Refrigeration 0.0 / 5 ? EngineeringEquilibrium ThermodynamicsUniversityNone Created by: OmololaS15Created on: 31-12-18 14:10 What is refrigeration? Work is transferred into heat and heat is transferred from cold object to a hot object. 1 of 17 Define the Coefficient of performance COP = |q_cold|/|w| 2 of 17 Give an equation for maximum coefficient of performance COP = |q_cold|/|w_min| = T_cold/T_hot -T_cold 3 of 17 What is free energy? The remaining energy stored in matter that is accessible. (G/A) 4 of 17 Give the key equation for Gibbs free energy and when is it valid? G =H -TS (constant pressure systems) 5 of 17 Give the key equation for Helmholtz free energy and when is it valid? A = U -TS (constant volume systems) 6 of 17 What is the key equation involving U,T,S,P.V ? dU =TdS -PdV 7 of 17 What is the key equation involving A,T,S,P.V ? dA = -SdT -PdV 8 of 17 What is the key equation involving H,T,S,P.V ? dH =TdS +VdP 9 of 17 How is Gibbs free energy modelled when T is constant? (∂G/∂P)_T = V ] from dG =Vdp -SdT 10 of 17 How is Gibbs free energy modelled when P is constant? (∂G/∂T)_P = -S ] from dG =Vdp -SdT 11 of 17 Define chemical potential The work required to add a particle of a substance to another. 12 of 17 Give an equation for chemical potential. μ_i = (∂G/∂n_i)_P,T,n_j [for pure substance μ=G_m --> molar Gibbs function] 13 of 17 Describe free energy The driving force to equilibrium,tells us what can happen. 14 of 17 What is a meta-stable state? A stste that is long-lived but not the most stable thermodynamically (local minimum) 15 of 17 What is Hess's law as applied to Gibbs free energy? Δ_r*G。 = Σ v_i Δ_f*G_i。 16 of 17 What is the free energy from undercooling? ΔG = (T_fus -T) * L/T_fus ] where L = ΔH=Δ_fus*H 17 of 17
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