Local stability of a non-endoreversible Carnot refrigerator working at the maximum ecological function

Local stability of a non-endoreversible Carnot refrigerator at the maximum ecological function is studied with Newton's heat transfer law between working fluid and heat reservoirs. The steady state of the refrigerator working at the maximum ecological function is steady. It is derived that a general expression of relaxation time described as stability of the system refers to heat capacity C, total heat exchange area F, temperature ratio of heat reservoirs tau, the degree of internal irreversibility phi, heat transfer coefficients alpha and beta. Distributing information of phase portraits of system is obtained. The results can provide some theoretical guidelines for the designs of practical refrigerator. (C) 2014 Elsevier Inc. All rights reserved.