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Heat recovery ventilation (HRV) is type of energy saving ventilation. It has been widely used in animal house to alleviate contradiction between thermal comfort and ventilation in recent years. However, air heat exchanger freeze of HRV caused by severe cold weather limited HRV application in northeast China. It is necessary to find an economic way to ensure HRV being operated without freezing. Establish a more reasonable integration of heating and ventilation system in severely cold area. An experiment was conducted in rabbit house during winter in Arun Banner, northeast China. The rabbit house was heated by a coal boiler in the next room. Hot water produced by boiler was supplied to heating radiator inside the rabbit house. The boiler room was warm because of some extra heat release by boiler. To prevent freezing, the boiler room was used to preheat cold fresh air before it entered the heat exchanger. The HRV was installed on the ground of the rabbit house. It was an integration of HRV and boiler heating system. Temperature, relative humidity and concentration of noxious was measured with automatic recording sensor instrument. Data was collected to evaluate the decrease in air pollutants and air temperature of the rabbit house. Preheating effect of the boiler room and the HRV were tested when the system was in operation. The performance of the HRV and prevention of freezing in heat exchanger was evaluated in typical cold weather in northeast China. The economic benefit of the system was analyzed. The results showed that when the HRV and boiler system began to operate, concentrations of ammonia (NH3) and carbon dioxide (CO2) in rabbit house dropped by 46% and 64%, respectively. Moreover, indoor air temperature only dropped by an average of 1.8 ℃ when the outdoor air temperature varied from -15.8 ℃ to -11.8 ℃. It means that the system can significantly improve indoor air quality with barely a slight decline of indoor air temperature. Respiratory and skin disease decreased by 16% and 4%, respectively. It is great potential for better health and production of rabbits. The boiler room heated fresh air from -13.8 ℃ to -3.7 ℃, and the HRV heated fresh air from -1.0 ℃ to 5.5 ℃ on average. No frozen of the heat exchanger was observed. Heated load of the boiler room and the heat recovery load of the HRV were 12.6 kW and 5.0 kW, respectively. Sensible heat recovery efficiency of the HRV was 75.6%. Coefficient of performance of the HRV was 6.2. The system was operated efficiently. The method of freezing prevention ensure HRV in good condition among the whole cold season in northeast China. It is an economic option because the system can operated without extra energy consumption. The return of investment is 3 years in this work condition. The integration of HRV and boiler allowed HRV and boiler heating to operate with high efficiency and solve the contradiction between heating and ventilation in severely cold weather in the rabbit house. This finding can provide a sound reference for the design of animal house heating and ventilation system in severely cold climate northeast China [ABSTRACT FROM AUTHOR]

Housing environment has become a driving factor on hen health, egg quality and efficient production in intensive poultry industry. In large layer poultry housing system, an environmental index is typically used to control air conditions, including air temperature (T), relative humidity (RH) and concentration of carbon dioxide (CO2) in different season. In hot seasons, thermal environment of laying hen housing is usually assessed using the temperature humidity index (THI) via the online monitored temperature and relative humidity. However, the simple assessment cannot meet the harsh requirement of indoor air quality in a large layer house, as the stocking density increases in recent years. In this paper, a comprehensive environmental index (CEI) was proposed based on the radar map to integrate the impacts of both thermal and air quality factors, in order to systematically assess the environment comfort of the birds. A LabVIEW software system was selected to illustrate the environmental comfort using the fuzzy mathematics. Five key environmental factors, including temperature, RH, air velocity, concentration of CO2 and ammonia (NH3), were used to evaluate the environmental comfort of laying hen housing, where the their weights were normalized in a radar map. In the visualized system, early warning can be delivered when either a single factor or the CEI was over the prescribed value, and thereby a quick action can be taken to adjust the environmental conditions in the layer housing to a comfort level. A field measurement was carried out at a commercial layer breeder farm in Hebei province from January to February, and from July to August, 2019. The experimental results indicated that a good performance of the CEI can be obtained to assess the comprehensive environment in the tested house via monitoring the five environmental indexes. The specific sensors were properly settled in the henhouse. The data of environmental conditions was collected to verify, and then the maximum of five indexes were selected for later use. During the summer daytime, the CEI agreed well with the THI, indicating the positive impacts of thermal environment on the comfort of the birds, while it performed better to integrate the thermal and air quality at night time. In winter, the increase in the weight of CO2 concentration can contribute to the CEI for the comfort in layer housing system. The in situ monitoring data in the actual use demonstrated that the CEI can efficiently represent the change of comprehensive environmental comfort in the chicken house, and respond to the interaction between environmental factors in each period, especially when the air quality has an increasing influence on the comprehensive environmental comfort at night in summer and in winter. The findings can provide a promising method to systematically evaluate the housing environment via the five key factors in laying hen housing, further to improve the birds comfort via precisely controlling the air conditions in intensive poultry production. [ABSTRACT FROM AUTHOR]