Abstract
Three connection methods for the combined heating systems of a closed-type heat-source tower heat pump (CHTHP) and solar collector (SC) were proposed in this paper: the heat-source tower (HST) and solar collector were connected in series (HST+SC), and the solar collector and heat pump (HP) condenser were connected in series (SC+HP) and in parallel (SC//HP). The calculation module of the closed heat-source tower was built using programming software based on C++ language, and three corresponding calculation models of the combined heating systems were established in the TRNSYS. Under the climatic conditions of the cold season in Changsha, the combined heating performance of the three systems was simulated and analyzed. The results indicate that the simulation results of the established models are in good agreement with the test results, and the simulation results can be used for the research of the system’s combined heating performance. When the outdoor air temperature and solar radiation intensity are low, the HST+SC system has the best heating performance; however, when the solar radiation intensity and ambient temperature are high, the heating performance of the SC//HP system is the best. When the solar radiation intensity and outdoor air temperature are between the previous two working conditions, the SC+HP system is the best performer for heating among the three systems. On the basis of the collector area and heat pump power designed in this study, the best operating condition interval diagrams of the three combined heating systems are established.
Highlights
As residents’ living standards are continuously improved, the demand for building heating energy consumption will gradually increase, making full use of renewable energy becomes a momentous method to meet the increasing demand of building heating energy consumption [1,2,3]
There are still some shortcomings limiting the further development of solar thermal utilization technology and air source heat pump (ASHP) technology, such as the intermittence and low energy density of solar energy [7] and the phenomenon that the evaporator of the ASHP may be frosted in a low temperature environment, which leads to a decrease in heating capacity and Coefficient of Performance (COP) [8]
The system heat capacity, system input power and system COP changes are shown in Figure 7. was connected in parallel with the heat pump and worked independently, and solar radiation had no effect on the circulating fluid circulation between the heat-source tower and the heat pump system
Summary
As residents’ living standards are continuously improved, the demand for building heating energy consumption will gradually increase, making full use of renewable energy becomes a momentous method to meet the increasing demand of building heating energy consumption [1,2,3]. Solar water heating systems and air source heat pump (ASHP) systems are widely used in people’s lives because of their energy-saving properties and low cost of use [4,5]. They provide ecological solutions for heat generation, and increase energy independence [6]. Huang et al [15,16] studied and built the correlation between the heat and mass transfer coefficient and spray density and air flow density, and established the physical model of heat-source tower heat pump (HTHP) system optimization. Wen et al [17,18] analyzed and optimized the heat and mass transfer characteristics, solution regeneration and liquid-gas ratio of the OHTHP
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