System Performance Study Of Solar Intergrated Air Source Heat Pump With Positive Pressure And Current Sharing Singe Row Outdoor Heat Exchanger

The solar intergrated air source heat pump with positive pressure and current sharing singe row outdoor heat exchanger is a small heating and cooling device which is suitable for residential and office buildings.It can not only make full use of solar energy and air energy for heating in winter,but also overcome the main drawback of other solar assisted heat pumps in cooling condition and keep high operation performance in summer.Based on the optimization of each component,the heat exchange efficiency of the equipment can be improved while making full use of renewable energy and reducing the operation energy consumption.The equipment itself is close to the people’s livelihood and can promote the construction of ecological civilization.The solar intergrated air source heat pump with positive pressure and current sharing singe row outdoor heat exchanger can greatly improve the utilization efficiency of solar energy in heating.The solar energy absorption rate and utilization rate of the unit were improved by applying the chromium-atom-layer solar energy selective absorption film with high solar energy absorption rate on the surface of the heat exchanger fins of the outdoor exchanger and the toughened glass plate with high light transmittance on the outer unit shell;the positive pressure ventilation type of the outdoor unit reduced the shadow area of the fan to the solar energy,and the arrangement of the single row heat exchanger further improved the outdoor unit solar receiving area of heat exchanger.In order to reduce the influence of solar energy on cooling efficiency in summer,sunshade equipment was adapted to reduce the absorption of solar energy by the unit.In order to solve the problem of uneven air distribution of outdoor heat exchanger caused by positive pressure ventilation of single fan,Fluent simulation and experimental research were carried out.The discretization model of the device was established and the parameters of boundary conditions were set.In order to reduce the number of grids and improve the speed of numerical simulation,the concept of equivalent porosity was proposed.The outdoor heat exchanger was equivalent to the orifice plate,which can be defined as porous jump model.Using Fluent to simulate a variety of air distribution and comparing different forms,a optimized form is proposed.The air distribution form with only setting the external uneven orifice plate can achieve more uniform air distribution and less energy consumption.The COP and EER of this form were 2.65 and 2.57 respectively without sunshade device,which were higher than those of the control group.It was verified that the uniform air distribution could make the system more efficient.COP,EER and solar energy utilization coefficient(SUC)are used to evaluate the performance of the system in heating,cooling and solar energy utilization.The system performance experiment was carried out by the method of enthalpy temperature difference.The experimental results show that the single row heat exchanger has a 3.4%-4.9% higher heat transfer efficiency than the double row heat exchanger when there is no solar radiation in both cooling and heating conditions;when there is solar radiation,the solar energy effectively improves the system COP in winter,which is up to 11.9%.However,solar radiation has an adverse effect on the summer EER of the system,hence sunshade device is taken to improve the cooling performance of the system.The utilization of solar energy by SUC evaluation system was put forward,and the comparison between different systems was carried out at the same time.The analysis of the experimental data shows that the SUC of the solar intergrated air source heat pump with positive pressure and current sharing singe row outdoor heat exchanger system is much higher than that of the fin-tube unit(39%),139.2% and 24.5% higher than those of the first generation and wide surface units respectively.The energy-saving and environmental benefits of this device mainly come from the utilization of solar energy in winter.The mathematical model of heat exchanger was established and TRNSYS was used to simulate the heating energy consumption of the device in winter.In the mathematical model,the air energy and solar energy were separated,which improved the speed and accuracy of the simulation.The simulation results show that the device can save 41.2k W · h electric energy,10.2% energy saving compared with conventional air source heat pump,and 13.18 kg of standard coal,32.55 kg of carbon dioxide,0.26 kg of sulfur dioxide and 0.13 kg of dust in the whole heating season.Adjusting the equipment control strategy and changing the compressor operation frequency according to the load can further improve the energy saving effect.Compared with on-off control strategy,the energy-saving effect of frequency conversion control strategy is increased by 26.9%.