The Simulation Study On Small Capacity Direct Expansion Solar-assisted Heat Pump

In recent years, with the increasing deterioration of the environmental problems in ourcountry, especially the sustained fog haze weather appears in most parts of the countryrecently, people pay more attention to environmental problems.The use of energy in China isstill in a stage of low efficiency and high energy consumption; it is mostly obvious in buildingenergy consumption.The building energy consumption accounts for most of the proportion ofthe total energy in China and hot water is the integral part of it.In the nowadays, more and more solar hot water devices are adopted in the buildings.Because of the influences of season, weather or geographical differences, the solar energyapplication efficiency is not very high. The device still needs electricity supplementary tooffer heating, which consumes larger electricity relatively.In this case, many scholars putforward to introducing the heat pump technology into the solar energy area So that Solarenergy heat pump system will overcome the shortcomings of the two and will take advantageof the two. Smaller-capacity direct expansion solar energy heat pump has the advantage ofsmall volume and big power, which help it more easily to integrate with the building and itwill certainly promote the development of solar energy heat pump.In this paper, on the basis of the thermodynamics first law and second law, we establishdirect expansion solar heat pump hot water system’(DX-SAHP) mathematical model andcarry on simulation analysis on it. Through the simulation analysis, we establish theadvantages of smaller-capacity direct expansion solar energy heat pump.In order to adapt tothe unstable intensity of solar radiation, smaller-capacity direct expansion solar energy heatpump need to adjust conversion compressor running frequency f and combine to theelectronic expansion valve synergy, by doing that,it will help compensate for the solarenergy’s shortcomings of discontinuity, low density and instability.Through establishing mathematical model of solar collector frequency conversioncompressor, evaporator, condenser, and the electronic expansion valve, we bring MATLABsoftware into the iterative calculation and build the structure parameters, operation parametersand environmental parameters.we plot the influence curve of the performance coefficient of the COP, set parameters coll, hot water heating powerQc ond, compressor power consumptionpowerWc ompand hot water. Through the study on the whole system simulation, we candraw the following conclusion: the change of the frequency conversion compressor frequencyand combination of electronic expansion valve can improve the system performance of thesolar energy heat pump effectively.