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View Full Version : another heat engine efficiency problem


kbyws37
Feb14-07, 06:27 PM
A reversible heat engine has an efficiency of 34.2%, removing heat from a hot reservoir and rejecting heat to a cold reservoir at 0°C. If the engine now operates in reverse, how long would it take to freeze 1.10 kg of water at 0°C, if it operates on a power of 183 W?



I am getting stuck on how I can incorporate the kg of water and the power.
I don't know which equation to use that will let me use those constants and allow me to find time.

hage567
Feb14-07, 10:06 PM
Well, to freeze water, you have to remove thermal energy from it. How do you find the amount of energy needed to be removed for a phase change of the water at 0°C to ice at 0°C?
It gives you the power the engine is operating at. What is the definition of power?
I'd think about those things to start.