Research On The Performance Of A Novel Fresh Air Handling Unit With Air-source Heat Pump In Severe Cold Regions

With the development of society and the improvement of people’s living standard,the problem of indoor air quality has been being paid more and more attention.However,the air conditioning system stops operating in severe cold regions in winter,when users are more inclined to evaluate the indoor environment by the room temperature as the standard,and indoor air quality is rarely paid attention to.It is urgent to set up outdoor fresh air system in severe cold areas so that fresh air that meets quality requirements can be introduced into indoor environment.There are some problems and difficulties in the application and operation of the outdoor fresh air system in severe cold regions due to the low outdoor temperature and the heavy fresh air load in winter.In order to solve the heating problem of fresh air system in cold region,a novel fresh air handling unit with air-source heat pump was proposed in this work,which mixed return air and outdoor fresh air to improve condensation pressure.According to the previous research results of outdoor fresh air system and air-source heat pump,the system form of fresh air unit was designed in this paper.At the same time,the composition of outdoor fresh air system,the operating principle,the heating cycle process,liquid extraction mode of economic apparatus,air treatment process in winter and summer working conditions and the operation mode of the unit in the whole year were discussed in detail theoretically.Due to the design requirements of the fresh air handling unit,the prototype was made.In the meantime,the experimental scheme was designed,and the parameters needed to be tested and recorded were determined and the corresponding experimental instruments were selected.Later,the processing methods of the experimental data such as compression ratio,system heat production and energy efficiency ratio are given.After the installation of the unit and the arrangement of experimental measuring points,29 groups of experiments were carried out in Harbin heating season.The functional parameters,operational parameters and heat and energy efficiency ratio of the outdoor fresh air handling unit under each test condition were compared,analyzed and evaluated.According to the experimental results,we had the first understanding of the operation effect of the fresh air unit in severe cold area.When the outdoor fresh air handling unit ran in the heating mode in Harbin heating season,the air supply temperature basically met the set requirements,and the air supply volume was relatively stable.The compression ratio of the compressor was always maintained below 10,and the exhaust temperature was lower than 95 degree.Under low temperature conditions,the outdoor fresh air handling units still had high performance coefficient,the COP of air-source heat pump was more than2.0,and COP_sys of the fresh air system was always higher than 1.6.According to the whole test results,the power consumption and heat production of the outdoor fresh air handling unit under the conditions of outdoor meteorological parameters in typical meteorological years were fitted to calculate,and the heating seasonal performance factor（HSPF）and the primary energy ratio（E）were obtained.Select the other two common outdoor fresh air systems,and the economic analysis and sensitivity analysis of the three systems were carried out.The novel outdoor fresh air handling unit had good environmental protection.Based on the measured data,the heat generation and power consumption of the whole heating season in the typical meteorological year were fitted.And the heating seasonal performance factor of the fresh air unit in the typical meteorological year was 2.15,and the primary energy ratio was 1.02.The change of operating cost had the greatest influence on the annual cost of the outdoor fresh air unit.The work in this paper had important reference significance for the promotion,application and improvement of fresh air handling unit with air-source heat pump in severe cold regions.