scholarly journals Energy and Exergy Analysis of an Absorption and Mechanical System for a Dehumidification Unit in a Gelatin Factory

Entropy ◽  
2021 ◽  
Vol 23 (4) ◽  
pp. 415
Author(s):  
Lucas Lima ◽  
Carlos Keutenedjian Mady
Keyword(s):  
Exergy Analysis ◽  
Binary Solution ◽  
Electrical Power ◽  
Lithium Bromide ◽  
Absolute Humidity ◽  
Working Fluid ◽  
Vapor Compression ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Environmental Air

In this paper, an energy and exergy analysis is applied to the air dehumidification unit of a liquid desiccant system in an industrial gelatin conveyor dryer. The working fluid is a binary solution of lithium chloride (LiCl) in water. Dry air is used in order to decrease the amount of liquid in the gelatin. Therefore, the environmental air must have its absolute humidity reduced from about 12 g/kg to the project target, which is 5 g/kg. The process is a cycle using an absorption desiccant unit (LiCl in water), where the weak solution absorbs water vapor from the air. In the regenerator, condensation of the solution (desorption) from the moist air occurs. As a result, the steam consumption of the desorber and electrical power used for the vapor compression chiller (with ammonia, NH3, as working fluid) are the primary sources of cost for the factory. To improve the plant’s energy and exergy behaviors, the process is evaluated using a mathematical model of the system processes. In addition, we evaluate the substitution of the vapor compression chiller by an absorption unit (lithium bromide (LiBr) in water). The performance indicators of the compression vapor systems showed the best results. Even when using the condenser’s energy to pre-heat the solution, the installed system proved to be more effective.

scholarly journals Energy and Exergy Analysis of Combined Organic Rankine Cycle-Single and Dual Evaporator Vapor Compression Refrigeration Cycle

2019 ◽  
Vol 9 (23) ◽  
pp. 5028 ◽  
Author(s):  
Pektezel ◽  
Acar
Keyword(s):  
Exergy Analysis ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Refrigeration Cycle ◽  
Vapor Compression ◽  
Exergy Destruction ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Vapor Compression Refrigeration

This paper presents energy and exergy analysis of two vapor compression refrigeration cycles powered by organic Rankine cycle. Refrigeration cycle of combined system was designed with single and dual evaporators. R134a, R1234ze(E), R227ea, and R600a fluids were used as working fluids in combined systems. Influences of different parameters such as evaporator, condenser, boiler temperatures, and turbine and compressor isentropic efficiencies on COPsys and ƞex,sys were analyzed. Second law efficiency, degree of thermodynamic perfection, exergy destruction rate, and exergy destruction ratio were detected for each component in systems. R600a was determined as the most efficient working fluid for proposed systems. Both COPsys and ƞex,sys of combined ORC-single evaporator VCR cycle was detected to be higher than the system with dual evaporator.

scholarly journals Heat Pump Cycle Efficiency for Heat Supply

2020 ◽  
pp. 136-142
Author(s):  
Mykola Bosiy ◽  
◽  
Olexandr Kuzyk ◽  
Keyword(s):  
Heat Pump ◽  
Heat Supply ◽  
Exergy Analysis ◽  
Conversion Factor ◽  
Working Fluid ◽  
Heating Systems ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Heat Supply Systems ◽  
Supply Systems

The aim of the article is to analyze the literature and scientific publications on the effectiveness of the heat pump in heat supply systems and to study the efficiency of using the steam compression cycle of a heat pump in a heat supply system. Тo conduct energy and exergy analysis of heat pump efficiency indicators, the working fluid of which is freon R134a, when using natural waters as a source of low-potential thermal energy. The article analyzes the literature sources and scientific publications on the effectiveness of the heat pump in heat supply systems. The results of research of efficiency of application of the heat pump in systems of heat supply at use of natural waters as a source of low-potential thermal energy are presented. Energy and exergy analysis of heat pump efficiency indicators, the working fluid of which is R134a freon, was performed. The energy efficiency of the heat pump cycle was determined by the conversion factor of the heat pump. The thermodynamic efficiency of the heat pump in heat supply systems was evaluated using exergetic efficiency, which is one of the main indicators of the efficiency of heat pump processes and cycles. The calculation of energy indicators of the heat pump, such as: specific heat load in the evaporator and condenser, as well as the conversion factor of the heat pump. The calculation of exergetic efficiency for ambient temperature from +10 to -10 ºC. Thus, the energy and exergy analysis of the efficiency of the heat pump, the working fluid of which is Freon R134a with a conversion factor = 4.8. This indicates that the heat pump is a reliable, highly efficient, environmentally friendly source of energy for use in heating systems. A heat pump heating system will always consume less primary energy than traditional heating systems if natural water is used as a low-temperature heat source for the heat pump. The efficiency of the steam compression cycle of the heat pump largely depends on the temperature of low-potential heat sources. The use of HV in heating systems reduces greenhouse gas emissions compared to conventional types of heat supply, which is relevant to the ecological state of the environment.

scholarly journals Energy and Exergy Analysis of LiBr-aq and LiCl-aq Liquid Desiccant Dehumidification System

2020 ◽  
Vol 14 (1) ◽  
pp. 36-40
Author(s):  
Barış KavasoğullarI ◽  
Ertuğrul Cihan ◽  
Hasan Demir
Keyword(s):  
Exergy Analysis ◽  
Lithium Bromide ◽  
Exergy Efficiency ◽  
Coefficient Of Performance ◽  
Airflow Rate ◽  
Liquid Desiccant ◽  
Energy And Exergy ◽  
Liquid Desiccant Dehumidification ◽  
Energy And Exergy Analysis ◽  
Mass Flow Rates

In this study, energy and exergy analysis of experimental results obtained from a dehumidification system using LiBr-aq (lithium bromide-water) and LiCl-aq (lithium chloridewater) as desiccant was made. In dehumidifier and regenerator columns polycarbonate sheets, which have not been used before, were used as packing material to increase contact area in purposed liquid desiccant dehumidification system. In the analysis, variation of electrical coefficient of performance and exergy efficiency with airflow rate for different solution mass flow rates were investigated. Because of investigation, maximum values of electrical coefficient of performance and exergy efficiency were calculated approximately as 2.8 and 18%, respectively.

scholarly journals Energy and Exergy Analysis of the Air Source Transcritical CO2 Heat Pump Water Heater Using CO2-Based Mixture as Working Fluid

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4470
Author(s):  
Yikai Wang ◽  
Yifan He ◽  
Yulong Song ◽  
Xiang Yin ◽  
Feng Cao ◽  
...  
Keyword(s):  
Exergy Analysis ◽  
Heat Pumps ◽  
Exergy Efficiency ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Domestic Hot Water ◽  
Practical Applications ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis

Given the large demand nowadays for domestic hot water, and its impact on modern building energy consumption, air source transcritical CO2 heat pumps have been extensively adopted for hot water production. Since their system efficiency is limited by significant irreversibility, a CO2-based mixture could offer a promising drop-in technology to overcome this deficiency without increasing system complexity. Although many CO2 blends have been studied in previously published literature, little has been presented about the CO2/R32 mixture. Therefore, a proposed mixture for use in transcritical CO2 heat pumps was analyzed using energy and exergy analysis. Results showed that the coefficient of performance and exergy efficiency variation displayed an “M” shape trend, and the optimal CO2/R32 mixture concentration was determined as 0.9/0.1 with regard to flammability and efficiency. The irreversibility of the throttling valve was reduced from 0.031 to 0.009 kW⋅kW−1 and the total irreversibility reduction was more notable with ambient temperature variation. A case study was also conducted to examine domestic hot water demand during the year. Pure CO2 and the proposed CO2 blend were compared with regard to annual performance factor and annual exergy efficiency, and the findings could provide guidance for practical applications in the future.

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