| At present,the energy consumption of buildings in rural areas of northern China is relatively high,and heating can cause serious resource waste.The country has implemented clean energy heating renovation for heating in northern regions,with "coal to electricity" and "coal to gas" becoming the two leading directions to solve rural heating in northern China.However,due to a series of problems such as natural gas shortage in winter heating,many heating renovation projects tend to choose the "coal to electricity" plan.The air source heat pump is not only environmentally friendly and efficient,but also has the functions of heating in winter and cooling in summer.It can meet the needs of families in both winter and summer.It is fully suitable for the "coal to electricity" scheme,especially for northern rural areas without central heating.This article takes a two-story rural civil building in Luonan County,Shangluo City,Shaanxi Province as the research object.The walls of the building are constructed with EPS modules,and the external windows are composed of double-layer hollow glass and bridge cut aluminum alloy window frames.The ground and roof have insulation measures.The building uses an air source heat pump as the cold and heat source,and the end equipment for heating in winter is a floor heating radiation coil,while the end equipment for cooling in summer is a fan coil.This article conducts relevant experimental studies on the operation of air source heat pumps in the building during winter and summer seasons.During the winter experiment,based on the heating time and outdoor temperature changes,the heating period is divided into heating stage I(with a daily average temperature greater than 0 ℃),heating stage II(with a daily average temperature less than 0 ℃),and heating stage III(with a daily average temperature greater than 0 ℃).The operation plan is: the water supply temperature is set at 40 ℃,the operation time is set from 23:00 to 8:00,the power consumption during the heating period is 8426.1k Wh,and the operating cost is 2677.8 yuan.According to the study of indoor temperature,it can be concluded that the indoor temperature in heating stage I and heating stage III basically meets the design requirements of 18-24 ℃.However,when the outdoor temperature in heating stage II is relatively low,the indoor temperature cannot meet the design requirements of 18-24 ℃.In addition,the indoor temperature in rooms facing north is relatively low.During the summer experiment,the indoor temperature was set to 24 ℃ and 26 ℃,respectively.When the temperature was set to24 ℃,the indoor temperature was lower and did not meet the thermal comfort requirements for summer cooling.When the temperature was set to 26 ℃,the indoor temperature and humidity met the thermal comfort requirements for summer cooling.In addition,the daily operating power consumption was 50.6 k Wh and 36.4 k Wh,respectively.Intermittent operation experiments were conducted when the indoor temperature was 26 ℃.When the unit was running from 8:00 to 20:00,the indoor temperature and humidity met the thermal comfort requirements for 24 hours from8:00 on the same day to 8:00 on the next day.The operating power consumption was21.7 k Wh,which reduced the daily operating power consumption by 40% compared to full day operation.On the basis of the experiment,this article used TRNSYS to simulate the load of experimental buildings and traditional rural buildings in the north.The winter heat load of traditional rural buildings is 2.6 times that of the simulated heat load of the buildings studied in the paper,and the summer cooling load is 1.7 times that of the buildings studied in the paper.When heating or cooling traditional rural buildings,it will inevitably cause more energy consumption and operating costs.Due to the fact that the heating load of the building studied in the paper is much greater than the cooling load,a model of the heating system was established,and the indoor temperature and power consumption of different heating stages were verified.Relevant modifications were made to the flow distribution problem according to the design load.It was found that during the experiment,the set operating mode for heating stages I and III would result in the unit heating capacity exceeding the heating load,In the second stage of heating,the heating capacity of the unit is less than the heat load.Four operation schemes are proposed in the heating stage I and four operation schemes in the heating stage II,aiming at different intermittent operation modes of the unit that meet the indoor temperature requirements of 18-24 ℃,daytime and nighttime operation,as well as different outlet temperatures.The heating stage I and III adopt the operation plan II with a 40 ℃ outlet temperature(8:00-17:00),while the heating stage II adopts the operation plan II with a 45 ℃ outlet temperature(8:00-16:00),which saves the most electricity and reduces the power consumption by 13.7% compared to the experimental operation.Among them,the heating stage I and III adopt the operation plan one with a 40 ℃ outlet temperature(23:00-7:00),and the heating stage II adopts the operation plan one with a 45 ℃ outlet temperature(23:00-6:00)as the optimal plan.This operation plan has the best economy and indoor thermal comfort,and compared to the experimental operation,the power consumption is reduced by11%,and the operation electricity cost is reduced by 16.4%. |
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