Advanced Exergetic Assessment of a Vapor Compression Cycle With Alternative Refrigerants

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Nishant Modi ◽  
Bhargav Pandya ◽  
Jatin Patel ◽  
Anurag Mudgal
Keyword(s):  
Performance Improvement ◽  
Thermal Performance ◽  
Thermal System ◽  
Vapor Compression ◽  
Exergy Destruction ◽  
Alternative Refrigerants ◽  
The Real ◽  
Vapor Compression Cycle ◽  
Compression Cycle ◽  
Exergy Method

The present study compares the thermal performance of various alternative refrigerants with conventional refrigerant operating on a vapor compression cycle with energetic, exergetic, and advanced exergetic approaches. Appropriate alternative refrigerants are selected for the analysis, and R1234yf is recommended as the best suitable refrigerant to replace the existing refrigerants. By splitting the exergy destruction into endogenous and unavoidable, endogenous and avoidable, exogenous and unavoidable, and exogenous and avoidable parts, an advanced exergy method depicts the real potentials for the improvement in the thermal system. Moreover, a traditional exergy method prefers condenser for performance improvement as it has 18.48% higher exergy destruction than evaporator, whereas the advanced exergy method proposes evaporator rather than condenser since its endogenous and avoidable destruction part is 26.38% more than condenser for R1234yf refrigerant.

scholarly journals Thermodynamic analysis of a new dual evaporator CO2 transcritical refrigeration cycle

2017 ◽  
Vol 38 (1) ◽  
pp. 39-62 ◽  
Author(s):  
Ezzaalouni Yathreb Abdellaoui ◽  
Lakdar Kairouani Kairouani
Keyword(s):  
Performance Improvement ◽  
System Performance ◽  
Refrigeration Cycle ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Vapor Compression Cycle ◽  
Compression Cycle ◽  
Thermodynamic Performance ◽  
Effective System ◽  
Exergetic Analysis

AbstractIn this work, a new dual-evaporator CO2transcritical refrigeration cycle with two ejectors is proposed. In this new system, we proposed to recover the lost energy of condensation coming off the gas cooler and operate the refrigeration cycle ejector free and enhance the system performance and obtain dual-temperature refrigeration simultaneously. The effects of some key parameters on the thermodynamic performance of the modified cycle are theoretically investigated based on energetic and exergetic analysis. The simulation results for the modified cycle indicate more effective system performance improvement than the single ejector in the CO2vapor compression cycle using ejector as an expander ranging up to 46%. The exergetic analysis for this system is made. The performance characteristics of the proposed cycle show its promise in dual-evaporator refrigeration system.

A Model Predictive Control Law for a Vapor Compression Cycle System

2016 ◽  
Author(s):  
Anhtuan D. Ngo ◽  
Joshua R. Cory
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Thermal Load ◽  
Cooling System ◽  
Thermal System ◽  
Control Input ◽  
Vapor Compression ◽  
Error Performance ◽  
Vapor Compression Cycle ◽  
Compression Cycle

During the development of next generation tactical aircraft, thermal management is given significant consideration due to higher transient cooling demands, with stricter temperature limits along with the smaller size and weight in the cooling system hardware. Traditional control approaches, such as proportional-integral-derivative (PID), are sufficient to achieve the desired steady-state error performance for a thermal system with no constraints on the control inputs. The traditional control techniques may not be well-suited for thermal systems with constrained inputs. In this paper, we apply the Model Predictive Control (MPC) technique on an input-constrained thermal system and examine the system performance under a large transient thermal load and control input limits through the anticipation of the known thermal load. The results include design and implementation of an MPC controller for a high-fidelity, nonlinear vapor compression cycle model, as well as comparison of the MPC results to those of a finely tuned PID controller.

The Steady-State Modeling and Analysis of a Two-Loop Cooling System for High Heat Flux Removal

2009 ◽  
Author(s):  
Rongliang Zhou ◽  
Juan Catano ◽  
Tiejun Zhang ◽  
John T. Wen ◽  
Greg J. Michna ◽  
...  
Keyword(s):  
Heat Flux ◽  
Steady State ◽  
Heat Exchangers ◽  
Cooling System ◽  
High Heat ◽  
System Structure ◽  
High Heat Flux ◽  
Vapor Compression ◽  
Vapor Compression Cycle ◽  
Compression Cycle

Steady-state modeling and analysis of a two-loop cooling system for high heat flux removal applications are studied. The system structure proposed consists of a primary pumped loop and a vapor compression cycle (VCC) as the secondary loop to which the pumped loop rejects heat. The pumped loop consists of evaporator, condenser, pump, and bladder liquid accumulator. The pumped loop evaporator has direct contact with the heat generating device and CHF must be higher than the imposed heat fluxes to prevent device burnout. The bladder liquid accumulator adjusts the pumped loop pressure level and, hence, the subcooling of the refrigerant to avoid pump cavitation and to achieve high critical heat flux (CHF) in the pumped loop evaporator. The vapor compression cycle of the two-loop cooling system consists of evaporator, liquid accumulator, compressor, condenser and electronic expansion valve. It is coupled with the pumped loop through a fluid-to-fluid heat exchanger that serves as both the vapor compression cycle evaporator and the pumped loop condenser. The liquid accumulator of the vapor compression cycle regulates the cycle active refrigerant charge and provides saturated vapor to the compressor at steady state. The heat exchangers are modeled with the mass, momentum, and energy balance equations. Due to the projected incorporation of microchannels in the pumped loop to enhance the heat transfer in heat sinks, the momentum equation, rarely seen in previous refrigeration system modeling efforts, is included to capture the expected significant microchannel pressure drop witnessed in previous experimental investigations. Electronic expansion valve, compressor, pump, and liquid accumulators are modeled as static components due to their much faster dynamics compared with heat exchangers. The steady-state model can be used for static system design that includes determining the total refrigerant charge in the vapor compression cycle and the pumped loop to accommodate the varying heat load, sizing of various components, and parametric studies to optimize the operating conditions for a given heat load. The effect of pumped loop pressure level, heat exchangers geometries, pumped loop refrigerant selection, and placement of the pump (upstream or downstream of the evaporator) are studied. The two-loop cooling system structure shows both improved coefficient of performance (COP) and CHF overthe single loop vapor compression cycle investigated earlier by authors for high heat flux removal.

Rechargeable Personal Air Conditioning Device

2016 ◽  
Author(s):  
Yilin Du ◽  
Jan Muehlbauer ◽  
Jiazhen Ling ◽  
Vikrant Aute ◽  
Yunho Hwang ◽  
...  
Keyword(s):  
Air Conditioning ◽  
Cooling System ◽  
Cooling Capacity ◽  
Comfort Level ◽  
Vapor Compression ◽  
Air Conditioning System ◽  
System A ◽  
Single Person ◽  
Vapor Compression Cycle ◽  
Compression Cycle

A rechargeable personal air-conditioning (RPAC) device was developed to provide an improved thermal comfort level for individuals in inadequately cooled environments. This device is a battery powered air-conditioning system with the phase change material (PCM) for heat storage. The condenser heat is stored in the PCM during the cooling operation and is discharged while the battery is charged by using the vapor compression cycle as a thermosiphon loop. The conditioned air is discharged towards a single person through adjustable nozzle. The main focus of the current research was on the development of the cooling system. A 100 W cooling capacity prototype was designed, built, and tested. The cooling capacity of the vapor compression cycle measured was 165.6 W. The PCM was recharged in nearly 8 hours under thermosiphon mode. When this device is used in the controlled built environment, the thermostat setting can be increased so that building air conditioning energy can be saved by about 5–10%.

scholarly journals Dryout avoidance control for multi-evaporator vapor compression cycle cooling

2015 ◽  
Vol 160 ◽  
pp. 266-285 ◽  
Author(s):  
Daniel T. Pollock ◽  
Zehao Yang ◽  
John T. Wen
Keyword(s):  
Vapor Compression ◽  
Vapor Compression Cycle ◽  
Compression Cycle ◽  
Avoidance Control

Performance evaluation of a combined ejector-vapor compression cycle

2013 ◽  
Vol 55 ◽  
pp. 331-337 ◽  
Author(s):  
Jia Yan ◽  
Wenjian Cai ◽  
Lei Zhao ◽  
Yanzhong Li ◽  
Chen Lin
Keyword(s):  
Performance Evaluation ◽  
Vapor Compression ◽  
Vapor Compression Cycle ◽  
Compression Cycle

scholarly journals KAJI PERFORMANSI REFRIGERAN R-290, R-32, DAN R-410A SEBAGAI ALTERNATIF PENGGANTI R-22

2021 ◽  
Vol 4 ◽  
pp. 133-139
Author(s):  
Rikhard Ufie ◽  
Cendy S. Tupamahu ◽  
Sefnath J. E. Sarwuna ◽  
Jufraet Frans
Keyword(s):  
Air Conditioning ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Condensation Temperature ◽  
Vapor Compression ◽  
Know How ◽  
Evaporation Temperature ◽  
Vapor Compression Cycle ◽  
Compression Cycle ◽  
Refrigeration Capacity

Refrigerant R-22 is a substance that destroys the ozone layer, so that in the field of air conditioning it has begun to be replaced, among others with refrigerants R-32 and R-410a, and also R-290. Through this research, we want to know how much Coefficient of Performance (COP) and Refrigeration Capacity (Qe) can be produced for the four types of refrigerants. The study was carried out theoretically for the working conditions of the vapor compression cycle with an evaporation temperature (Tevap) of 0, -5, and -10oC, a further heated refrigerant temperature (ΔTSH) of 5 oC, a condensation temperature (Tkond) of 45 oC and a low-cold refrigerant temperature. (ΔTSC) 10 oC and compression power of 1 PK . The results of the study show that the Coefficient of Performance (COP) in the use of R-22 and R-290 is higher than the use of R-32 and R-410a, which are 4,920 respectively; 4,891; 4.690 and 4.409 when working at an evaporation temperature of 0 oC; 4.260; 4,234; 4.060 and 3.812 when working at an evaporation temperature of -5 oC; and amounted to 3,730; 3,685; 3,550 and 3,324 if working at an evaporation temperature of -10 oC. Based on the size of the COP, if this installation works with a compression power of 1 PK, then the cooling capacity of the R-22 and R-290 is higher than the R-32 and R-410a, which are 3,617 respectively. kW; 3,597 kW; 3,449 kW and 3,243 kW. If working at an evaporation temperature of 0 oC; 3.133 kW; 3.114 kW; 2,986 kW and 2,804 kW if working at an evaporation temperature of -5 oC; and 2,741 kW; 2,710 kW; 2,611 kW and 2,445 kW if working at an evaporation temperature of -10oC.

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