Optimum operating conditions of solar driven heat engines

Conference · Wed Jul 01 04:00:00 UTC 1998

OSTI ID:20000176

Sahin, A Z

Formulating and solving problems of optimal process and optimization efforts through availability analysis, entropy generation minimization, finite-time thermodynamics, and thermoeconomics are among the fields of modern thermodynamics attracting considerable amount of attention. An application of these appears in the generation and thermodynamic optimization of mechanical or electrical power using solar driven heat engines. Radiation heat transfer plays a key role in the collector-ambient heat loss mechanisms. An optimal design can be found on a model of endoreversible heat engine considering the irreversibilities due to radiation heat transfer. Finite time thermodynamics analysis of heat engines were usually restricted to systems having either linear or power law heat transfer dependence to the temperatures of both reservoirs and engine working fluid. However, radiation and convection modes of heat transfer are often coupled and play a collective role in processes of heat engine. Investigation of this collective role is the primary objective of the present study. Heat transfer from hot reservoir is assumed to be radiation dominated, while convection heat transfer is assumed to be the main mode of heat transfer to low temperature reservoir. The irreversibilities due to these finite rate heat transfer were considered in determining the limits of efficiency and power generation which were discussed through varying process parameters. It is shown that Curzon-Ahlborn efficiency is not a fundamental upper limit on the efficiency of cyclic heat engines operating at maximum power conditions. This upper limit is a function of both the functional temperature dependence of heat transfer and relevant system parameters.

• Research Organization: King Fahd University of Petroleum and Minerals, Dhahran (SA)
• OSTI ID: 20000176
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
OPTIMIZATION
POWER GENERATION
SOLAR HEAT ENGINES
THERMODYNAMICS