INFLUENCE OF THE SOLUTION HEAT EXCHANGER EFFICIENCY ON THE PERFORMANCE OF A SINGLE EFFECT H2O-LiBr ADIABATIC ABSORPTION SYSTEM

2011 ◽  
Vol 19 (02) ◽  
pp. 107-112 ◽  
Author(s):  
GEYDY GUTIÉRREZ URUETA ◽  
PEDRO RODRÍGUEZ AUMENTE ◽  
MARIA RODRÍGUEZ HIDALGO ◽  
ANTONIO LECUONA NEUMANN
Keyword(s):  
Heat Exchanger ◽  
Strong Solution ◽  
Heat Transfer Process ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Test Facility ◽  
Absorption System ◽  
Experimental Conditions ◽  
Single Effect ◽  
Absorption Cycle

This work analyzes the effect that particular operating conditions of a single effect H2O - LiBr adiabatic absorption system have on a plate-type solution heat exchanger efficiency. The corresponding influence of such efficiency on the performance of facility under study is evaluated. As a result of the design of experimental test facility, the functioning of the strong solution circuit leads to take into account some particular operating conditions which affect the correct performance of the solution heat exchanger. For some experimental conditions, the strong solution side is not completely filled by the solution fluid. As a consequence of this, the heat transfer process is affected, reducing the solution heat exchanger efficiency and changing greatly the resulting coefficient of performance (COP) of the absorption facility. In order to illustrate this phenomenon, this paper offers graphical results including: solution working temperatures, solution heat exchanger efficiency and COP in a time sequence of an experiment, as well as for fixed steady-state operating conditions. These results show the importance of a correct functioning of the solution heat exchanger on the performance of an absorption system. The results are useful for researchers interested in new absorption cycle designs.

Performance Analyses of Photovoltaic Thermal Integrated Concentrator Collector Combined With Single Effect Absorption Cooling Cycle: Constant Flow Rate Mode

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Md. Meraj ◽  
M.E. Khan ◽  
Md. Azhar
Keyword(s):  
Climatic Conditions ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Design Parameters ◽  
Inlet Temperature ◽  
New Delhi ◽  
Absorption System ◽  
Simulation Code ◽  
Single Effect ◽  
Performance Analyses

Abstract In the present communication, performance analyses of interconnected N number of fully covered semitransparent photovoltaic thermal integrated concentrator collectors combined with single effect vapor absorption refrigeration system have been carried out. The proposed system was analyzed under the constant mass flowrate of collectors’ fluid. Mathematical expressions have also been derived for generator temperature of the absorption unit as a function of both design and operating parameters. Further, simulations have been performed for a typical day of May month of New Delhi climatic conditions. Performance parameters have been evaluated such as collector exit temperature, generator inlet temperature, electrical power output, electrical efficiency, overall thermal energy gain, instantaneous thermal efficiency, overall exergy gain and coefficient of performance of the absorption system. The simulation code has been written in matlab. From the present analyses, the following salient conclusions have been drawn: Operating generator temperature of the absorption system is suitable for five number of photovoltaic thermal-integrated parabolic concentrator collector connected in series. The proposed system will continue operating for 5 h during May month in New Delhi climate conditions. The maximum solar coefficient of performance, refrigeration coefficient of performance, and exergy coefficient of performance are reported as 0.1551, 0.8344, and 0.2697, respectively, for the proposed novel system under given design and operating conditions. Additionally, the effects of other design parameters of this novel system have also been investigated.

scholarly journals Design Analysis and Fabrication of Solar Vapour Absorption

2019 ◽  
Vol 8 (9S3) ◽  
pp. 371-376 ◽  
Keyword(s):  
Heat Exchanger ◽  
Heat Energy ◽  
Solar Irradiation ◽  
Absorption System ◽  
Evaporator Temperature ◽  
Fluid Systems ◽  
Parabolic Dish ◽  
Photo Voltaic ◽  
Absorption Cycle ◽  
Hourly Basis

Solar energy is one of the greenest sources of electricity and the idea of using it to power transportation is not new. In this work, parabolic dish is used to collect the solar irradiation, instead of Photo voltaic cells (PVC). This radiation is focused on to a point, where the water is heated to the required temperature and this heat energy is transferred to vapour absorption unit through the heat exchanger. In vapour absorption system (Three fluid systems) consists of a combination of three fluids ammonia and water and hydrogen. These fluids complete the vapour absorption cycle and provide the sufficient cooling. The experiments are conducted on the Solar Vapour absorption unit from 9:00A.M to 5:00P.M. For two days. Temperature readings of generator, Evaporator are taken on an hourly basis and C.O.P of the system at the minimum evaporator temperature is calculated. The system had attained a minimum evaporator temperature of 23⁰C at its peak generator temperature of 92⁰C.

Theoretical Analysis and Experimental Researches on Internal Heat Exchanger in CO2 Trans-Critical Cycle

2012 ◽  
Vol 204-208 ◽  
pp. 4336-4342
Author(s):  
Hui Xia Lu ◽  
Jing Lv ◽  
Zhe Bin He ◽  
Jin Yu Wang ◽  
Jia Wei Zhou
Keyword(s):  
Heat Exchanger ◽  
Internal Heat ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Outlet Temperature ◽  
Internal Heat Exchanger ◽  
High Side ◽  
Side Pressure ◽  
Experimental Researches ◽  
Regenerative Cycle

The change of system performance caused by regenerative cycle in different operating conditions was analyzed in this paper, comparing the cycle with or without internal heat exchanger in a CO2 trans-critical cycle. We analyzed theoretically the performance of CO2 trans-critical cycle with the internal heat exchanger, and found that the coefficient increased with the decreasing of the high side pressure and the increasing of outlet temperature in gas cooler, in a certain range of the high side pressure and outlet temperature. The evaporation temperature could be raised when the system with internal heat exchanger and at the same time the coefficient of performance could be improved obviously. At lower high side pressure, the performance coefficient could be improved significantly by increasing the suction superheat. The higher the gas cooler outlet temperature was, the more obvious the increase was.

scholarly journals Comparative Study of a Compression–Absorption Cascade System Operating with NH3-LiNO3, NH3-NaSCN, NH3-H2O, and R134a as Working Fluids

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 816
Author(s):  
JV Herrera-Romero ◽  
Dario Colorado-Garrido
Keyword(s):  
Heat Exchanger ◽  
Heat Source ◽  
Coefficient Of Performance ◽  
Condensation Temperature ◽  
Cascade System ◽  
Working Fluids ◽  
Temperature Range ◽  
Source Temperature ◽  
Compression Cycle ◽  
Absorption Cycle

This research presents a comprehensive bibliographic review from 2006 through 2020 about the state of the art of the compression–absorption cascade systems for refrigeration. In consequence of this review, this research identifies the significant development of systems that consider lithium bromide as a working fluid; however, the use of other working fluids has not been developed. This study is motivated toward the development of a parametric analysis of the cascade system using NH3-LiNO3, NH3-NaSCN and NH3-H2O in the absorption cycle and R134a in the compression cycle. In this study, the effect of the heat source temperature, condensation temperature in the compression cycle, the use of heat exchangers in the system (also known as economizers) and their contribution to the coefficient of performance is deepened numerically. The economizers evaluated are the following: an internal heat exchanger, a refrigerant heat exchanger, a solution refrigerant heat exchanger, and a solution heat exchanger. Mass and energy balance equations—appropriate equations to estimate the thermophysical properties of several refrigerant–absorbent pairs—were used to develop a thermodynamic model. The studied heat source temperature range was from 355 to 380 K, and the studied condensation temperature range in the compression cycle was from 281 to –291 K; additionally, the importance of each economizer on the coefficient of performance was numerically estimated. In this way, NH3-NaSCN solution in the absorption cycle and R134a in the compression cycle provided promising numerical results with the highest COPs (coefficient of performance).

Performance characteristics of natural-refrigerants- based ejector expansion refrigeration cycles

2009 ◽  
Vol 223 (5) ◽  
pp. 543-550 ◽  
Author(s):  
J Sarkar
Keyword(s):  
Heat Exchanger ◽  
Internal Heat ◽  
Area Ratio ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Internal Heat Exchanger ◽  
Optimum Parameters ◽  
And Performance ◽  
Vapour Compression ◽  
Cycle Temperature

The thermodynamic analyses and comparison of three natural-refrigerants-based vapour compression refrigeration cycles (ammonia, isobutane, and propane) are presented in this article using a constant pressure mixing ejector as an expansion device. Optimization of the area ratio of the ejector is done based on maximum cooling coefficient of performance (COP) and performance improvement for different operating conditions. The effect of using an internal heat exchanger is studied as well. Results show that optimum area ratio and cooling COP increases with a decrease in cycle temperature lift, whereas the COP improvement over basic expansion cycle increases with the increase in cycle temperature lift. Study shows that the optimum parameters, as well as performance using the ejector as an expansion device, are strongly dependent on the refrigerant properties as well as the operating conditions. The optimum area ratio is maximum for ammonia and minimum for propane, whereas maximum cooling COPs are similar. Using the ejector as an expansion device, propane yields a maximum COP improvement of 26.1 per cent followed by isobutane (22.8 per cent) and ammonia (11.7 per cent) for studies ranges. The effect of using an internal heat exchanger in the ejector expansion refrigeration cycle is found to be not profitable.

Measured Performance and Modeling of an Evacuated-Tube, Integral-Collector-Storage Solar Water Heater

1995 ◽  
Vol 117 (3) ◽  
pp. 221-228 ◽  
Author(s):  
A. A. Mason ◽  
J. H. Davidson
Keyword(s):  
Energy Gain ◽  
Operating Conditions ◽  
Test Facility ◽  
Test Duration ◽  
Water Heater ◽  
Solar Simulator ◽  
Experimental Conditions ◽  
Optical Efficiency ◽  
Radiation Induced ◽  
Evacuated Tube

An experimental study of an evacuated-tube, integral-collector-storage water heater was conducted in an indoor solar simulator. Useful collected energy, radiation-induced stratification and draw-induced mixing are characterized in eight trials in which test duration, initial tank water temperature, flow rate during withdrawal of heated water from the collector, withdrawal pattern and reflectance of the back-plane were varied. All tests were performed at nominal irradiance of 900 W/m2, normal incidence, and collector slope of 45 degrees. The capability of the TRNSYS integral collector storage model to predict performance for operating conditions for which data are assumed to be unavailable was assessed. Using data from one experimental trial, optical efficiency (τα) of the collector was determined by matching predicted useful energy gain to measured gain. Effectiveness of the calibrated model was based on a comparison of predicted gains to measured values obtained in the remaining seven trials. For five of seven trials, predicted performance is within nine percent of measured performance and less than experimental error. For the other two trials, predicted performance is within 15 percent of measured performance. The higher discrepancies may be partially due to experimental conditions not modeled such as heating of the piping connecting the collector to the test facility and inadequate characterization of back-plane reflectivity. The model does not predict radiation-induced stratification. Although the effect of mixing during draws can be approximated by specifying the number of fully mixed volume segments in the tanks, selection of number of nodes requires knowledge of the behavior of the system. The number of nodes selected has minimal impact on total energy gain, but does affect the temperature of water delivered to the load.

EVALUATION OF A COMBINED SOLAR-ASSISTED EJECTOR ABSORPTION CHILLER

2013 ◽  
Vol 42 (1) ◽  
pp. 56-60
Author(s):  
Kamaruzzaman Sopian ◽  
J. Abdulateef ◽  
M. Alghoul ◽  
K.S. Yigit
Keyword(s):  
Experimental Investigation ◽  
Heat Exchanger ◽  
Solar Energy ◽  
Operating Conditions ◽  
Working Fluid ◽  
Absorption System ◽  
Absorption Chiller ◽  
Maximum Increase ◽  
Evacuated Tube

The experimental investigation of the performance of a combined solar ejector absorption coolingsystem has been carried out. The system was installed in the solar energy park at University KebangsaanMalaysia. The influence of various operating conditions on the COP is studied using evacuated tube solarcollectors and NH3-H2O as working fluid. The results showed that, the absorption chiller provides high COPthan that of the conventional absorption system. The maximum COP of the cycle in the order of 0.6 when theimprovements of rectifier and solution heat exchanger are added while the maximum increase in COP in case ofcombined cycle is about 50% higher than the basic cycle. This study is provided an actual compact unit of 1.5cooling capacity and operated under real outside conditions for Malaysia and similar tropical regions.DOI: http://dx.doi.org/10.3329/jme.v42i1.15978

scholarly journals Performance evaluation of a novel PVT-GSHP heating system on energy-efficient poultry houses: long-term monitoring

2020 ◽  
Author(s):  
Tugba Gurler ◽  
Theo Elmer ◽  
Yuanlong Cui ◽  
Siddig Omer ◽  
Saffa Riffat
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Heating System ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Solar Pv ◽  
Pump System ◽  
Poultry House ◽  
Poultry Houses

Abstract The case study presented in this paper is an innovative ground source heat pump (GSHP) system constituted by a hybrid Photovoltaic Thermal (PVT) solar system for poultry houses. Farmers tend to not to apply GSHPs because of the high prices of excavation and time consumption. The innovative heat pump system assessed in this study comprises of a new type of heat exchangers; a thin-tube solar polyethylene heat exchanger installed between roof tiles and PV panels and a novel vertical ground heat exchanger to utilize the heat stored in the soil. The heating system applied to a poultry house are monitored and evaluated under a variety of environmental and operating conditions to achieve annual/long-term efficiency of the heating system in Kirton, UK. The maximum heating demand of the poultry house is determined 34.4 MWh/PC while the minimum is 11,1 MWh/PC. The monitored results show that the heat pump produced 15.02 MWh of thermal energy per annum. Solar PV and heat pump worked very well together with solar PV covering all the heat pump’s annual electrical energy requirement and generated 8.74 MWh of extra electricity exported to the grid. The seasonal coefficient of performance is found 3.73 through a year. The novel PVT-GSHP heating system is a very promising solution for high fossil fuel consumption in the agriculture industry and the energy savings of the whole system can be noticeably increased dependent up on the system controlling.

Experimental Measurements of an Air Conditioner Performance

2002 ◽  
Author(s):  
Luis Rosario ◽  
Muhammad M. Rahman ◽  
Jose L. F. Porteiro
Keyword(s):  
Experimental Data ◽  
Air Conditioning ◽  
Experimental Studies ◽  
Operating Conditions ◽  
System Capacity ◽  
Coefficient Of Performance ◽  
Test Facility ◽  
Experimental Program ◽  
Air Conditioner ◽  
Test Unit

The performance of the air conditioner was tested in an extensive experimental program using the environmentally controlled chambers in a test facility. Two psychometric rooms provided constant ambient temperature and humidity conditions for a test unit using ASHRAE standard procedures [1]. The indoor and outdoor units were placed into separate environmental chambers, which provided precise temperature, humidity, and airflow conditions for simulation of various operating conditions. The first goal of the experimental program was to define the range of conditions over which the test unit should be tested. The second goal of the experimental studies was to determine the performance of the test unit under the defined conditions. All air conditioner performance data has been collected with air side instrumentation only. Experimental tests were performed using the test unit over a range of outdoor temperatures between 22.4°C (80°F) and 40.6°C (105°F) and indoor temperatures between 18.3°C (65°F) and 35°C (95°F). Analysis of the experimental data was performed by studying air conditioning parameters such as heat rejection rate qc, compressor power W, system capacity qe, and coefficient of performance COP. The analysis was accomplished with the variation of a boundary condition. The sensitivity analysis of experimental data gave expected results when compared to those shown by air conditioning units similar to our test unit.

A theoretical and experimental study of a novel recompression absorption refrigeration cycle

2001 ◽  
Vol 215 (1) ◽  
pp. 75-87 ◽  
Author(s):  
I. W. Eames ◽  
S Wu
Keyword(s):  
Experimental Study ◽  
Theoretical Study ◽  
Lithium Bromide ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Absorption Refrigeration ◽  
Corrosion Rates ◽  
Steam Ejector ◽  
Single Effect ◽  
Absorption Cycle

This paper describes a novel vapour absorption refrigeration cycle which uses a steam ejector to enhance the concentration process of the cycle. The paper provides a complete description of the cycle and presents the results of a theoretical study before going on to describe and evaluate the outcomes of an experimental programme. The results of this investigation showed that with the addition of a steam ejector as described the coefficient of performance (COP) of the single-effect lithium bromide absorption cycle can be increased from about 0.7 to at least 1.0 without any increase in corrosion rates often associated with high temperature vapour generators used in conventional machines of this type.

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