Performance optimization of transcritical CO2 cycle with parallel compression economization

Sarkar, Jahar; Agrawal, Neeraj

doi:10.1016/j.ijthermalsci.2009.12.001

Cited by 92 publications

(52 citation statements)

References 9 publications

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“…In this second solution the surplus of the gaseous component is conveyed to the liquid-gas separator by means of the differential valve, while the liquid is carried into a second electronic expansion valve (EEV) based on a PWM control (Pulse Width Modulation). The last solution leads to a higher COP in double expansion than in a single (traditional) one [8,11,14,15,22,27]. Moreover, it is widely recognized that the optimal working condition of electronic expansion valves is achieved when only the liquid phase enters the valve: avoiding flash gas at the inlet of the valve, not only is the best working efficiency guaranteed due to a correct and homogeneous lamination, but also an increase in the service life.…”

Section: Basic Experimental Co2 Plantmentioning

confidence: 99%

“…[8][9][10]. The subcritical refrigeration cycle (Figure 1a) is comparable to that of other fluids; it is widely used as a low temperature one in cascade plants, while the primary one generally works with ammonia or R134a [11][12][13][14][15][16]. In plants that work with transcritical cycle, at high pressure heat exchanger outlet, the liquid CO2 is separated from the gaseous one and conveyed to the expansion devices, while the steam part, named flash gas, is recovered and conveyed by the compressor suction (Figure 1b) [10,[16][17][18].…”

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confidence: 99%

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CO2 Employment as Refrigerant Fluid with a Low Environmental Impact. Experimental Tests on Arugula and Design Criteria for a Test Bench

et al. 2015

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Abstract:In order to define design criteria for CO2 refrigeration systems to be used for agricultural products and foodstuff storage, a variable geometrical system was realized, with the goal of meeting a wide range of environmental and process conditions, such as producing low environmental impact and maintaining the highest Coefficient of Performance (COP), at the same time. This test-bench, at semi-industrial scale, was designed as a result of experimental tests carried out on Arugula. The storage tests showed that all samples stored in cold rooms with R.H. control showed a slight increase of weight but also small rot zones in all the boxes due to an excessive accumulation of water condensation; thus, the system may not have achieved conditions that RH requires in a given range, without reaching saturation condition. At the same time, the use of CO2 must be adequately tested along its thermodynamic cycle, during steady state and/or transient conditions, imposing OPEN ACCESSSustainability 2015, 7 3735 variable working conditions that can simulate plant starting phase or some striking conservation process, like those that characterize sausages. The designed plant will allow studying these specific performances and evaluate COP variation, according to environmental and plant operating conditions.

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Section: Basic Experimental Co2 Plantmentioning

confidence: 99%

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confidence: 99%

CO2 Employment as Refrigerant Fluid with a Low Environmental Impact. Experimental Tests on Arugula and Design Criteria for a Test Bench

et al. 2015

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“…In particular, Sarkar and Agrawal [16] implemented a theoretical study on various parallel compression-based R744 refrigeration systems. The authors concluded that the solution investigated in this study is the most promising solution.…”

Section: Introductionmentioning

confidence: 99%

“…According to Javerschek et al [17] and Gullo et al [8], the transcritical R744 refrigeration systems outfitted with parallel compression are defined as the current benchmark (as well as the 2 nd generation) of "CO2 only" refrigerating units for supermarket applications. As a consequence, many theoretical and experimental efforts are being devoted to the evaluation the performance of such a solution [10,[16][17][18][19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Performance Assessment of a CO2 Supermarket Refrigeration System with Auxiliary Compression Economization by using Advanced Exergy Analysis

Gullo

Hafner

2017

International Journal of Thermodynamics

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Supermarkets are currently one of the most vital service facilities, whose number of installations is ever-growing in both developed and developing countries. On the other hand, these applications feature a copious indirect contribution to the ongoing climate change, as well as a massive use of potent greenhouse gases. In an attempt to promote climatefriendlier technologies in commercial refrigeration sector, "CO2 only" (transcritical CO2 or pure CO2) refrigeration systems have become the mainstream of new food retails worldwide. In particular, in the last few years parallel (or auxiliary) compression has taken root in food retails as a means to enhance the energy efficiency of pure CO2 units. The thermodynamic performance of such a promising solution can be suitably assessed with the aid of the advanced exergy analysis. The results obtained at the design outdoor temperature of 40 °C showed that the main compressor has the highest priority of enhancement, whereas the high-pressure expansion valve needs to be replaced with a device for expansion work recovery. Also, close attention had to be paid to both the gas cooler and the auxiliary compressor. The former can be improved mainly by enhancing the other components, whereas the irreversibilities related to the latter can be decreased by improving both the compressor itself and the remaining components. Finally, the implemented sensitivity analysis revealed that the improvement in the efficiency of the main compressor should be seriously considered on the part of the manufacturers.

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“…Zha et al [5] introduced a Voorhees compressor in CO 2 heat pump economizer cycle and compared with the traditional screw or scroll economizer cycles, and experimentally showed the superior performance. Sarkar [6] has done the thermodynamic analysis and optimization of transcritical CO 2 cycle with parallel compression economization for air-conditioning applications and showed significant COP improvement and optimum discharge pressure reduction over basic expansion cycle. However, any theoretical or experimental studies on other natural refrigerants-based refrigeration cycle with parallel compression economization are scarce.…”

Section: Introductionmentioning

confidence: 99%

Performance characteristics of refrigeration cycle with parallel compression economization

Sarkar

2010

Int. J. Energy Res.

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SUMMARYThermodynamic analyses and economizer pressure optimizations of ammonia, propane and isobutane-based refrigeration cycles with parallel compression economization are presented in this article. Energetic and exergetic performance comparisons with transcritical CO 2 cycle are presented as well. Results show that the optimum economizer mass fraction as well as COP improvement increase with increase in cycle temperature lift. The expression for optimum economizer pressure has been developed. Study shows that the performance improvements using parallel compression economization are strongly dependent on the refrigerant properties as well as the operating conditions. Using parallel compression economization, carbon dioxide yields maximum COP improvement of 31.9% followed by propane (29.8%), isobutane (27.2%) and ammonia (11.3%) for studies ranges. In spite of higher COP improvement, the cooling COP as well as second low efficiency for carbon dioxide is still significantly lower than that for others. Component-wise irreversibility distributions show the similar trends for all refrigerants except CO 2 . Employing parallel compression economization in refrigeration cycle not only improves the cooling COP but also increase the compactness of evaporator.

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Performance optimization of transcritical CO2 cycle with parallel compression economization

Cited by 92 publications

References 9 publications

CO2 Employment as Refrigerant Fluid with a Low Environmental Impact. Experimental Tests on Arugula and Design Criteria for a Test Bench

CO2 Employment as Refrigerant Fluid with a Low Environmental Impact. Experimental Tests on Arugula and Design Criteria for a Test Bench

Thermodynamic Performance Assessment of a CO2 Supermarket Refrigeration System with Auxiliary Compression Economization by using Advanced Exergy Analysis

Performance characteristics of refrigeration cycle with parallel compression economization

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