Chapter 1 Basics of Heat Transfer1-31A student living in a room turns his 150-W fan on in the morning. The temperature in the room when she comes back 10 h later is 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. 4 All the doors and windows are tightly closed, and heat transfer through the walls and the windows is disregarded.ΔΔkepe≅≅0Properties The gas constant of air is R = 0.287 kPa.m3/kg.K (Table A-1). Also, Cp= 1.007 kJ/kg·K for air at room temperature (Table A-15) and Cv= Cp– R= 0.720 kJ/kg·K. Analysis
This is the end of the preview. Sign up
access the rest of the document.