Evaluation of Outside Air Design Dry and Wet Bulb Temperatures for Air Conditioning Systems in Nigeria

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Date

2015-06

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Publisher

The Nigerian Society of Engineers

Abstract

There is increase in the ambient temperature being experienced around the world due to global warming and this has caused the energy consumption of cooling systems to increase. Statistical analysis was carried out on meteorological data obtained from Nigerian Meteorological Agency for 18 towns in Nigeria for 1994 - 2008 or 1995 - 2009. The weather variables considered in this study were hourly relative humidity and dry bulb temperature, three hourly wet bulb temperature and vapour pressure. The averages of dry bulb temperature, wet bulb temperature and vapour pressure were computed. The four warmest months were determined for each location, from which the outdoor 1 %, 2.5 %, and 5 % design conditions of dry bulb temperature, wet bulb temperature and vapour pressure were computed using Normal Distribution tables for each town. The design month is the month with the highest average maximum temperature. The following design months were obtained from the results: February is the design month for Benin City, Calabar, Ibadan, Ondo, Owerri and Port Harcourt; March for Abuja, Enugu, Ikeja, Ilorin, Jos and Minna, April for Bauchi, Kaduna, Kano, Maiduguri, Sokoto and Yola. The 21/2 % outside design dry bulb and wet bulb temperatures obtained for 1951 - 1965 by earlier workers were compared with those obtained for 1994 - 2009 in this work. The percentage differences obtained were 13 - 25 % for dry bulb design temperature and from 2 - 40 % for wet bulb temperature. It was concluded that climate change has caused outside design conditions for air conditioning systems to change and results obtained in this work should be used to replace the design conditions formerly used by engineers which were obtained from earlier periods. This work is useful in preparing a revised code of practice for comfort air conditioning system design for Nigeria.

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Keywords

Air conditioning, Dry bulb temperature, Wet bulb temperature, Relative humidity, Global warming

Citation

Olorunmaiye, J. A., & Awolola, O. O. (2015). Evaluation of Outside Air Design Dry and Wet Bulb Temperatures for Air Conditioning Systems in Nigeria. NSE Technical Transactions: Journal of the Nigerian Society of Engineers, 49(2), 54–66.

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