Vol 614-615 ◽  
pp. 64-68
Author(s):  
Tuo Wang ◽  
Feng Wu ◽  
Jin Hua Fei ◽  
Ming Fang Liu
Keyword(s):  
Coefficient Of Performance ◽  
Pressure Amplitude ◽  
Cooling Load ◽  
Acoustic Effect ◽  
Thermodynamic Performance ◽  
Monotonically Increasing Function ◽  
Analytic Expressions ◽  
New Type ◽  
The Relationship ◽  
Increasing Function

Thermo-acoustic refrigerator is a new type of engine, which is based on the thermo-acoustic effect. A new model which expresses as an ellipse in pressure-volume diagram is established to investigate the thermodynamic performance of an actual thermo-acoustic refrigeration micro-cycle. The demarcation points of endothermic processes and exothermic processes in the actual micro-cycle are found. The analytic expressions of the dimensionless cooling load and the coefficient of performance (COP) are deduced. The relationship between the dimensionless cooling load and the COP are investigated by numerical examples. The results show that the dimensionless cooling load is a monotonically increasing function of the COP and the pressure amplitude.

scholarly journals Validation of black-box performance models for a water-to-water heat pump operating under steady state and dynamic loads

2019 ◽  
Vol 111 ◽  
pp. 01068
Author(s):  
Elena Fuentes ◽  
Jaume Salom
Keyword(s):  
Steady State ◽  
Heat Pump ◽  
Thermal Power ◽  
Energy Performance ◽  
Heat Pumps ◽  
Black Box ◽  
Coefficient Of Performance ◽  
Performance Models ◽  
Pump Performance ◽  
Transient Phases

The use of simple mathematical models for describing the behaviour of heat pumps is important for assessing the energy performance of this equipment when installed in buildings. However, because of their simplicity, commonly used simple models, may not be able to fully account for the dynamic performance of heat pumps during transient phases. In this study, different performance black box models for an on-off water-to-water heat pump are validated by comparison with laboratory experimental results at steady state and dynamic cycling conditions. The models range from the solution based on the interpolation on the heat pump performance map to the detailed dynamic solution that combines correlations for the quasi-steady state operation and activation functions to model the transient phases. The output temperatures, electrical and thermal power and coefficient of performance from simulations were compared with experimental data from a water-to-water heat pump of 40.5 kW nominal heating capacity operating under cycling conditions. After validation with experiments, annual energy performance simulations of a tertiary building provided with a heat pump were conducted. These simulations quantifying the uncertainty expected when using heat pump performance models in simulation environments for estimating their annual energy performance.

scholarly journals Influence of desorption temperature on the thermodynamic performance of adsorption heat pump

2018 ◽  
Vol 70 ◽  
pp. 01022
Author(s):  
Katarzyna Zwarycz-Makles
Keyword(s):  
Heat Pump ◽  
Heat Pumps ◽  
Adsorption Heat ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Thermodynamic Efficiency ◽  
Efficiency Coefficient ◽  
Desorption Temperature ◽  
Adsorption Heat Pump ◽  
Thermodynamic Performance

In the paper an analysis of the desorption temperature effect on the thermodynamic efficiency of the adsorption heat pumps is presented. The thermodynamic performance of heat pump is determined by Coefficient of Performance (COP) as well as exergetic efficiency coefficient (ηex) at the adsorption equilibrium conditions and compared to the performance at heat of evaporation of the working fluid conditions. Possible estimation of reduced efficiency of adsorption silica gel/water heat pump, as distinct from the equilibrium efficiency in realistic technical system is presented.

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

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.

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.

Sign in / Sign up

Export Citation Format

Share Document