Abstract
The main objective of the present study is to investigate the performance characteristics of an underground air tunnel (UAT) for greenhouse heating with a 47 m horizontal, 56 cm nominal diameter U-bend buried galvanized ground heat exchanger. This system was installed in the Solar Energy Institute, Ege University, Izmir, Turkey. Based upon the measurements made in the heating mode, the average heat extraction rate to the soil is found to be 3.77 kW, or 80.21 W/m of tunnel length, while the required tunnel length in meters per kW of heating capacity is obtained as 12.46. The entering air temperature to the tunnel ranges from 14.3 to 21.5 °C, with an average value of 15.5 °C. When the system operates, the greenhouse air is at a minimum day temperature of 13.1 °C with a relative humidity of 32%. The maximum heating coefficient of performance of the UAT system is about 6.42, while its minimum value is about 0.98 at the end of a cloudy and cold day and fluctuates between these values at other times. The daily average maximum COP values for the system are also obtained to be 6.42. The total average COP in the heating season is found to be 5.16.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
