共查询到20条相似文献,搜索用时 15 毫秒
1.
An analytical and computational model for a solar assisted heat pump heating system with an underground seasonal cylindrical storage tank is developed. The heating system consists of flat plate solar collectors, an underground cylindrical storage tank, a heat pump and a house to be heated during winter season. Analytical solution of transient field problem outside the storage tank is obtained by the application of complex finite Fourier transform and finite integral transform techniques. Three expressions for the heat pump, space heat requirement during the winter season and available solar energy are coupled with the solution of the transient temperature field problem. The analytical solution presented can be utilized to determine the annual variation of water temperature in the cylindrical store, transient earth temperature field surrounding the store and annual periodic performance of the heating system. A computer simulation program is developed to evaluate the annual periodic water and earth temperatures and system performance parameters based on the analytical solution. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
2.
Ali Fouda Sameh A. Nada Abdullah S. Bin Mahfouz A. Al-Zahrani Hassan F. Elattar 《国际能源研究杂志》2020,44(8):6631-6650
In previous investigations, humidification-dehumidification (HDH) solar-assisted desalination systems were designed produce the daily fresh water during sun hours which lead to big sizes and unsteady systems. In the present study, integration of solar-assisted HDH desalination system with heat recovery and thermal energy storage unit is developed to enhance system productivity, reduces auxiliary power consumptions and system size and assure system continuous operation. The mathematical modelling based on energy and mass conservation equations is presented and solved using iterative techniques by C++ and engineering equation solver software. Detailed parametric study of the developed system is conducted for wide ranges of operating conditions and design parameters to study the effects of integrating the HDH system with solar collectors, heat recovery and thermal energy storage units on the system performance. The results revealed that (i) this integration improves system productivity and reduces operating cost, (ii) increasing air to water mass ratio and sea water temperature and decreasing ambient humidity decrease water productivity and gained output ratio (GOR) and increase operating cost parameter (OCP) and (iii) increasing air inlet temperature and sea water flow rates increase GOR and decrease OCP. Comparison with previous systems showed that the proposed system reduces the electric heating power of the system at solar noon by 37% at MR = 0.5 and gives daily fresh water productivity (123.7 kg/h) two times more than previous systems with comparable OCP (0.099 $/kg). 相似文献
3.
An experimental solar assisted heat pump space heating system with a daily energy storage tank is designed and constructed, and its thermal performance is investigated. The heating system basically consists of flat plate solar collectors, a heat pump, a cylindrical storage tank, measuring units, and a heating room located in Gaziantep, Turkey (37.1°N). All measurements are automatically collected as a function of time by means of a measurement chain feeding to a data logger in combination with a PC. Hourly and daily variations of solar radiation, collector performance, coefficient of performance of the heat pump (COPHP), and that of the overall system (COPS) are calculated to evaluate the system performance. The effects of climatic conditions and certain operating parameters on the system performance parameters are investigated. COPHP is about 2.5 for a lower storage temperature at the end of a cloudy day and it is about 3.5 for a higher storage temperature at the end of a sunny day, and it fluctuates between these values in other times. Also, COPS turns out to be about 15–20% lower than COPHP. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
4.
5.
For grain in-store drying, a solar assisted drying process has been developed, which consists of a set including a solar-assisted heat pump, a ventilation system, a grain stirrer, etc. In this way, low power consumption, short cycle time and water content uniformity can be achieved in comparison with the conventional method. A solar-assisted heat pump drying system has been designed and manufactured for a practical granary, and the energy consumption performance of the unit is analyzed. The analysis result shows that the solar fraction of the unit is higher than 20%, the coefficient of performance about system (COPS) is 5.19, and the specific moisture extraction rate (SMER) can reach 3.05 kg/kWh. 相似文献
6.
针对由天气变化导致太阳能利用不稳定和寒冷地区热泵性能低的问题,文章介绍了一种基于相变储能的太阳能空气源热泵系统,该系统能够根据气象情况灵活切换4种供暖模式,大大减少了系统耗电量。文章通过独特设计的储能冷凝器,不仅可以调节太阳能空气源热泵系统能量分配,改善太阳能空气源热泵系统制热量和建筑热负荷之间不平衡的供需关系、提高太阳能利用率,还可以提高空气源热泵低温性能,快速恢复供暖,从而实现提高太阳能空气源热泵系统整体性能的目的。文章以石家庄农村某户为研究对象进行研究,研究结果表明,太阳能空气源热泵系统供暖效果较好,太阳能空气源热泵系统COP最大值为5.19,节能环保效益十分明显。 相似文献
7.
8.
Long-term performance of solar-assisted heat pump water heater 总被引:1,自引:0,他引:1
A long-term reliability test of an integral-type solar-assisted heat pump water heater (ISAHP) was carried out. The prototype has been running continuously for more than 13,000 h with total running time >20,000 h during the past 5 yr. The measured energy consumption is 0.019 kWh/l of hot water at 57 oC that is much less than the backup electric energy consumption of the conventional solar water heater. 相似文献
9.
10.
在自行搭建的双蓄能实验平台上进行了制冷兼蓄热实验研究,对比了制冷兼蓄热模式和一般制冷模式,探讨了不同冷冻水流量和不同风机盘管风量对机组性能的影响.实验结果表明:蓄热对机组制冷端的影响很小,但是由于回收了大量的冷凝热,使得机组的综合能效比得到大幅提高,因此蓄热对空调节能具有较大作用.此外,在制冷兼蓄热模式下,冷冻水流量或风机盘管风量越大,机组的综合能效比越大,当风量为1033 m3/h,冷冻水流量为972 L/h时,机组综合能效比高达7.06. 相似文献
11.
化学热泵是高效,环保的新型能源技术,在余热回收,储热,可再生能源等领域具有广泛的应用前景.本文综述了化学热泵系统的一般理论和在储热技术中的应用,介绍了化学热泵系统技术在反应与工质对选择,传热强化以及工业研究与应用等方面的发展. 相似文献
12.
13.
《Applied Thermal Engineering》2014,62(2):823-829
The world is facing a challenge to reduce energy use to meet the environmental goals set for the future. One factor that has a great impact on the energy performance of buildings is the ventilation losses. To handle these losses, heat recovery systems with rotating heat exchanger are often implemented. These systems have been shown to recover about 60–70% of the energy in the exhaust air on an annual basis.After a heat recovery system is installed it is hard to improve the efficiency of the installed recovery system with an acceptable economic payback period. In the present paper one way to improve the energy performance of a building with this type of heat recovery system by the use of a heat pump is investigated by simulations in TrnSys.The heat pump system is arranged so that the evaporator is connected to a heat exchanger mounted in the exhaust airstream after the energy wheel, and the condenser of the heat pump is mounted so that the temperature of return water from the heating coil is increased.The simulations show that there is a possibility to increase the heat recovery rate of the air handling unit in a significant way by retrofitting a heat pump to the system. 相似文献
14.
Currently, hybrid renewable energy systems with thermal energy storage have various advantages and are widely used. This paper investigated the performance of a solar-assisted air source heat pump system with energy storage (SASHPS-ES) in Beijing, China, and proposed an optimal operation mode based on economic evaluation. The results indicate that with the optimal heat storage ratio of 50%, the rated capacity of the air source heat pump (ASHP) of the SASHPS-ES system can be reduced by 16.7%, decreasing its annual total cost by 26.5% under a peak-valley electricity price policy. The price of 620¥/m2 is critical for the solar collectors. The economics of SASHPS-ES is better than that of an air source heat pump system with energy storage (ASHPS-ES) when the price of the selected solar collector units is less than this critical price (without subsidies from the government). In the current local market, the promotion of SASHPS-ES systems and other solar energy applications requires government subsidies for a period of time. The results can guide the utilization and popularity of SASHPS-ES in China. 相似文献
15.
16.
17.
Integral-type solar-assisted heat pump water heater 总被引:2,自引:0,他引:2
An integral-type solar-assisted heat pump water heater (ISAHP) is designed and tested in the present study. The storage tank and the Rankine cycle unit are integrated together to make a more compact size. A thermosyphon loop is used to transfer the heat from the condenser to the water storage tank. The highest COP obtained in the tests is 3.83. 相似文献
18.
19.
20.
介绍了一种新型笼屉式相变蓄热水箱,通过实验测试对比分析相变蓄热水箱与普通蓄热水箱对太阳能组合系统的太阳能保证率及系统能效比的影响。实验表明:同等水箱容积,使用相变蓄热水箱时太阳能集热系统的小时集热量为普通蓄热水箱的3.7倍,相变蓄热水箱有利于提高太阳能保证率及系统能效比。在太阳能辐照强度相似的情况下,相变蓄热水箱会使太阳能保证率平均提高72%,使系统能效比平均提高26%。同时相变蓄热水箱可减少夜间水箱上部的热损失,使水箱上部水温降减少50%。 相似文献