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ME312 Thermo Spring 2013 D. Abata ME312 Thermo II Design Project Format 1) Title, Name, Course Name and Number, Date (Top of Page) 2) Body (1 page) a) Background (What, Why) b) Project Description c) Approach d) Principal Results and Summative Information. 3) Tables, Charts, Drawings, Calculations and Data (5 Pages max!) Reports must be neat and submitted using a suitable word processor. Reports will be graded on a 100 pt basis and are worth 10% of your final grade. Reports are due Friday, April 26 at the beginning of class. Late penalty is 10% per day. 9-215 Exhaust gases from the turbine of a simple Brayton cycle are quite hot and may be used for other thermal pur- poses. One proposed use is generating saturated steam at 110°C from water at 30°C in a boiler. This steam will be distributed to several buildings on a college campus for space heating. A Brayton cycle with a pressure ratio of 6 is to be used for this purpose. Plot the power produced, the flow rate of produced steam, and the maximum cycle tem- perature as functions of the rate at which heat is added to the cycle. The temperature at the turbine inlet is not to exceed 2000°C. 10-140 Stack gases exhausting from electrical power plar are at approximately 150°C. Design a basic Rankine eye that uses water, refrigerant-134a, or ammonia as the workii fluid and that produces the maximum amount of work fro this energy source while rejecting heat to the ambient air 40°C. You are to use a turbine whose efficiency is 92 perce and whose exit quality cannot be less than 85 percent. Air enters the compressor of an ideal gas refrig- eration cycle at 7°C and 35 kPa and the turbine at 37°C and 160 kPa. The mass flow rate of air through the cycle is 0.2 kg/s. Assuming variable specific heats for air, determine (a) the rate of refrigeration, (b) the net power input, and (c) the coefficient of performance. Answers: (a] 15.9 kW, (b) 8.66 kW, (c) 1.84 Special: Build and analyze a Sterling Pop Can engine. For instance, see: http://www.youtube.com/watch?v=W9cK_TMLvjl The cost of the engine must not exceed a few dollars. Include with your report a video of your running engine not to exceed 3 minutes in length. 11-74 Repeat Prob. 11-73 for a compressor isentropic effi- ciency of 80 percent and a turbine isentropic efficiency of 85 percent. I n~75 [53 Reconsider Prob. 11-74. Using EES (or other) K^l software, study the effects of compressor and I turbine isentropic efficiencies as they are varied from 70 to : 100 percent on the rate of refrigeration, the net power input, and the COR Plot the T-s diagram of the cycle for the isen- tropic case. 15-142 A steam boiler is designed to convert saturated liq- uid water at 3500 kPa to steam at 3450 kPa and 400°C. This boiler burns natural gas (i.e., methane) at 1 atm and 25°C. Combustion air is also supplied at 1 atm and 25°C. The flow of combustion air is adjusted to maintain the temperature of the combustion products at 300°C. On a common basis of 1 kilogram of steam produced, calculate the change in the exergy of the combustion and water streams for excess air amounts ranging from 0 to 200 percent. Also calculate the exergy lost in this boiler as the excess air amount is varied. 11-151 Consider a solar pond power plant operating on a closed Rankine cycle. Using refrigerant-134a as the working fluid, specify the operating temperatures and pressures in the cycle, and estimate the required mass flow rate of refrigerant- 134a for a net power output of 50 kW. Also, estimate the sur- face area of the pond for this level of continuous power production. Assume that the solar energy is incident on the pond at a rate of 500 W per m2 of pond area at noontime, and that the pond is capable of storing 15 percent of the incident solar energy in the storage zone.
