THE JOURNAL OF KMUTNB Volume 31, No. 04, Month OCTOBER, Year 2021, Pages 624 - 637
Applications of an earth-air heat exchanger system for temperature and humidity control in a pleurotus sajor-caju mushroom house
Preecha Tummu, Tanakorn Kongbang, Komsan Mulper, Weerachart Kongthawee
Abstract Download PDFThe purpose of this research is to study the application of an earth-air heat exchanger system to control temperature and humidity in a Pleurotus aajor-caju mushroom house. Firstly, this research conducted measurements of underground temperatures at three depth levels for three soil groups in Udon Thani. Secondly, the calculation of the earth-air heat exchanger system was implemented for a 2.25 m × 2.25 m and 2.4 m high mushroom house and the real system was constructed. Finally, experiments on the performance test of the system were conducted, including mushroom cultivation experiments. The results of this research show that the underground temperature in Udon Thani is around 27–30°C and is a great potential use for the earth-air heat exchanger system at 1.5–2 m deep. The performance test of the system shows that the temperature can be reduced by 5°C from ambient temperature during warm temperature in the daytime. At the air supply speed of 5.4 m/s and underground temperature at 29°C, the mushroom house temperature can be reduced by 4°C, and the temperature gap between the air supply outlet and the underground was only 0.5°C because the air supply speed possesses the highest heat transfer rate. After installing a fogging system, including an automatic control system, the system can maintain relative humidity in the mushroom house above 80 percent, which is suitable for mushroom cultivation. Apart from that, the cultivation test of 400 mushroom cubes was conducted in the mushroom house compared with a traditional mushroom house. It is found that mushroom quantity received is higher than that of the cultivation in the conventional mushroom for 23 percent. However, it is reduced to 12 percent when considering installation cost of the underground temperature system. In conclusion, the use of the earth-air heat exchanger system with the mushroom house can help farmers in mushroom cultivation during the off-season.