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This paper experimentally analyzes thermal performance of an air-cooled type single effect absorption refrigeration cycle with ammonia–lithium nitrate and ammonia–sodium thiocyanate solutions as working pairs. Ammonia/salt system has simple construction, low evaporating temperature (

An absorption-ejection refrigeration cycle used R290-mineral oil mixture is investigated depending on both conventional and advanced exergy analysis. In this cycle, an ejector and an air-cooled type absorber are utilized to improve the exergetic efficiency of the system. The effects of generator temperature, condensing temperature, evaporating temperature, absorber outlet temperature, absorber efficiency, and pressure ratio on system exergetic efficiency have been discussed and compared with a single-effect absorption cycle in this study. Furthermore, the exergy destruction of each component has been calculated and analyzed. Besides, the exergy destruction of the major components are further researched through the advanced exergy analysis. Analytical results show that the absorption-ejection refrigeration cycle has a higher exergetic efficiency and a more extensive working condition range than the single effect absorption cycle and its exergetic efficiency can reach 0.3554. It is proved the R290/mineral oil as absorption refrigeration has great research value. In addition, the vast majority of exergy destruction appears in the generator and absorber, totally above 60%. The optimization of the generator has the highest priority due to its maximum endogenous avoidable exergy destruction. The absorber is in second place and its exergy destruction can be effectively reduced by optimizing other components.

A combined vapor power cycle (PC) and double effect water–LiBr absorption refrigeration system (ARS) is proposed in this study. The boiler leaving flue gas of the PC is the heat source for the high pressure generator (HPG) of the double effect ARS. Exergy analysis of the proposed system is performed to show the performance variation of both the topping PC and the bottoming ARS with changing HPG temperature from 120 °C to 150 °C. Further the performance of double effect ARS integrated combined power and cooling system is compared with a similar system integrated with a single effect ARS. HPG temperature of the double effect ARS and generator temperature of the single effect ARS are considered as 120 °C and 80 °C respectively. Results show that the power and efficiency of the topping PC decreases with HPG temperature due to reduction in steam generation rate in the boiler. COP and exergy efficiency of the double effect ARS also reduces with increasing HPG temperature. The irreversible losses in the PC components decrease while the total irreversibility of the combined power and cooling system increases with HPG temperature due to increase in exergy loss with the HPG leaving flue gas and irreversibility of the ARS components. PC performance does not vary much due to replacement of the double effect ARS with the single effect ARS, however higher COP and exergy efficiency of the double effect system are achieved with much lower irreversible losses in the HPG and ARS condenser of the double effect system.

In this paper a comparative study between single effect and double effect absorption refrigeration systems with identical cold output is carried out. Simulation results were used to study the influence of the various operating parameters on the performance coefficient, the thermal loads of the components, exergetic efficiency (rational efficiency) and the total change in exergy of the two systems. It is concluded that the COP of double effect system is approximately twice the COP of single effect system but the exergetic efficiency of double effect system increase slightly compared to the exergetic efficiency of single effect system. It is found that for each condenser and evaporator temperature, there is an optimum generator temperature where the total change in exergy of the single effect and double effect absorption refrigeration systems is minimum. At this point the COP and exergetic efficiency of the systems become maximum. In this study and when the evaporation temperature is varied from 4 °C to 10 °C, condenser and absorber temperatures are varied from 33 °C to 39 °C and generator (HPG) temperature is varied from 60 °C to 190 °C the maximum COP values of the single effect refrigeration systems are in the range of 0.73–0.79 and for double effect refrigeration systems are in the range of 1.22–1.42. The maximum exergetic efficiency values of the single effect refrigeration systems are in the range of 12.5–23.2% and for double effect refrigeration systems are in the range of 14.3–25.1%.

The effect of wind speed V on the daily productivity Pd of some active and passive solar stills is studied by computer simulation. Numerical calculations have been carried out on typical summer and winter days in Tanta in order to correlate Pd with V for different masses of basin water mw for the passive stills and various thicknesses dw or mass flow rates m w of the flowing brine for the active stills. It is found that for the active and multi-effect passive stills, Pd increases with the increase of V up to a typical velocity Vt beyond which the increase in Pd becomes insignificant. However, for all the investigated single effect passive stills, there is a critical mass (depth) of basin water beyond which Pd increases as V increases until Vt. For basin water masses less than the critical mass, Pd is found to decrease with increasing V until Vt. After Vt, the change in Pd is unimportant in a similar behavior to that obtained for the active and multi-effect passive stills. The critical mass (depth) of basin water for the investigated single effect passive stills is found to be 45 kg (4.5 cm). Moreover, the typical velocity Vt is independent on the still shape and the mode of operation (active or passive) but it shows some seasonal dependence. For the investigated stills, Vt is found to be 10 and 8 m/s on typical summer and winter days, respectively. Comparisons with the results reported in the previous studies about the effect of wind speed on productivity have been carried out.

In this communication, an analysis of a double effect, active solar distillation unit has been presented by incorporating the effect of climatic and design parameters. Based on an energy balance in a quasi-steady condition, an analytical expression for hourly yield for each effect has been derived. Numerical computations have been carried out for a typical day in Delhi, and the results have also been compared with single effect, active solar distillation unit. It has been observed that there is a significant improvement in the performance for a minimum flow rate of water in the upper basin.