Vapor Compression Heat Pump Research Articles

Analisis Sistem Heat Pump Kompresi Uap untuk Pengeringan Gabah

Analisis Sistem Heat Pump Kompresi Uap untuk Pengeringan Gabah

Experimental performance evaluation of heat pump by using CO2 as a refrigerant

In this experiment the refrigerant used is CO2 which is naturally available, eco friendly, economical, non toxic, non flammable and non corrosive. Its Ozone Depletion Potential (ODP) is zero and minimum Global Warming Potential (GWP). The performance evaluation of prototype vapor compression heat pump model was performed and evaluated the different parameters like COP (Co-efficient of performance), LMTD (Logarithmic mean temperature difference) and outlet water temperature of condenser. The experiment is carried out for two different condensers by varying mass flow rate and pressure. The water in the shell side was heated by absorbing heat from refrigerants in the tube side of condensers by counter flow heat exchanging method. The experimental result indicates fairly good COP with the use of CO2 refrigerant. These advantages of CO2 as a refrigerant favors the replacement for globally used refrigerant with CO2.

Pervaporation membrane bioreactor with permeate fractional condensation and mechanical vapor compression for energy efficient ethanol production

Improved process separation factor and heat integration are two key issues to increase the energy efficiency of ethanol production in a pervaporation membrane bioreactor (PVMBR). A PVMBR with permeate fractional condensation and mechanical vapor compression was developed for energy efficient ethanol production. A condensation model based on the mass balance and thermodynamic equilibrium in the partial vacuum condenser was developed for predicting the purification performance of the permeate vapor. Three runs of ethanol fermentation-pervaporation experiment were carried out and ethanol concentration of higher than 50wt% could be achieved in the final condensate, with the separation factor of the process for ethanol increased to 20. Ethanol production could be enhanced in the bioreactor and 17.1MJ of the energy could be produced in per liter of fermentation broth, owing to 27.0MJ/kg heating value of the recovered ethanol. Compared with the traditional pervaporation process with low temperature condensation for ethanol production, 50% of the energy would be saved in the process. The energy consumption would be further reduced, if the available energy of the permeate vapor was utilized by integrating the mechanical vapor compression heat pump.

Thermodynamic analysis of vapor compression heat pump cycle for tap water heating and development of CO2 heat pump water heater for residential use

The ideal vapor compression cycle for tap water heating and its coefficient of performance (COP) have been studied theoretically at first. The ideal cycle is defined as the cycle whose high temperature heat source varies temperature with constant specific heat and other processes are same as the reverse Carnot cycle. The COP upper limit of single stage compression heat pump cycle for tap water heating with various refrigerants such as fluorocarbons and natural refrigerants was calculated. The refrigerant which achieves the highest COP for supplying hot water is CO2. Next, the prototype of CO2 heat pump water heater for residential use has been developed. Its outline and experimental results are described. Finally its further possibility of COP improvement has been studied. The COP considered a limit from a technical point of view was estimated about 6.0 at the Japanese shoulder season (spring and autumn) test condition of heating water from 17°C to 65°C at 16°C heat source air temperature (dry bulb)/12°C (wet bulb).

Mathematical modeling and environmental analysis of heat pumps integrated in aprocess to treat spent pickling liquors

Spent pickling liquors are hazardous waste due to their high concentration of metals and presence of several acids.Different processes are developed for treatment of spent pickling liquors aiming to energy efficiency and there are few works in literature about the use of heat pumps (energy efficient and environmentally friendly process) to this purpose. In this article a new process for regeneration of spent pickling liquors producing fertilizers (FeSO4, ZnSO4, FeSO4·7H2O, ZnSO4·7H2O) and integrated with heat pumps is developed. A vapor compression heat pump with indirect expansion is used in evaporation and crystallization section. A sensitivity analysis is carried out to evaluate the effect of heat pump parameters on coefficient of performance. Through response surface a mathematical model is developed for coefficient of performance, CO2 emissions and primary energy consumption. In addition a factorial design allows to evaluate the significance of same factors on them. In this way process parameters and not heat pump parameters are used for factorial design: the integration of heat pumps is more enhanced.Results show that overall the two heat pumps, compared to an industrial boiler, allow a reduction of 38% of CO2 emissions and Total Equivalent Warming Impact, reduction of 39% and 57% on tons of equivalent petroleum and costs respectively, according to European Union climate package.Economical incentives in terms of white certificates are obtained so the process is more economically feasible. A Life Cycle Analysis is carried out to evaluate the environmental advantage of heat pumps over the industrial boilers. Results show that the environmental sustainability of all heat pump systems could improve with the greater penetration of renewables in the electricity mix.The future construction of the plant will allow to verify the obtained results in order to realize a more accurate mathematical model that optimizes all process.

HEAT PUMPS APPLICATION IN FLOW-SHEET OF HEAT GENERATION AT THERMAL POWER PLANTS

This paper deals with the possibility of installing the vapor compression heat pumps’ (heat capacity less 3 MW) in order to increase the efficiency of production of heat and electrical energy for thermal power stations. All calculations were made for thermal power plant of the branch “Nevsky” JSC “TGC-1” – “Severnaya” CHP-21. The large number of sources of waste heat, such as cooling water turbine condensers, flue gas boilers, waste heat boilers, industrial water for cooling machinery, etc., is sufficient grounds to assert term use heat pumps for recycling this waste heat. The paper proposes the use of heat pumps for heating and feeding of their own economic need station, as well as heating the raw water before the chemical water treatment shop. The basic technical and economic parameters of stations for specific modes of operation of the stations are calculated

Performance analysis of liquid flooded compression with regeneration for cold climate heat pumps

In regions with sub-freezing winter temperatures, the performance of conventional air-source vapor compression heat pumps drop drastically during extended periods of low outdoor ambient temperatures. Modifying the basic cycle configuration with liquid flooded compression and regeneration reduces the thermodynamic inefficiencies associated with the heat pump equipment and increases energy efficiency with less degradation in heating capacity especially at low ambient temperatures. Flooding non-volatile liquid along with refrigerant vapor stream into the compressor leads to a near isothermal compression process and thereby reduces desuperheating losses in the condenser. Regeneration improves the system performance by reducing throttling losses in the expansion device. The performance of a heat pump operating with flooded compression and regeneration has been analyzed for three sub-freezing outdoor ambient climatic regions: Boston, Indianapolis and Minneapolis. The results indicate that at −10 °C ambient temperature, COP (heating) of the flooded compression with regeneration cycle was approximately 13% higher than the standard vapor compression cycle. The Heating Seasonal Performance Factor (HSPF) of a flooded compression with regeneration cycle for Boston, Indianapolis and Minneapolis was approximately estimated to be 9%, 10% and 13% higher than the standard vapor compression cycle respectively.

Space Vibration Simulation Test of Vapour Compression Heat Pump

Vapour compression heat pump will have good prospects in future large-scale spacecraft thermal control technology. Its environmental reliability and safety needs to be tested on the ground before being carried with the spacecraft launch. Vibration test is used to assess the anti-vibration capability in its transport and use. It is essential to build a performance test system of vapour compression heat pump to explore its operating characteristics at a given random vibration conditions. The results shows that the vapour compression heat pump is normal operation after the vibration and the cooling performance (COP) of 3.09 is achieved. Vibration test is equipped to provide a guarantee for future success carrying. The performance of vapour compression heat pump at high and low temperature and vacuum environment will be carried out.

Utilization of the horizontal ground heat exchanger in the heating and cooling system of a residential building

AbstractThis paper presents the results of thermodynamic analyses of a system using a horizontal ground heat exchanger to cool a residential building in summer and heat it in the autumn-winter period. The main heating device is a vapour compression heat pump with the ground as the lower heat source. The aim of the analyses is to examine the impact of heat supply to the ground in the summer period, when the building is cooled, on the operation of the heating system equipped with a heat pump in the next heating season, including electricity consumption. The processes occurring in cooling and heating systems have an unsteady nature. The main results of the calculations are among others the time-dependent values of heat fluxes extracted from or transferred to the ground heat exchanger, the fluxes of heat generated by the heat pump and supplied to the heated building by an additional heat source, the parameters in characteristic points of the systems, the temperature distributions in the ground and the driving electricity consumption in the period under analysis. The paper presents results of analysis of cumulative primary energy consumption of the analyzed systems and cumulative emissions of harmful substances.

ТЕПЛОНАСОСНІ ТЕХНОЛОГІЇ ТА ЇХ ПОТЕНЦІЙНИЙ ВПЛИВ НА ПРОБЛЕМИ ЕНЕРГОЕФЕКТИВНОСТІ ТА ЗАХИСТУ НАВКОЛИШНЬОГО СЕРЕДОВИЩА В ЕНЕРГЕТИЧНОМУ СЕКТОРІ УКРАЇНИ

The increasing demand of energy sources for urban, household and industrial facilities requires strategies development for seeking new energy sources. In recent years an important problem is to have energy storage, energy production and energy consumption which fulfill the environment friendly expectations. A lot of attention is devoted to renewable energy sources. One of the most attracting among them is energy production form geothermal sources. At a few meters below the earth’s surface the underground maintains a constant temperature in an approximation through the year allowing to withdraw heat in winter for heating needs and to surrender heat during summer for air-conditioning purposes. Heat pump is a rapidly developing technology for heating and domestic hot water production. Using ground as a heat source, heat exchange is carried out with heat pumps compound to vertical ground heat exchanger tubes that allows the heating and cooling of the buildings utilizing a single unit installation. Heat pump unit provides a high degree of productivity with moderate electric power consumption. In this paper a theoretical performance study of a vapor compression heat pump system with various natural and synthetic refrigerants (HFCs) is presented. Operation mode of the heat pump unit was chosen according to European Standard EN14511-2:2007 and EN255-2. An influence of discharge temperature on system performance was evaluated at different boiling temperatures. The comparison of mass flow rate and coefficient of performance for considered refrigerants at constant cooling capacity and condensation temperature was performed.

Design and Thermodynamic Analysis of a Steam Ejector Refrigeration/Heat Pump System for Naval Surface Ship Applications

Naval surface ships should use thermally driven heating and cooling technologies to continue the Navy’s leadership role in protecting the marine environment. Steam ejector refrigeration (SER) or steam ejector heat pump (SEHP) systems are thermally driven heating and cooling technologies and seem to be a promising technology to reduce emissions for heating and cooling on board naval surface ships. In this study, design and thermodynamic analysis of a seawater cooled SER and SEHP as an HVAC system for a naval surface ship application are presented and compared with those of a current typical naval ship system case, an H2O-LiBr absorption heat pump and a vapour-compression heat pump. The off-design study estimated the coefficient of performances (COPs) were 0.29–0.11 for the cooling mode and 1.29–1.11 for the heating mode, depending on the pressure of the exhaust gas boiler at off-design conditions. In the system operating at the exhaust gas boiler pressure of 0.2 MPa, the optimum area ratio obtained was 23.30.

Experimental Evaluation of Thermal Performance of Solar Assisted Vapor Compression Heat Pump

The thermal performance of indirect expansion solar assisted heat pump, IX-SAHP, was investigated experimentally under Iraqi climate. An Indirect-Solar Assisted Heat Pump system was designed, built, instrumented and tested. Experimental tests were conducted by varying the controlling parameters to investigate their effects on the thermal performance of the IX-SAHP such as cooling water flow rate, heating water flow rate, ambient temperature and solar radiation intensity. The investigation covered values of cooling water flow rate of (2, 3, 4, 5 l/min) and heating water flow rate of (2, 3, 4, 5 l/min) under meteorological condition of Baghdad from November 2014 to January 2015.
 The results indicated that the performance of the IX-SAHP is not dependent on the heating water flow rate. On the contrary of heating water flow rate, cooling water flow rate has significant effect on the thermal performance of the system. The COP of the heat pump system is decreased with increasing cooling water flow rate. The collector heat gain increase with increasing the solar radiation and ambient temperature, this leads to increase in COP from 2.2 to 2.39 as the ambient temperature and solar radiation increase from 9.9℃ and 268 W/m2 to 14.9 ℃ and 689 W/m2 respectively.
 

The performance test of a modified miniature rotary compressor in upright and inverted modes subjected to microgravity

Vapor compression heat pump is a new concept of thermal control system and refrigerator for future space use. Compressor is a key component in the vapor compression heat pump. Development of compressor capable of operating in both microgravity (10 E-6 g) and lunar (1/6 g) environments is urgently needed for space thermal control systems based on heat pump technique. In this paper, a miniature rotary compressor by ASPEN company was modified to realize acceptable compressor lubrication and oil circulation in microgravity environments. An experimental system was built up to check the performance of the modified compressor subjected to microgravity. A performances comparison of inverted compressor with upright one was made. The influences of operating parameters such as refrigerant charge, cooling water temperature as well as compressor speed on the performances of vapor compression heat pump were investigated. The results show that the modified miniature rotary compressor in inverted mode can operate stably in a long period, which indicates that the modified compressor can be employed in microgravity environments. Compressor discharge temperature increased or decreased while COP changed more obviously with cooling water temperature and speed in microgravity. In most cases, performance of the upright compressor is superior to that of the inverted one. But when the compressor speed is from 1500 rpm to 2500 rpm or the coolant temperature is between 20 and 25 degrees, the performance of inverted compressor is better. The highest discharge temperature of the inverted compressor can be as high as 1.7 times that of the upright one. The maximum of heating COP and cooling COP of upright compressor is respectively 1.21 and 1.16 times that of inverted compressor. The study of modified miniature rotary compressor on gravity-independence provides an experimental basis and lays foundation for space applications.

Experimental Research on Water Boiling Heat Transfer on Horizontal Copper Rod Surface at Sub-Atmospheric Pressure

In recent years, water (R718) as a kind of natural refrigerant—which is environmentally-friendly, safe and cheap—has been reconsidered by scholars. The systems of using water as the refrigerant, such as water vapor compression refrigeration and heat pump systems run at sub-atmospheric pressure. So, the research on water boiling heat transfer at sub-atmospheric pressure has been an important issue. There are many research papers on the evaporation of water, but there is a lack of data on the characteristics at sub-atmospheric pressures, especially lower than 3 kPa (the saturation temperature is 24 °C). In this paper, the experimental research on water boiling heat transfer on a horizontal copper rod surface at 1.8–3.3 kPa is presented. Regression equations of the boiling heat transfer coefficient are obtained based on the experimental data, which are convenient for practical application.

Analysis of different heat pumping technologies integrating small scale solid oxide fuel cell system for more efficient building heating systems

Development of advanced heating systems, able to reduce the energy consumption of buildings is still an open issue. Different technologies, either already at commercial level or in a pre-commercial phase, are available. Among them, heat pumps and fuel cells represent good options, thanks to their high efficiency and flexibility of operation.The present paper analyses one of the possible ways to integrate a heat pump with a micro-Combined Heat and Power (CHP) based on Solid Oxide Fuel Cell (SOFC) technology, in order to increase the overall efficiency of the building heating system. Three different heat pumping technologies (namely vapour compression, absorption and adsorption) have been employed.Starting from performance data of commercial appliances (vapour compression and absorption heat pumps) and from performance experimentally measured at the CNR ITAE for appliances at prototyping level (adsorption heat pump and SOFC), a numerical model has been developed in TRNSYS. Simulations performed demonstrated that the overall yearly efficiency can be improved up to 30%, exploiting the heat released by the micro CHP to reduce the heat produced by the heat pump.

Performance modeling of air cycle heat pump water heater in cold climate

Air (reverse Brayton) cycle has promising features in cold climate heat pump applications. In this study, an air cycle heat pump water heater (ACHPWH) simulation model considering the off-design performance of components was developed and validated with experimental data from literature. With this model, the performance of ACHPWH was numerically compared with two typical vapor compression heat pump water heaters (VCHPWH) under two different heating schemes, namely instantaneous heating and recirculation heating. For instantaneous heating, the COP of ACHPWH is comparable to that of VCHPWH when supplying high temperature water or operating at low ambient temperature. A significant improvement on annual performance would be achieved as well if higher efficient compressor and expander were applied in ACHPWH system. For recirculation heating, although the COP gap got larger, ACHPWH would save plenty of heating time when operating at low ambient temperature.

Experimental Research on the Effect of 2‐Ethylhexanol on Water Boiling Heat Transfer at Subatmospheric Pressure

The addition of small amounts of surfactant to water can enhance boiling heat transfer substantially. In this experiment, 2‐ethylhexanol is used as the surfactant, and the critical micelle concentration (CMC) of the 2‐ethylhexanol aqueous solution is determined to be 1000 mg/L. The boiling heat transfer coefficients of the solutions in different concentrations on a horizontal copper rod surface at subatmospheric pressures (1.8 kPa to 3.3 kPa) are calculated according to the experiment results. The results indicate the following: when the concentration is 500 mg/L (lower than the CMC), the boiling heat transfer can be enhanced by up to 22%; when the concentration is 1000 mg/L (equal to the CMC), enhancement is up to about 60%; when the concentration is 2000 mg/L (two times the CMC), boiling heat transfer is diminished by about 60%. To a certain extent, this experiment will guide the enhancement of evaporator heat transfer in water vapor compression refrigeration and heat pump systems.

Experimental Investigation on a Linear-compressor Driven Travelling-wave Thermoacoustic Heat Pump

Abstract Heat pump system, offering economical alternatives in recovering waste heat from different sources for using in various industrial, commercial and residential applications, is considered to be a very environmentally-friendly heat and power transfer system. In this paper, to solve the problems of traditional vapour compression heat pump working in unconventional conditions, a novel TWTAHP (travelling-wave thermoacoustic heat pump) is presented to meet the requirement of working in ultra-low temperature. Base on the theoretical simulation and structure optimization, an experimental apparatus for preliminary test has been built, which is only one single independent unit from the whole loop of the TWTAHP system. The results show that the simulation and the testing results were agreeable as expected. Under the -20°C environment temperature and the 50°C heating temperature, we could obtain a maximal COP h (heating COP) of 2.1 and 260W heating capacity for one unit by consuming acoustic power less than 200W. Furthermore, a COP h above 3.0 could be achieved when the ambient temperature was raised to 0°C.

ИСПОЛЬЗОВАНИЕ ДИОКСИДА УГЛЕРОДА КАК ЭФФЕКТИВНОГО РАБОЧЕГО ТЕЛА В ХОЛОДИЛЬНЫХ МАШИНАХ: ИСТОРИЯ, НЫНЕШНЕЕ СОСТОЯНИЕ И ПЕРСПЕКТИВЫ

As the working substance vapor compression refrigeration machines (VCRM) and heat pumps (HP) can use different gases. These include not only specifically synthesized chemical compounds, but also natural refrigerants - ammonia, carbon dioxide, hydrocarbons. Described cooling cycles useful for work a carbon dioxide (R744). Discussed subcritical, transcritical, throttle, and throttle-expander cascade cycle in which carbon dioxide used as the low-temperature refrigerant circuit. Attention paid to the analysis of the merits of carbon dioxide cycle, which enabled the compressor of Vorhis. Shows a comparison the characteristics of the throttle cycles at different temperatures cooling, one- and two-stage compression. Is set out short history of creation refrigeration units and heat pumps operating on CO2, indicated their main manufacturers producing equipment, taking into account characteristics of the working substance which be used. The advantages of heating and cooling systems working on carbon dioxide, compared with systems using alternative refrigerants.

Low grade waste heat recovery using heat pumps and power cycles

Thermal energy represents a large part of the global energy usage and about 43% of this energy is used for industrial applications. Large amounts are lost via exhaust gases, liquid streams and cooling water while the share of low temperature waste heat is the largest.Heat pumps upgrading waste heat to process heat and cooling and power cycles converting waste heat to electricity can make a strong impact in the related industries. The potential of several alternative technologies, either for the upgrading of low temperature waste heat such as compression-resorption, vapor compression and trans-critical heat pumps, or for the conversion of this waste heat by using organic Rankine, Kalina and trilateral cycle engines, are investigated with regards to energetic and economic performance by making use of thermodynamic models. This study focuses on temperature levels of 45–60 °C as at this temperature range large amounts of heat are rejected to the environment but also investigates the temperature levels for which power cycles become competitive. The heat pumps deliver 2.5–11 times more energy value than the power cycles in this low temperature range at equal waste heat input. Heat engines become competitive with heat pumps at waste heat temperatures at 100 °C and above.