Heat engines 0.0 / 5 ? EngineeringEquilibrium thermodynamicsUniversityNone Created by: OmololaS15Created on: 31-12-18 13:58 What do heat engines do? They convert heat into mechanical work which is represented by the transfer of heat by two bodies/reservoirs. 1 of 8 Give an equation that represents conservation of energy q_hot +q_cold +w = 0 2 of 8 What are the conventions for q_hot and q_cold q_hot<0 ; q_cold>0 3 of 8 Give the equation for the entropy of the universe when no work is extracted ∆S_univ = q_hot/T_hot + q_cold/T_cold 4 of 8 Define the heat engine efficiency The work out per unit heat ] η = -w/q_hot 5 of 8 When does the maximum work occur? When the system is reversible So when ∆S_univ = 0 6 of 8 What is the relationship between q_hot, q_cold, T_cold and T_hot in a reversible system? q_cold/q_hot = -T_cold/T_hot 7 of 8 State the equation for the maximum efficiency η_max = q_hot +q_cold/q_hot= 1+ q_cold/q_hot = 1- T_cold/T_hot 8 of 8
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