ABSTRACT
Renewable cooling via absorption chillers being supplied by various green heat technologies such as solar collectors has been widely studied in the literature, but it is still challenging to get positive economic outcomes from such systems due to the large expenses of solar thermal systems. This study offers the use of a new generation of solar collectors, so-called eccentric reflective solar collectors, for driving single-effect absorption chillers and thereby reducing the levelized cost of cooling. This article develops the most optimal design of this system (based on several different scenarios) using multi-objective optimization techniques and employs them for a case study in Brazil to assess its proficiency compared to conventional solar-driven cooling methods. For making the benchmarking analyses fair, the conventional system is also rigorously optimized in terms of design and operation features. The results show that the eccentric solar collector would enhance the cost-effectiveness by 29%. In addition, using optimally sized storage units would be necessary to get acceptable economic performance from the system, no matter which collector type is used. For the case study, at the optimal sizing and operating conditions, the levelized cost of cooling will be 124 USD/MWh and an emission level of 18.97 kgCO2/MWh.
Subject(s)
Solar Energy , Sunlight , Cold Temperature , Hot Temperature , Phase TransitionABSTRACT
Solar still, as one of the important devices for generating water using renewable energy, has been widely used in arid as well as coastal areas where access to fresh water is limited. This paper uses CFD simulation to compare double-slope solar still, hemispherical solar still, and tubular solar still using nanofluid film cooling. Al2O3-water nanofluids with a concentration of 0.1% are used due to facilitate sunlight penetration into the absorber plate inside the solar desalination. It is assumed the flow is steady, laminar, and air is an ideal and incompressible gas. The simple algorithm is considered to calculate the relationship between pressure and velocity and to separate the transfer and pressure interpolation terms from the appropriate upstream designs. Also, the economic, exergoeconomic, and CO2 mitigation parameters of various solar stills were investigated. The study revealed that the water productivity of double-slope solar desalination using nanofluids film cooling is improved by about 4.8% compared with tubular solar desalination with nanofluid film cooling. Also, the lowest CPL of 0.0362 $/L was obtained in the double-slope solar desalination using nanofluid film cooling. The net CO2 mitigation of 14.08 tons, 13.72 tons, and 13.44 tons was obtained for double-slope solar desalination, hemispherical solar desalination, and tubular solar desalination, respectively.
ABSTRACT
The present study aims to investigate the performance of a one-stage thermoelectric cooler using mathematical and thermodynamic modeling and proposing a new correlation for performance evaluation of a thermoelectric cooler combined with two heatsinks. Validating the results of the proposed correlation, a series of experiments have been carried out on the same system. The system consists of a thermoelectric cooler and a heatsink on each side. Deriving the governing equations of the system, the effects of changing the voltage and the thermal resistance of the cold- and hot-side heatsink on cooling power, the cold-side temperature of thermoelectric, and the coefficient of performance of the system have been investigated. The results indicated that changes in voltage have a considerable effect on the performance of the system. Moreover, the maximum cooling power of the system takes place at the voltage of 14 V, which is the optimum voltage of the system. Furthermore, decreasing the thermal resistance of the hot-side heatsink leads to increasing the cooling power and the cold-side temperature of the thermoelectric cooler. On the other hand, increasing the thermal resistance of the cold-side heatsink leads to decreasing the cooling power of the system.
