Chapter 1 Basics of Heat Transferwhere kW4.17kJ/h15,000kW4kJ/h 400,14kJ/h36040kW1W10010gainheatpeoplelights====×==×=QQQ&&&Substituting, &.Qcooling9.17 kW=++=14417Thus the number of air-conditioning units required is units283.1kW/unit5kW9.17⎯→⎯=1-27EThe air in a rigid tank is heated until its pressure doubles. The volume of the tank and the amount of heat transfer are to be determined. Assumptions1 Air is an ideal gas since it is at a high temperature and low pressure relative to its critical point values of -141°C and 3.77 MPa. 2 The kinetic and potential energy changes are negligible, . 3Constant specific heats at room temperature can be used for air. This assumption results in negligible error in heating and air-conditioning applications. ΔΔpeke≅≅0Properties The gas constant of air is R = 0.3704 psia.ft3/lbm.R = 0.06855 Btu/lbm.R (Table A-1). Analysis(a) We take the air in the tank as our system. This is a
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This note was uploaded on 01/14/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.