Theoretical analysis of producing cooling and power using solar thermal energy

الملخص EN

Theoretical analysis of producing cooling and power with the energy obtained from low-temperature as thermal resource is presented in this work.

This resource can be obtained from concentrating solar thermal energy (parabolic trough).

This system belongs to the broader class of low temperature, Rankine cycles which have been shown to be one of the most effective means for utilizing low temperature resources.

They have been applied to the production of mechanical power using heat from solar.

The system uses thermal energy in a low-temperature boiler to partially boil working fluid mixture (aqua-ammonia).

An ammonia rich vapor is produced, that drives an expander.

The expander’s output is mechanical power ; however, under certain operating conditions its exhaust can be cold enough to be used for cooling.

This possibility is the focus of the present work through solar energy analysis.

The theoretical study is presented which identifies expander inlet conditions, expander efficiency, and exhaust pressure as the factors determining exhaust temperature.

Estimated expander efficiencies are based on a consideration of the operating conditions and a review of current technology.

Preferred inlet conditions are identified ; however, they are linked to the overall operation of the cycle, as absorption pressure.

An optimal balance between vapor generation and expander exhaust temperature is found for cooling production.

The present coefficient of performance is defined as the ratio of the cooling gained to the work output lost and is used to determine the optimal purification of the vapor.

Therefore, another performance coefficient is defined and used to judge the overall value of cooling produced.

It is concluded that the proposed system improves the expander performance, output power and cooling production and can be satisfied with this concept.

More possible applications for this cycle may include those where cooling is not a primary output, but it is used to improve overall efficiency.