| At present,the seawater source heat pump system is mainly divided into open-type heat pump system and closed-type heat pump system,and because of the open-type heat pump system pipeline corrosion and serious biological attachment problems,resulting in short service life of seawater source heat pump,high maintenance costs.The closed seawater source heat pump system can solve the corrosion problem perfectly,and has been developed rapidly.The common front heat exchangers are spiral coil and cast-off tube.The research on capillary heat exchanger is mostly used in terminal equipment.Although heat exchangers such as spiral coils have solved the corrosion problem of seawater to pipelines,there are still some problems such as short-circuit of heat flow and difficulty in raising heat transfer capacity.Seawater source heat pump is one of the important ways to utilize renewable energy(ocean energy)in the field of HVAC.As an ideal cold and heat source,seawater can create a comfortable buildings indoors environment through the promotion of heat pump.At the same time,because of its energy-saving and environmental protection,the heat pump system also meets the policy requirements of green low-carbon development in today's society.The design of the front heat exchanger plays a decisive role in the performance of the whole seawater source heat system.Studying the forms of the front heat exchanger and giving full play to the heat transfer performance of the heat exchanger can improve the performance of the heat pump.In this study,the actual project of seawater source heat pump system based on capillary front heat exchanger was carried out,and the performance of the system and the heat transfer and resistance characteristics of capillary heat exchanger were measured and analyzed,which can provide a reference for engineering practice.Firstly,a seawater source heat pump system test bench with capillary front heat exchanger is built,and the testing instruments and equipment are installed to meet the accuracy requirements.Secondly,the operating characteristics of seawater source heat pump under different operating conditions are analyzed.Finally,the heat transfer characteristics of capillary heat exchanger under different operating conditions are analyzed,and under winter conditions.The extreme conditions of the capillary heat exchanger are analyzed,and the resistance characteristics of the capillary under different working conditions and different connection modes are analyzed,and the calculation formulas in different forms are summarized to provide the basis for the selection of the capillary heat exchanger.Based on the above research,the main conclusions are as follows:(1)According to the analysis of test data,the indoor design temperature of the seawater source heat pump system is 18?,while the average indoor temperature is 22.4?,which is much higher than the design temperature;the indoor design temperature is 25?,and the measured average indoor temperature is 22.49?,which is less than the design temperature.Therefore,when using seawater source heat pump,whether in heating or cooling,the actual indoor effect can meet the design requirements.(2)Analyzing the test data,the average COP of the heat pump unit is 3.7,the average COPs of the whole seawater source heat pump system is 2.99,the average EER of the heat pump unit is 3.96 and the average EERs of the whole seawater source heat pump system is3.15.(3)The capillary heat transfer was analyzed in winter and summer through the test of heating and cooling conditions of heat pump system.The average heat transfer per unit area was 31.5 W/m~2 under heating conditions and 56.69 W/m~2 under refrigeration conditions.It is found that the heat transfer per unit area in summer is higher than that in winter.(4)The energy efficiency analysis of the capillary front heat exchanger shows that the energy efficiency of the capillary heat exchanger is above 71.42%,and the heat transfer efficiency is higher,and the energy efficiency has no direct relationship with the flow rate.(6)The capillary impedance is studied,and the resistance of two capillaries in series and in parallel under different flow rates is analyzed.At the same time,different forms of capillary parallel connection are analyzed,and the impedance calculation formula is given:S_n=(1.055E+06)/n~2.This research is based on the practical application of the capillary front-end heat exchanger in the seawater source heat pump system.The research results can provide a reference for practical engineering design. |
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