Study on Using the Ground as A Heat Sink for A 12,000-Btu/h Modified Air Conditioner

Authors: W. Permchart, S. Tanatvanit

Abstract:

This paper presents the results of the experimental tests of the cooling performance of a 12,000-Btu/h modified air conditioner (referred to as M-AC) that use the ground as a heat sink of a condenser. In the tests, cooling capacity of M-AC with an optimal length of a condensing coil as well as life expectancy of copper coil buried underground were investigated. The lengths of copper coil fabricated and used as condenser coil of M-AC were set at 67, 50, 40 and 30 m whereas that of a 12,000-Btu/h conventional split-type air conditioner (referred to as C-AC) was about 22 m. The results showed that the ground can absorb heat rejected from a condenser of M-AC. The coefficient of performance (COP) of C-AC was about 2.5 whereas those of M-AC were found to be higher. It was found that the values of COP of M-AC with condensing coils of 67, 50 and 40 m long were about 6.9, 5.5 and 3.3, respectively, while that of 30-m-long one was found to be about 2.1. The electrical consumptions of M-AC were found lower than that of C-AC in the range of 11.5 – 15.5%. Additionally, life expectancy of underground condensing coil of M-AC was found to be over 7 years.

Keywords: Air conditioner, condenser, copper coil, ground.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1057545

References:

[1] M.A. Odey, "Use of Seawater as Condenser Coolant on Large Coolstore Refrigeration System," in 1993 Proc. of Commissions: Cold Chain Refrigeration Equipment by Design, pp. 23-31.
[2] R. Ladislaus and S. Burkhard, "Ground-source Heat Pump Systems The European Experience," GHC Bulletin, March 2000, pp. 16-26.
[3] B. Givoni, and L. Katz, "Earth Temperatures and Underground Building," Energy and Building, Vol. 8, March 1985, pp.15-25.
[4] Sound Geothermal Corperation, Roosevelt, USA (2004, August). Available: http://www.soundgt.com/index.html
[5] FHP Manufacturing Inc., Ft. Lauderdale, USA (2004, June). Available: http://www.fhp-mfg.com/
[6] Maritime Geothermal Ltd., New Brunswick, Canada (2002, March). Available: http://www.discribe.ca/nordic/mgmain.htm
[7] S. S. Bharadwaj, and N. K. Bansal, "Temperatures Distribution inside Ground for Various Surface Conditions," Building and Environment, Vol.16, March 1981, pp. 183-192.
[8] A.K. Khatry, M.S. Sodha and M.A.S. Malik, "Periodic Variation of Ground Temperature with Depth," Solar Energy, Vol. 20, May 1978, pp. 425-427.
[9] M. Santamouris, G. Miharakakou, A. Argirious, and D. Asimakopoulos, "On the Performance of Buildings Coupled with Earth to Air Heat Exchanger," Solar Energy, Vol. 54, June 1995, pp. 375-380.
[10] C. Changprai, Soil Climate, Dept. of Land Development, Ministry of Agriculture and Cooperation, Bangkok, 1987.
[11] J. Khedari, W. Permchart, N. Pratinthong, S. Thepa, and J. Hirunlabh, "Field Study Using the Ground as a Heat Sink for the Condensing Unit of an Air Conditioner in Thailand," Energy, Vol. 26, August 2001, pp. 797-810.
[12] F. P. Incropera, and D. P. Dewitt, Fundamentals of Heat and Mass Transfer, John Wiley and Sons, New York, 2002.
[13] Y. A. Cengel, and M. A. Boles, Thermodynamics: An Engineering Approach, McGraw-Hill, New York, 2000.