Applied ThermalEngineeringVol. 16, Nos 819, pp. 669475, 1996 zyxwvutsrqpo Pergamon 1359-4311(95)00079-8 Copyright 0 1996 Elsevier Science Ltd Printed in Great Britain. All rights reserved 1359-4311/96 $15.00 + 0.00 MATHEMATICAL SIMULATION OF A SOLAR EJECTOR-COMPRESSION REFRIGERATION SYSTEM R. Dorantes,* C. A. Estradat and I. Pilatowskyt *Departamento de Energia, UAM-A, Av. San Pablo, No. 180, 02200, Mexico; and TLaboratorio de Energia Solar, IIM-UNAM, Ap. 34, 62580 Temixco, Morelos, Mexico (Received 7 November 1995) Abstract-This paper presents a mathematical simulation for the dynamic thermal behavior of a solar ejector-compression refrigeration system with a capacity production of 100 kg of ice per day. It consists of an evacuated tube solar collector array, a thermal storage unit and an ejector-compression refrigeration unit. Due to the change in climate, the collector efficiency varies and, therefore, so does the system efficiency. This fact makes it necessary to evaluate the design of the system not just for a whole day but also for a whole year. The ejector-compression refrigeration system was designed to work with Freon Rl42b as the working fluid at condenser temperature (Z) of 3O”C,generation temperature (TG) of 105°C evaporator temperature (2-r) of - 10°C with a required generator heat load (Qo) of 5.6 kW and an obtained evaporator heat load (QE) of 2 kW, the corresponding COP was 34%. With these conditions, the ejector geometry was fixed and curves for Qo, QE and COP as a function of TCand TGwere obtained. A plot of the daily history of system storage tank temperature for two days of the year (one in January and one in June) is presented. Also graphs for the monthly average ice production, COP, collectors and system efficiencies are presented. The annual average values for COP, collector efficiency and system efficiency were 0.21, 0.52 and 0.11, respectively. Copyright 0 1996 Elsevier Science Ltd Keywords-Refrigeration; solar collectors; ejector-compression cycle; simulation. NOMENCLATURE AC solar collector array area, m* CP storage fluid heat capacity, J/kg-C FR collector heat removal factor, dimensionless G, solar radiation, W/m* h enthalpy m’ primary mass flow rate, kg/s m” secondary mass flow rate, kg/s PI- heat flow rate that is lost from the storage unit to the surroundings, Watts & heat flow rate that comes from the solar collector array, Watts heat flow rate that goes to drive the refrigeration unit, Watts I temperature, “C UL collector overall loss coeflicient, W/m*-K Greek letters W) effective transmittance absortance product, dimensionless Subscripts : ambient condenser f” evaporator freon G generator zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA S storage INTRODUCTION Solar-powered refrigeration systems based on the use of ejectors have been proposed and shown to be competitive with absorption- and Rankine-cycle-powered vapor-compression systems. An ejector refrigeration cycle is schematically shown in Fig. 1. The cycle consists of two sub-cycles. The power sub-cycle (6)-(l)-(3)-(4)-(6), defined by the part of the flow through the generator, operates between the thermodynamic states of the generator and condenser and generates the motive stream for compression. The refrigeration sub-cycle (5)-(2)-(3)-(4)-(5), defined by the flow through the evaporator, operates between the evaporator and the condenser. The pump is the only 669