scholarly journals Energy and exergy estimation for a combined cycle of solid CO2 production and NH3-H2O single effect absorption chiller

2016 ◽  
Vol 19 (1) ◽  
pp. 61-69 ◽  
Author(s):  
Phu Minh Nguyen
Keyword(s):  
Cooling System ◽  
Cooling Water ◽  
Combined Cycle ◽  
Co2 Production ◽  
Absorption Chiller ◽  
Cooling Water Temperature ◽  
Cycle Simulation ◽  
Energy And Exergy ◽  
Single Effect ◽  
Exergy Analyses

In order to reduce the compression power, to use an integrated thermal-driven cycle, and to mitigate the CO2 content in the air, a new combined cycle of absorption chiller and vaporcompression refrigeration cycle to produce carbon dioxide dry ice was devised and analyzed. In this study, the energy and the exergy analyses of the combined cycle were presented. The combined cycle simulation was carried out by using EES (Engineering Equation Solver) program. The CO2 condensation pressure and the generator temperature were considered as key parameters. Results show that the total compression and pumping power using the present combined cycle can be reduced remarkably, amounting to 44.4 %, in comparison with that in the conventional ammonia cooling system. Most of the irreversibility occur in the absorption system and the irreversibility of the absorber has the largest portion. The temperature reduction of the solution or increase in the cooling water temperature can improve the irreversibility of the absorber. However, the latter decreases the irreversibility more than the former.

Gas Turbine Performance Enhancement by Inlet Air Cooling and Coolant Pre-Cooling Using an Absorption Chiller

2016 ◽  
Author(s):  
Hyun Min Kwon ◽  
Jeong Ho Kim ◽  
Tong Seop Kim
Keyword(s):  
Gas Turbine ◽  
Air Temperature ◽  
Power Plants ◽  
Cooling System ◽  
Combined Cycle ◽  
Air Cooling ◽  
Absorption Chiller ◽  
Large Power ◽  
Cycle Simulation ◽  
Standard Design

The gas turbine combined cycle is the most mature and efficient power generation system. While enhancing design performance continuously, a parallel effort to make up for the shortcomings of the gas turbine should be pursued. The most critical drawback is the large power loss in hot season when electricity demand is usually the highest. Therefore, it is important to implement an effective power boosting measure in gas turbine based power plants, especially in areas where the annual average temperature is much higher than the standard design ambient temperature. The simplest method in general is to reduce the gas turbine inlet air temperature by any means. Several schemes are commercially available, such as mechanical chilling, evaporative cooling, inlet fogging and absorption chilling. All of them have merits and demerits, either thermodynamically and economically. In this study, we focused our interest on the absorption chilling method. Theoretically, absorption chilling provides as much cooling effect (air temperature reduction) as the mechanical chilling, while electric power consumption is negligibly small. A distinct feature of an absorption chiller in contrast to a mechanical chiller is that thermal energy (heat) is needed to drive the chilling system. In this research, we propose an innovative idea of making the independent heat supply unnecessary. The new method provides simultaneous cooling of the turbine coolant and the inlet air using an absorption chiller. The inlet cooling and coolant precooling boost the gas turbine power synergistically. We predicted the system performance using cycle simulation and compared it with that of the conventional mechanical cooling system.

scholarly journals Analysis of a New Dissipation System for a Solar Cooling Installation

2010 ◽  
Vol 2010 ◽  
pp. 1-6
Author(s):  
Carlos Monné Bailo ◽  
Sergio Alonso Garcés ◽  
Fernando Palacín Arizón
Keyword(s):  
Water Temperature ◽  
Cooling System ◽  
Cooling Water ◽  
Absorption Chiller ◽  
Geothermal Heat ◽  
Solar Absorption ◽  
Cooling Water Temperature ◽  
Solar Cooling ◽  
Flat Plate Collector ◽  
The University

This paper describes a solar absorption cooling installation located at the University of Zaragoza (Spain). The installation is based on the performance of an absorption chiller. The solar cooling system consists of 37,5 m2 of flat plate collector, a 4.5 kW, single-effect LiBr-H2O absorption chiller, and a dry cooling tower. The installation provides cooling to a gymnasium belonging to the sports center of the university. To carry out the installation analysis, the system was continuously monitored. In 2007, 2008 and 2009, several studies have been performed in order to analyze the full system operation. The measured data showed the strong influence of the cooling water temperature and the generator driving temperature on the COP. Due to the experimental evidence of the influence of the cooling water temperature, a new heat rejection system based on a geothermal heat sink has been installed and studied.

Simulation and Experimental Analysis of a Solar Driven Absorption Chiller With Partially Wetted Evaporator

2008 ◽  
Author(s):  
Jan Albers ◽  
Giovanni Nurzia ◽  
Felix Ziegler
Keyword(s):  
Cooling System ◽  
Cooling Water ◽  
Hot Water ◽  
Absorption Chiller ◽  
Efficient Operation ◽  
Part Load ◽  
Solar Cooling ◽  
Wetted Area ◽  
Solar Cooling System ◽  
Load Conditions

The efficient operation of a solar cooling system strongly depends on the chiller behaviour under part-load conditions since driving energy and cooling load are never constant. For this reason the performance of a single stage, hot water driven 30 kW H2O/LiBr-absorption chiller employed in a solar cooling system with a field of 350 m2 evacuated tube collectors has been analysed under part-load conditions with both simulations and experiments. A simulation model has been developed for the whole absorption chiller (Type Yazaki WFC-10), where all internal mass and energy balances are solved. The connection to the external heat reservoirs of hot, chilled and cooling water is done by lumped and distributed UA-values for the main heat exchangers. In addition to an analytical evaporator model — which is described in detail — experimental correlations for UA-values have been used for condenser, generator and solution heat exchanger. For the absorber a basic model based on Nusselt theory has been employed. The evaporator model was developed taking into account the distribution of refrigerant on the tube bundle as well as the change in operation from a partially dry to an overflowing evaporator. A linear model is derived to calculate the wetted area. The influence of these effects on cooling capacity and COP is calculated for three different combinations of hot and cooling water temperature. The comparison to experimental data shows a good agreement in the various operational modes of the evaporator. The model is able to predict the transition from partially dry to an overflowing evaporator quite well. The present deviations in the domain with high refrigerant overflow can be attributed to the simple absorber model and the linear wetted area model. Nevertheless the results of this investigation can be used to improve control strategies for new and existing solar cooling systems.

scholarly journals The Impact of Coolant Temperatures on Various Cycle Parameters of NH3-H2O Absorption Chiller from Solar Source

2021 ◽  
pp. 43-50
Author(s):  
Adel Akair ◽  
Hesham Baej
Keyword(s):  
Water Temperature ◽  
Temperature Increase ◽  
Cooling Water ◽  
Relative Difference ◽  
Inlet Temperature ◽  
Absorption Chiller ◽  
Ammonia Water ◽  
Solar Source ◽  
Cooling Water Temperature ◽  
The Difference

The cycles’ structure was based on recently published technical information of low-temperatures powered Ammonia-water (NH3-H2O) absorption chiller.  The cycle was completely modeled using different components available within the refrigeration library of IPSEpro software package.  Using the model a cold-water ammonia-water absorption chiller was examined and validated in accordance to the relevant thermodynamic laws and charts. A low-grade temperature solar resource was modeled to energise the proposed model. For water-cooled cycles, the rejected heat from the absorbers and the condensers was carried out by water, at an average fixed temperature of 25°C, pumped out from ground water. The results obtained show that when the Coefficient of performance (COP), heat inputs into the generator, and cooling mass flow rates are fixed, the cycle parameters are highly affected by variation of coolant temperature. For instance when cooling water temperature decreases. Also when cooling water temperature increase, the cycle pressure, usable chilled water temperature difference and desorber outlet temperature increase whereas mass concentration and refrigeration capacity decrease. The effectiveness of the generator inlet temperature (solar source) is a factor of the largest effect to the COP. The difference was 0.1401, 27.4%. The chilled water inlet temperature (underground water) is the second largest effect to the COP. The difference between the maximum and the minimum value is 0.0865 and the relative difference is 18.9% with cooling capacity 12 kW. The influence of evaporator temperature to the COP is also minimal with only 2.2% difference. The influence of absorber temperature and condenser temperature to the COP are almost identical, the relative difference is 19.2% and 18.9% respectively.

Research and Application of the Auto-Control Cooling System for the Diesel Engine

2013 ◽  
Vol 805-806 ◽  
pp. 1970-1974
Author(s):  
Hong Lei Pang ◽  
Cai Yun Zhu ◽  
Zhi Bin Ni ◽  
Yao Hua Wei
Keyword(s):  
Diesel Engine ◽  
Water Temperature ◽  
Cooling System ◽  
Cooling Water ◽  
Coolant Temperature ◽  
Saving Rate ◽  
Fuel Saving ◽  
Single Chip ◽  
Cooling Water Temperature ◽  
Operation Conditions

In order to solve the problem that the traditional cooling system cannot adjust the cooling water temperature to the different operation conditions of diesel engine, the auto-control cooling system is designed. Using it, the coolant temperature can be adjusted automatically by the single-chip which controls the transducer-controlled pump and the electronic dividing valve which replaces the thermostat. We use the thermal equilibrium bench to verify the figures, and the result is show that using the exhaust of generator heats the cooling water can shorten 13 minutes in starting process and the cooling water temperature adjusted automatically to the changing operation conditions of iesel can decrease the fuel consumption remarkably, the highest fuel saving rate reached 5.4%, the averagely fuel saving rate reached 3.6%.

scholarly journals Thermodynamic Analysis of a Solar Combined Ejector Absorption Cooling System

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Doniazed Sioud ◽  
Raoudha Garma ◽  
Ahmed Bellagi
Keyword(s):  
Cooling System ◽  
Lithium Bromide ◽  
Cooling Water ◽  
Double Effect ◽  
Cycle Performance ◽  
Working Fluid ◽  
Absorption Cooling ◽  
Single Effect ◽  
Absorption Cycle ◽  
Absorption Cooling System

The objective of this paper is to investigate theoretically a solar driven 60 kW absorption cooling system. The system is constituted of a combined ejector single-effect absorption cycle coupled with a linear Fresnel solar concentrator and using water/lithium bromide as working fluid. The combined ejector single-effect absorption cycle exhibits high performances, almost equal to that of double-effect absorption device. However, higher driving heat temperatures are required than in the case of conventional single-effect machines. A mathematical model is set up to analyze the optical performance of the linear Fresnel concentrator. Simulations are carried out to study the overall system performance COPsystem and the performances of the combined absorption machine COPcycle for generator driving temperatures and pressures in the ranges 180°C – 210°C and 198 kPa – 270 kPa, respectively. Further, the effect of operating parameters such as the cooling medium and chilled water temperatures is investigated. A maximum cycle performance of 1.03 is found for a generator pressure of 272 kPa and chilled and cooling water temperatures of 7°C and 25°C, respectively. A case study is investigated for a typical summer Tunisian day, from 8:00 to 18:00. The effect of ambient temperature and solar radiation on cycle and system performances is simulated. The optical performances of the concentrator are also analyzed. Simulation results show that between 11:00 and 14:00 the collector efficiency is 0.61 and that the COPcycle reaches values always higher than 0.9 and the COPsystem is larger than 0.55. Globally the performances of the investigated cycle are similar to those of double-effect conventional absorption system.

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