| With the development of economy and society and the improvement of people's living standard,the demands and consumption for traditional energy are daily on the increase.In the mean time,the p r o bl e ms of natural resources' shortages and e n v i r o n me nt a l p o l l u t i o n become more and more serious.Therefore,it is necessary to develop and utilize new types of renewable en e r g y,for example,the development and utilization of solar,air and wind energy,etc.appear a good momentum of growth.In winter,the solar water heating systems have been applied in the regions that require heating to some degree.However,because of the influence of the weather condition such as cloudy or rainy days,a single solar water heating system may lead to the phenomenon of not providing the heat continuously,even interruption.Similarly,a water heating system powered by a single air source heat pump may lead to some states of heating efficiency falling and frosting due to too low outdoor temperature.In order to make full use of the abundant solar energy resources in Lanzhou area,reduce the dependence upon traditional energy and overcome the above problems caused by a heating system powered by a single heat source,on the basis of the theories of solar and heat pump and the heating technical requirements,a design idea,technological process and operating modes for a heating system combining solar energy with a air source heat pump unit(ASHPU)are proposed in this paper.By TRNSYS software,the numerical simulation and the corresponding performance analysis for this hybrid heating system are executed,which verify the feasibility and application potential of this hybrid heating system.The main research results in this paper are as follows.1.By synthesizing the technologies of solar energy and air source heat pump and the heating technological requirements,the corresponding design idea and technological process for this hybrid heating system are proposed.Moreover,its operating modes including heating method A,heating method B and defrosting method C to obtain sanitary and hot water are analyzed in the related mechanisms.2.The working mechanism for every main component in this hybrid heating system powered by solar energy and a ASHPU is mathematically described and the type selection for main equipments in terms of the relevant calculation are carried out.3.Considering a comprehensive office building in Lanzhou area as the applied objective of this hybrid heating system,this hybrid heating system for this office building is configured and simulated by TRNSYS software.The change regularities of main running parameters that can characterize the performance of this hybrid heating system under method A,method B and method C during heating period are obtained,respectively.The results indicate that the proposed hybrid heating system can meet the requirements of heating load for this office building and indoor temperature.In addition,another numerical simulation of the method D is also carried out during the non-heating period.The results show that the method D can offer a quantity of sanitary and hot water to meet the requirements for office workers and residents and reduce the energy consumption.4.On the basis of indexes of technology,economy,energy saving,and environmental protection,etc,a comparison of the proposed hybrid heating system with other traditional heating systems is carried out.The proposed hybrid heating system has some advantages such as low operation cost,advanced technology,the effect of energy conservation and reduction of pollutant emissions from the calculating data.The research and the related numerical simulations in this paper verify the feasibility of a water heating system combing solar energy with air source heat pump and its operating modes,which exploits a new path to solve the heating problem in the cold north areas in winter and gives a certain reference role for the comprehensive utilization of the solar energy and air energy. |
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