Heat Pump Coefficient Of Performance Research Articles

Experimental and theoretical investigation of combined solar heat pump system for residential heating

In order to investigate the performance of the combined solar-heat pump system with energy storage in encapsulated phase change material (PCM) packings for residential heating in Trabzon, Turkey, an experimental set-up was constructed. Also, a comparative study of the performance of this system has been undertaken theoretically. Simulations have been made with basic computer program of three basic combined configurations, as well as conventional solar and conventional heat pump systems in Trabzon by using meteorological data. The experimental results were obtained from December to May during the heating season for four heating systems. These systems are a conventional solar system, a series heat pump system, a parallel heat pump system and a dual source heat pump system. The experimentally obtained results are used to calculate the collector efficiency, heat pump coefficient of performance (COP), seasonal heating performance, the fraction of annual load met by free energy, storage and collector efficiencies and total energy consumption of the systems during the heating season.

Proposal of a chemical heat pump with paraldehyde depolymerization for cooling system

A chemical heat pump system with paraldehyde/acetaldehyde (Pa/A) is proposed for a cooling system. This chemical heat pump is similar to the vapor-compression heat pump. The coefficient of performance (COP) was estimated from equilibrium data. The coefficient of performance (COP) was estimated from equilibrium data. The pressure and the concentration at the reaction equilibrium state were measured for estimation of the performance of the CHP. The COP of the Pa/A system is same as the COP of a vapor-compression heat pump with CFCs.

Modeling of the Radio Frequency Electric Field Strength Developed During the Rf Assisted Heat Pump Drying of Particulates

A new “boundary value” approach to model the radio frequency (rf) electric field strength during the tf assisted drying of particulate materials has been developed and validated with experimental data. Material dielectric data at varying moisture contents and elevated temperatures were measured in a novel co-axial test cell and used in the analysis. Experimental drying results are presented showing how the simultaneous application of if heating complements heat pump drying, not only increasing drying rate, but also increasing the heat pump coefficient of performance.

Experience With a Solar Heating ATES System for a University Building

At Stuttgart University, a solar heating system for an office building with laboratories and lecture rooms was installed in 1985. It consists of 211 m2 of unglazed solar collectors, a 1050 m3 water-flooded pebble bed heat store, and a heat pump. Heat can be supplied to the store from the solar collectors or from a power station (as waste heat). The whole system has worked successfully for five years under varied strategies. In the first two heating periods, the heating strategy was aimed to collect as much solar energy as possible. Thus, about 60 percent of the heat demand could be covered by solar energy; but the yearly heat pump coefficient of performance (COP) was only around 2.76. With an improved heat pump, a monthly COP of 3.6 was obtained. Heat losses from the storage amounted to about 20 percent.

Solar-assisted heat pump and energy storage for domestic heating in Turkey

In order to improve the performance of the solar-assisted heat pump system with energy storage for domestic heating in the Black Sea region of Turkey, an experimental set-up was constructed. In this study, the solar-assisted series heat pump system with storage and parallel heat pump system with storage are experimentally investigated and compared. This experimental apparatus consists of 30 m 2 of flat-plate solar collectors, a laboratory with 75 m 2 floor area for heating purposes, a latent heat thermal energy storage tank that is filled by 1500 kg of encapsulated phase-change material (PCM), a heat pump with double evaporators (air- and water-sourced) and one condenser, a water circulating pump and other measuring equipment. The experimental results are obtained in December, January, February, March, April and May in the heating season of 1991 for the two heat pump systems used. The experimentally obtained results are used to calculate the collector efficiency, heat pump coefficient of performance (COP), system COP, storage efficiency and total energy consumption of the system during the heating season. The mean values of the collector efficiency, heat pump COP, system COP and storage efficiency were around to be 70, 4.2, 4.0, and 60%, respectively.

Energy and economic comparisons of air-to-air heat pumps and conventional heating systems for the Turkish climate

In order to investigate the energy performance of air-to-air heat pumps for residential heating in the Black Sea region of Turkey, an experimental set-up was constructed. An electrically driven air-to-air heat pump was used for heating a laboratory building with a floor of 75 m 2. The experimental results were obtained for December, January, February, March, April and May of the 1991–1992 heating season. The experimentally obtained results are used to calculate the heat pump's coefficient of performance (COP). Actual experimental performance data were used to generate third-order polynomials relating the heat pump's COP to the outdoor air temperature. Also, economic comparisons were made of the heat pump's performance with electrical resistance, oil, gas and coal-fired heating systems, using an annualised life-cycle costing method. This showed that the heat pump offers economic advantages over the oil and coal-fired boiler systems, but is not an economic alternative to the gas-fired heating system. Because the unit price of the gas is 3·84 times less than that for electricity, to become competitive with a gas-fired boiler, either the capital cost of the heat pump must be substantially reduced or its seasonal COP increased by about 60%: it should also be driven by a gas engine rather than an electric engine.

The Influence of Height Above Sea Level on the COP of Air-Source Heat Pumps Used for Water Heating

Abstract In some countries (e.g., South Africa), important market areas for air-source heat pumps are situated high above sea level, and it is therefore necessary to know what the influence of height is on the performance of heat pumps for water healing. Therefore, a study was conducted that predicts the influence of height on the coefficient of performance (COP) of air-source heat pumps. An expression was derived that gives the heat transfer to the evaporator of a heat pump as a junction of air density and enthalpy as well as the outside heat transfer coefficient. This expression was used to predict the influence of height above sea level on COP. The results were verified by means of a simulation study. It was concluded that height has little influence on COP if the evaporator of the heat pump is wet on the air side. A more significant weakening in the performance occurs, however, when the air side of the evaporator is dry.

Wind Evaporator Heat Pumps—Part II: Thermal Performance Results

Wind evaporators are alternative evaporators for air source heat pumps which rely on wind-driven or natural convection to move air across the heat transfer surfaces. A fully automatic, computer-controlled test facility which allows side-by-side testing of wind evaporator and conventional heat pumps and monitoring of weather conditions has been designed and built at University College Galway. The aim of this paper is to quantify the advantages of wind evaporators by comparing the performance of a wind evaporator heat pump with that of a conventional heat pump over an extended testing period and by examining the relationship between weather conditions and heat pump performance. In this paper, results are presented in the form of plots of coefficient of performance (COP), compressor power, evaporator and condenser heat transfers and climatic variables against time. In addition, a testing period coefficient of performance has been calculated for each heat pump. The results show that wind speed is the dominant climatic variable affecting wind evaporator heat pump performance, and that frost growth does not significantly reduce this performance. Even at extremely low wind speeds, the COP of the wind evaporator heat pump is not significantly affected. After over 460 hr of testing, the testing period COP of the wind evaporator heat pump shows a 16 percent increase over that of the conventional heat pump. (Refer to Nomenclature in Part I of this paper.)

Heat pump systems for enhancement of heat rejection from spacecraft

Temperature boosting of waste heat from spacecraft by means of heat pumps makes it possible, under some conditions, to achieve considerable savings in radiator area and mass. This study considers several possibilities for employing work-actuated and heat-actuated heat pumps (WAHP and HAHP, respectively) for this purpose. In the former case, the spacecraft power source is required to generate extra power to operate the heat pump; in the latter, use is made of the heat rejected from the power source to energize the heat pump. The mass and area savings are calculated for a range of operating parameters including the temperatures of the waste heat from the power source and payload and that of the effective heat sink. The dimensionless parameters governing the behavior are determined. It is shown that for given operating conditions, a proper choice of the temperature boost and the associated heat pump coefficient of performance leads to an optimum in radiator area and system mass savings. A detailed cycle calculation is presented for an absorption heat pump—a particularly promising HAHP with few moving parts. Design considerations are given for space-based WAHP and HAHP systems. Nomenclature A - radiator area, m2 e = power source efficiency m = system mass, kg mp = specific mass of power source, kg/kW mr = specific mass of radiator, kg/m2 Q = heat rate, kW s = solar power supplied by solar collectors per unit area, kW/m2 T = temperature, K W - electric power, kW ]8 = heat pump coefficient of performance e = emissivity of radiator surface r? = radiator fin efficiency fi = power mass penalty parameter, Eq. (14) a = Stefan-Boltzman coefficient, W/m2K4 0 = portion of Carnot efficiency

Performance of combined solar-heat pump systems

A comparative study of the performance of combined solar heat pump systems for residential space and domestic hot water heating has been undertaken. Simulations have been made with TRNSYS[1] of three basic combined configurations, as well as conventional solar and conventional heat pump systems, in two different climates, Madison, Wisconsin, and Albuquerque, New Mexico. The three combined systems are the series system in which the solar storage is used as the source for the heat pump, the parallel system in which ambient air is used as the source for the heat pump, and the dual source system in which the storage or ambient is used as the source depending on which source yields the lowest work input. The influence of collector area, number of glazings, main storage volume to collector area ratio, and heat pump coefficient of performance were determined. The results indicate that the parallel combined system is probably the most practical solar-heat pump configuration. The thermal performance at a given collector area is consistently superior to both the series or the dual source systems over the heating season. Costs and the extent to which summer cooling is a requirement determine the relative merit of the conventional heat pump, conventional heat pump, conventional solar, and parallel systems.

Significance of heat pump coefficient of performance

This paper deals with the load aspects and economic aspects of three types of residential heat pump systems which employ supplementary heat sources. It contains illustrations of their load characteristics over a wide range of annual COP (coefficient of performance), depicts relationships of the relative costs to serve these loads from long-range and short-range considerations, and provides, as a reference, load characteristics and economic data for three comparable types of resistance heating systems with their complementary electrical cooling loads, and a band of competitive operating costs to customers using gas for heating and cooling.