The heating and cooling potential of water-air heat exchange system

• Main Authors: Shu-Wei Chang, 張書偉
• Other Authors: Hsin Yu
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/67966967247585437780

碩士 === 國立宜蘭大學 === 土木工程學系碩士班 === 103 === The average annual temperature increased year by year because of greenhouse effect in earth. The excessive use of fossil fuels causes more greenhouse gas which results in the climate change. The energy use is of 28.3 % the country total energy consumption, this many researches of renewable energy went conducted. The study designed a system of heat exchange between water and air (water-air heating exchange, WAHE) which induced the outdoor air passing through the WAHE with heat change to achieve the purpose of winter heating and summer cooling. This method of this study includes the use of WAHE to proceed heating study indoors, and winter heating and summer cooling outdoors. The factor impact system performances were simulation using theoretical analysis. This results of the indoor experiment and simulation show that the outlet temperature of WAHE is raised above 10 ℃ from the inlet temperature. The heat exchange effectiveness is between 67.5 % and 97.3 %. The decrease of the pipe length results in the decrease of outlet temperature the decrease of airspeed results in the increase of outlet temperature to decrease the diameter of pipe also results in the increase of outlet temperature the increase of pipe length and the decrease of airspeed and pipe diameter will increase the effectiveness of heat exchange. The pipe material influence the effect of WAHE insignificantly even the heat conductance is different in different pipe material. The results of outdoor experiment in winter showed that the air temperature were raised about 5 ℃ when the inlet temperature were between 14.8 ℃ to 15.7 ℃ and the outlet temperature were between 18 ℃ to 21.5 ℃ with mean water temperature of 21 ℃. The effectiveness of heat exchange was over 8 %, the average heating potential was 0.27 kW, and the daily heating capacity was 0.65 kWh. The results of outdoor experiment in summer showed that the air temperature were descended about 2.7 ℃ when the mean inlet temperature was 28.9 ℃ and the mean outlet temperature was 26.2 ℃ with mean water temperature of 23.9 ℃. The effectiveness was about 54 %, the average cooling potential was 0.28 kW, and the daily cooling capacity was about 0.7 kWh. This study provided the information of effectiveness of WAHE in field experiment and the impact factors of airspeed, pipe length, pipe diameter, and pipe material etc. using simulation. The results can contribute to the design of WAHE in the future.