Article

Comparative study of cycle performance for a two stage intermittent solar refrigerator working with R22-absorbent combinations

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Abstract

An analysis of the thermodynamic cycle for a two stage intermittent solar refrigerator is performed for R22-DMF, R22-NMP and R22-DMETEG. The effects of different parameters, like volume ratio, and high and low pressure stage initial concentrations on cycle performance are studied for these combinations. The comparison of cycle performances between these working fluids helps in selecting the best working fluid combination.

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... Dincer et al. [7] used a mixture of R-22 and dimethyl ether tetra ethylene glycol as the working fluid. The coefficient of performance (COP) for theory and experiment was found to be 0.6 and 0.4, respectively, at a generator temperature of 90 C. Das and Mani [8] recommended the use of R22-N,N-dimethyl formamide. Another attempt towards the improving of the performance of solar-driven absorption cycle is to improve the performance of the solar collection by using glazed collectors/ generators [9]. ...
... The concentrated rays, which fall onto the receiver results in high temperature of the central receiver is used to heat the oil (Duratherm 600). The oil is flowing through the pipes which transfer the thermal energy from central receiver to the HRVG (1-2) and generator (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). Superheated vapor of R141b (4) is expanded in a turbine to generate work. ...
... The mixed stream (6) is cooled in condenser-1 (C1). The saturated liquid (7) is divided into two parts (8,9), one part (9) is passed through throttling valve-1 (TV1) where pressure is reduced to evaporator pressure (10) and feed to E1, and second part (8) is pumped by pump-1 (P1) to the HRVG of RC cycle. The solar thermal energy (2) coming out from HRVG passes through the generator of ARC and finally recirculated to the central receiver. ...
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In this paper, energy and exergy analyses of a new solar-driven triple-staged refrigeration cycle using Duratherm 600 oil as the heat transfer fluid are performed. The proposed cycle is an integration of absorption refrigeration cycle (ARC), ejector (EJE) refrigeration cycle (ERC), and ejector expansion Joule-Thomson (EJT) refrigeration cryogenic cycles which could produce refrigeration output of different magnitude at different temperature simultaneously. Both exergy destruction and losses in each component and hence in the overall system are determined to identify the causes and locations of the thermodynamic imperfection. Several design parameters, including the hot oil outlet temperature, refrigerant turbine inlet pressure, and the evaporator temperature of ERC and EJT cycle are also tested to evaluate their effects on energy and exergy performance. It is observed that largest contribution to cycle irreversibility comes from the central receiver and heliostat field with the heat recovery vapor generator (HRVG), condenser, and ejector of ERC itself also contributing considerably. The exergy efficiency of the solar-driven triple-staged refrigeration cycle is 4% which is much lower than its energy efficiency of 10%, respectively. The results clearly reveal that thermodynamic investigations based on energy analysis alone cannot legitimately be complete unless the exergy concept becomes a part of the analysis.
... Another study was accomplished by Das and Mani [96] on a two stage intermittent solar refrigerator. They tried to find the best absorbent fluid that for the R22 refrigerant, which is a popular choice as refrigerant for its ozone friendliness (ODP¼0.05). ...
Article
SUMMARY This investigation is persuaded for the first and second law analyses of a new solar-driven triple-effect refrigeration cycle using Duratherm 600 oil (Duratherm Extended Life Fluid, NY, USA) as the heat transfer fluid is performed. The proposed cycle is an integration of ejector, absorption, and cascaded refrigeration cycles that could produce refrigeration output of different magnitude at different temperature simultaneously. Both exergy destruction and losses in each component and hence in the overall system are determined to identify the causes and locations of the thermodynamic imperfection. The effects of some influenced parameters such as hot oil outlet temperature, refrigerant turbine inlet pressure, and the evaporator temperature of ejector and cascaded refrigeration cycle have been observed on the first and second law performances. It is found that maximum irreversibility occurs in central receiver as 52.5% and the second largest irreversibility of 25% occurs in heliostat field. The second law efficiency of the solar driven triple effect refrigeration cycle is 2%, which is much lower than its first law efficiency of 11.5%. Analysis clearly shows that performance evaluation based on the first law analysis is inadequate and hence, more meaningful evaluation must be included in the second law analysis. Copyright © 2013 John Wiley & Sons, Ltd.
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Solar energy is one of the most efficient, clean and affordable energy alternatives available today. With the current concerns about global warming and ever increasing energy rates, countries are seriously looking for domestic and industrial usage of solar energy. In the present study, a detail review of the application of solar energy for refrigeration systems has been carried out. The utilization of solar energy for refrigeration systems would help in improvement of energy economics, energy consumption and energy efficiency. The review focuses especially on solar panel, desiccant fluid for icemaker and its components. The study also includes thermodynamic equation and material for making component of refrigeration to improve the coefficient of performance. Study around the economic evaluation and solar performance coefficient in the type of refrigerator, modeling and simulation, mathematical equation of heat transfer and type of absorption used are other topics that could be considered.
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A computer code has been developed for simulation of absorption systems in a flexible and modular form, which makes it possible to investigate various cycle configurations with different working fluids. The code is based on unit subroutines containing the governing equations for the systems's components. Those are linked together by a main program according to the user's specifications to form the complete system. The equations are solved simultaneously, and fluid properties are taken from a property database. The code is user-oriented and requires a relatively simple input containing the given operating conditions and the working fluid at each state point. The user conveys to the computer an image of his cycle by specifying the different subunits and their interconnection. Based on this information, the program calculates the temperature, flow rate, concentration, pressure, and vapor fraction at each state point in the system and the heat duty at each unit, from which the coefficient of performance may be determined. The program has been used successfully to simulate a variety of single-stage, double-stage, and dual-loop heat pumps and heat transformers, with the working fluids LiBr-H/sub 2/O, H/sub 2/O-NH/sub 3/, LiBr/H/sub 2/O-NH/sub 3/, LiBr/ZnBr/sub 2/-CH/sub 3/OH and more.
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