robertbob Posts: 1, Reputation: 1 New Member   #1 Apr 21, 2003, 06:04 PM

Basic Thermodynamics Hi, I am a 2nd year mechanical engineering student in Turkey. This semester I am having Thermodynamics I. Our instructor gave us a number of assignments but we don't know where to begin. We asked for some help but he told us to make some studies and find the answers... Like I said, we don't know where to begin at all, so if anyone could help me in these questions, I would really appreciate it; 1. Using information from the utility bills for the coldest month last year, we are to estimate the average rate of heat loss from our house for that month. In our analysis we are supposed to consider the contribution of the internal heat sources as people, lights, and appliances. We are to identify the primary sources of heat losses from our house, and propose ways of improving the energy efficiency of our house. 2. We are to design a reciprocating compressor capable of supplying compressed air at 800 kPa at a rate of 15 kg/min. Also we need to specify the size of electric motor capable of driving this compressor. The compressor is to operate at no more than 2000 rpm (revolutions per minute) 3. We are asked to design a heating system for a swimming pool that is 2-m-deep, 25-m long, and 25 m-wide. Our client desires that the heating system be large enough to raise the water temperature from 20 C to 30 C in 3 h. The rate of heat loss from the water to the air at the outdoor design conditions is determined to be 960 W/m^2, and the heater must also be able to maintain the pool at 30 C at those conditions. Heat losses to the ground are expected to be small and can be disregarded. The heater considered is a natural gas furnace whose efficiency is 80 percent. We need to recommend an appropriate heater size to our client ? 4. A 1982 U.S. Department of Energy article states that a leak of one drip of hot water per second can cost $1.00 per month. Making reasonable assumptions about the drop size and the unit cost of energy, we are todetermine if this claim is reasonable. 5. We are to write a computer program to express the variation of specific heat Cp of air with Temperature as a third- degree polynomial, using the data in Table A-2b, in our book. This table gives various Cp's for air at different temperature. I couldn't understand how the program is supposed to express the variation of Cp's with temperature as a third degree polynomial... Thanks in advance... Bob

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