• Issue 1 (2010)
• Issue 2 (2010)

Performances Assessment of Natural Refrigerants as Substitutes to CFC and HCFC in Hot Climate

IJTEE, volume-01 , Issue 2 (2010), PP 125 - 130

Published: 26 Jan 2010

DOI: 10.5383/ijtee.01.02.008

by M. Boumaza from Department of Chemical Engineering, College of Engineering, King Saud University, Saudi Arabia

Abstract: Due to the environmental concerns ozone depletion potential (ODP) and global warming potential (GWP) of the existing refrigerants, industry and researchers in this field are investigating long-term solutions. With extensive work on alternatives to chlorofluorocarbons (CFCs) and hydro chlorofluorocarbons (HCFCs), initially hydro fluorocarbons were considered to be long-term solutions. The global warming of HFCs has become a hurdle to accept them as long-term solutions. Now, the focus is on the use of natural refrigerants like hydrocarbons (HCs) such R290, R600, ammonia, carbon dioxide and water. These natural substances have very low GWP, and a zero ODP. This paper presents simulation results through a thermodynamic analysis of R22 and three of its alternatives natural refrigerants (R290, R600a and R717) for A/C and refrigeration purposes operating under various outdoor temperatures, represented by the condenser temperatures. The examined new refrigerants show varying performance, depending on the evaporator temperatures, but in every case, the condenser temperature seems to have an important impact on the performance of the cycle. read more... read less...

Keywords: refrigerants, substitutes, environment, ozone, performances.

Potential for Wind-Powered Desalination Systems in Jordan

IJTEE, volume-01 , Issue 2 (2010), PP 109 - 123

Published: 26 Jan 2010

DOI: 10.5383/ijtee.01.02.007

by Mousa S. Mohsen from Department of Mechanical Engineering, Hashemite University, Zarqa 13115, Jordan

Abstract: Desalination systems driven by renewable energies are limited, and they usually have a limited capacity. They only represent about 0.02% of total desalination capacity. However, many reasons make the use of renewable energies suitable for brackish and seawater desalination. In addition to shortage of fresh water resources, Jordan is suffering from shortages in recoverable commercial energy sources such as crude oil and natural gas. The limited energy sources in Jordan makes considering renewable energy options such as wind power very attractive, especially for remote areas. This will be extremely important for small-scale applications. Due to prevailing tough conditions, such as low water quality and shortage in supplies, there is a large demand for small desalination units, not only in locations not connected to a water supply network, but also as units for additional or independent supply. The coupling of wind energy and desalination systems holds great promise for increasing water supplies in water scarce regions. An effective integration of these technologies will allow countries to address water shortage problems with a domestic energy source that does not produce air pollution or contribute to the global problem of climate change. Meanwhile the costs of desalination and renewable energy systems are steadily decreasing, while fuel prices are rising and fuel supplies are decreasing. This paper specifically seeks to address the enhancement of the overall quantity of freshwater available in Jordan, by exploring the potential for integrating wind power and desalination technologies to increase water supplies. Both desalination and wind technologies are summarized in this paper, including growth trends, costs, and emerging technological advancements. These descriptions provide snapshots of the current status of these technologies and their markets, as both independent and integrated technologies. Meteorological data is then used to generate a map of Jordan wind-powered desalination potential “hotspots”, to give a rough idea where the integration of these technologies might be the most applicable. read more... read less...

Keywords: Wind-Powered Desalination, RO Desalination, Renewable Energy, Jordan

Water-Surrogate Fuel Emulsion Combustion Effect on CO and NOX Emissions

IJTEE, volume-01 , Issue 2 (2010), PP 99 - 108

Published: 26 Jan 2010

DOI: 10.5383/ijtee.01.02.006

by Abdulaziz H. El-Sinawi from College of Engineering, King Faisal University, Al-Ahsa, 31982, Saudi Arabia

Abstract: Water emulsified fuel is one of the few promising emission reduction techniques with the potential to reduce NOX in diesel engines. little effort has been directed towards modelling the combustion of water-in-fuel emulsion. This work provides a better understanding of the effects of the existence of water in fuel in the form of emulsion on spray combustion and pollutant emissions namely NOX and carbon monoxide by modelling the relevant processes and focusing on the variables behind the emission reduction criteria and performance. The commercially available software CHEMKIN IV was used to simulate spray combustion at diesel engine-relevant conditions. Surrogate fuel (80 % heptane and 20 % toluene) was used due to the available detailed kinetic and thermodynamic data needed for modelling. An emulsified fuel with 3, 5, 8 and 20 % water by volume is used as an engine feed for each run separately and the results are compared with that of the dry surrogate fuel of 0 % water. The modelling results show that water has a significant effect on reducing engine operating temperature, and NOX formation. However, the reduction of NOX is at the expense of an increase in carbon monoxide (CO) emissions and elongated ignition delay time, which is disadvantageous for the steady running diesel engines. read more... read less...

Keywords: water-surrogate fuel emulsion, combustion, CO and NOx emissions

Investigation on the Effect of Operating Parameters on the Performance of Solar Desiccant Cooling System Using Artificial Neural Networks

IJTEE, volume-01 , Issue 2 (2010), PP 91 - 98

Published: 26 Jan 2010

DOI: 10.5383/ijtee.01.02.005

by El-Shafei B. Zeidan, Ayman A. Aly, Ahmed M. Hamed from Department of Mechanical engineering, Faculty of Engineering, Taif University, Al-Hawyah, PO Box 888, Saudi Arabia

Abstract: A multiple-layer artificial neural network (ANN) model has been applied to study the performance of a solar liquid desiccant dehumidification/regeneration system. The experimental results of a previous study are used to construct and test the ANN model. Then the model has been utilized to describe the effect of the inlet conditions of the air and calcium chloride (CaCl2) solution on the regeneration process. Good agreement between the outputs from the ANN model and the corresponding results from the experimental data has been found. The proposed model can work well as a predictive tool to complement the experiments. read more... read less...

Keywords: Solar energy, dehumidification/regeneration, absorption, liquid desiccant, ANN, back propagation algorithm

Solar Assisted Gasification: Systematic Analysis and Numerical Simulation

IJTEE, volume-01 , Issue 2 (2010), PP 81 - 90

Published: 26 Jan 2010

DOI: 10.5383/ijtee.01.02.004

by Isam Janajreh, Shabbar Syed, Rana Qudaih, Ilham Talab from Masdar Institute of Science and Technology, Abu Dhabi, United Arab Emirates, P.O. Box 54224

Abstract: Hybrid solar thermo-chemical conversion process is a viable route to produce clean fuel using any carbonaceous material as feedstock and solar radiation to provide energy for endothermic reactions. The steam gasification of carbonaceous material under high energy solar flux provides a thermo-chemical pathway to produce syngas fuel i.e., hydrogen (H2) and carbon monoxide (CO). Therefore, in this study a steady state model of entrained flow gasifier is simulated utilizing direct solar irradiation as process energy for endothermic reactions inside reactor. LaGrange approach is used to inject coal particulates in the reactor which immediately undergoes devolatilization and finally steam (H2O) gasifier. Species transport equations are solved for the concentration of H2, CO2, CO, H2O and nitrogen (N2) as well as the heterogeneous reaction of char (C/fixed carbon) with steam. DO radiation model is applied to simulate 5KW of solar radiation through an optical window inside the reactor. Steady state mass and energy balance are solved to determine the reactor temperature and the composition of product syngas. The resulting problem is then simulated by finite volume method to solve governing mass, momentum, energy and species transport equation. Validation is accomplished by comparing the trends of simulated results with systematic analysis and experiment. The resultant H2: CO and CO: CO2 ratios are computed to be 1.83 and 9.42 respectively. The cold gas efficiency is calculated, which is found to be 105.21% showing the upgraded heating value of product gases by virtue of direct solar radiation read more... read less...

Keywords: CO2 emission, entrain flow gasifier, solar gasification, thermo-chemical

Concept of Overall Thermal Transfer Value (OTTV) in Design of Building Envelope to Achieve Energy Efficiency

IJTEE, volume-01 , Issue 2 (2010), PP 75 - 80

Published: 26 Jan 2010

DOI: 10.5383/ijtee.01.02.003

by J. Vijayalaxmi from Department of Architecture, School of Architecture and Planning, Anna University, Chennai, India- 600025

Abstract: Design of energy efficient buildings is the quickest way to reduce energy consumption. The skin of the building acts as a barrier between the indoor environment and the outdoor environment. The thermal performance of a building depends upon the façade design to a large extent, ranking second to the local climatic characteristics. Potential for energy conservation exists in all building typologies, but it becomes more of a concern in energy intensive buildings such as airconditioned offices and shopping malls. This paper discusses the significance of the Overall Thermal Transfer Value (OTTV) controls as a means of enhancing energy efficiency of buildings. OTTV is a measure of heat gain into the building through the building envelope. It also acts as an index for comparing the thermal performance of buildings. The objectives and need for OTTV controls are discussed. The parameters used in calculating OTTV and therefore the need to customize OTTV calculations based on the location of the building are analysed. The paper also discusses the OTTV standards in countries such as Singapore, Malaysia, Jamaica and Thailand. The application and calculation of OTTV for a case study building is demonstrated. The paper discusses the limitations of OTTV standards, its significance and relevance, and concludes that OTTV is one of the means of achieving energy efficiency of air-conditioned buildings. read more... read less...

Keywords: Air-Conditioned, Energy Efficiency, Energy Intensive, OTTV, Thermal Performance

Energy Rating Windows for Residential Buildings

IJTEE, volume-01 , Issue 2 (2010), PP 67 - 74

Published: 26 Jan 2010

DOI: 10.5383/ijtee.01.02.002

by K. Hassouneh, A. AlShboul, and A. Al-Salaymeh from Architecture Engineering Department, Faculty of Engineering & Technology, Univ. of Jordan, Amman 11942, Jordan, Mechanical Engineering Department, University of Jordan, Amman 11942, Jordan

Abstract: The present paper describes an example of an energy rating windows for residential buildings in Jordan. It focuses on the thermal properties of the available windows in the market in Jordan. Windows have a great effect on the heating and cooling requirements costs of a building, and the comfort level experienced by its occupants. Windows are considered the weakest link in a building envelope for heat gain in the summertime and heat loss in the wintertime. A survey on the most common windows that are used in residential buildings has been carried out. The label of the window describes the type of window, and rates it for many factors such as U-Factor, SHGC, and visible light transmittance. The output of the present work can give the home owners an opportunity to choose the appropriate window for the building taking into consideration thermal performance of the window and its impact on the cooling and heating load of the building. The energy performance of the building and the choice of energy efficient window are dependent on glazing type, number of glazing, frame materials, interior and exterior, shading, and window orientation. Therefore, it is very important to take into consideration all options when determining which energy-efficient window is best and most cost-effective for your needs both now and in the future. The most important reason to select energy efficient windows is to reduce the annual coast of heating and cooling of the buildings. This makes good sense for the most building owners and it also contributes in the efforts to reduce the bad impacts of the non- renewable energy use. read more... read less...

Keywords: Rating Windows, Residential Buildings, Energy Balance

Economic Analysis of Hybrid Renewable Model for Subtropical Climate

IJTEE, volume-01 , Issue 2 (2010), PP 57 - 65

Published: 26 Jan 2010

DOI: 10.5383/ijtee.01.02.001

by GM Shafiullah, Amanullah M.T. Oo, ABM Shawkat Ali, Dennis Jarvis, Peter Wolfs from Faculty of Sciences, Engineering & Health, CQ University, Australia, QLD-4702, Faculty of Arts, Business, Informatics & Education, CQ University, Australia, QLD-4702, Faculty of Science and Engineering, Curtin University of Technology, Australia, WA-6845

Abstract: Current power systems create environmental impacts due to utilization of fossil fuels, especially coal, as carbon dioxide is emitted into the atmosphere. In contrast to fossil fuels, renewable energy offers alternative sources of energy which are in general pollution free, technologically effective and environmentally sustainable. There is an increased interest in renewable energy, particularly solar and wind energy, which provides electricity without giving rise to carbon dioxide emissions. This paper presents economic analysis of a renewable hybrid system for a subtropical climate and also investigated the impact of renewable energy sources to the existing and future smart power system. The daily mean global solar irradiance and three hourly mean wind speeds have been collected from the Rockhampton Aero Weather Station, Queensland (RAWS), Australia for this study. Hybrid Optimization Model for Electric Renewable (HOMER), a computer model developed by National Renewable Energy Laboratory (NREL) has been used to perform comparative analysis of solar and wind energy with diesel and hybrid systems. Initially total net present cost (NPC), cost of energy (COE) and the renewable fraction (RF) have been measured as performances metrics to compare the performances of different systems. For better optimization, the model has been refined with sensitivity analysis which explores performance variations due to wind speed, solar irradiation and diesel fuel prices. From the simulation, it is shown that there are a number of factors that impact the integration and performance of renewable energy sources to the power systems. read more... read less...

Keywords: Renewable Energy, Smart Grid, HOMER, Performances Metrics, Sensitivity Analysis.

Renewable Energies: A Sustainable Future or a Prosperous Business

IJTEE, volume-01 , Issue 1 (2010), PP 51 - 55

Published: 22 Jan 2010

DOI: 10.5383/ijtee.01.01.008

by Ammar Moussi, Greg Asher from University of Biskra, Biskra, Algeria, 07000, University of Nottingham, Nottingham, UK, NG7-2RD

Abstract: Recent global developments appear to guarantee a market for green renewable energy. Among several sources of renewable energy currently explored, photovoltaic systems appear to be promising in view of their environmentally clean nature and the advantage of direct conversion to electrical power. In spite its high initial cost, solar energy production is rising steadily. Today's investment in the sector of renewable energy shows that a promising industry is being inaugurated. This paper discusses through the outcome of statistical and technical facts the paradoxical issues between environment sustainability and business development. read more... read less...

Keywords: Renewable energy, Sustainability, Investment

Wind Data Collection and Analyses at Masdar City for Wind Turbine Assessment

IJTEE, volume-01 , Issue 1 (2010), PP 43 - 50

Published: 22 Jan 2010

DOI: 10.5383/ijtee.01.01.007

by Isam Janajreh, Ilham Talab from Masdar Institute of Science and Technology, Abu Dhabi, P.O. Box 54224, United Arab Emirates

Abstract: Wind turbine technology has improved dramatically in the last two decades and their deployment and implementation increased by 20-25% annually. Wind is neither chaotically generated nor is based on random phenomenon. Wind is predictable to greater extend. Current predictive models lack the validation against collected historical data. In this work a 50m meteorological tower was installed at Masdar City for continuous collection of annual wind data records. Data is sampled at 10 minutes sampling rate using Campbell 1000 data logger connected to cup vane anemometry at 5 different heights to estimate the boundary layer profile. Collected and estimated wind energy density was below 120Watt/m2 suggesting low wind area and undermining the feasibility of wind turbine implementation in the city. Data is analysed for their first (mean and standard deviation) and second moments (correlation and spectrum) and found to vary considerably in scale and time suggesting simultaneous time and scale analysis. Wavelet analysis is used to study the intermittency of the wind data and quantify their intermittency factor read more... read less...

Keywords: Wind Energy, Wavelet Analysis, Frequency Spectrum

Solar Photocatalytic Degradation of Environmental Pollutants Using ZnO Prepared by Sol-Gel: 2, 4-Dichlorophenol as Case Study

IJTEE, volume-01 , Issue 1 (2010), PP 37 - 42

Published: 22 Jan 2010

DOI: 10.5383/ijtee.01.01.006

by Muneer M. Ba-Abbad, Abdul Amir H. Kadhum, Abu Bakar Mohamad, Mohd S. Takriff, Kamaruzzaman Sopian from Department of chemical and process engineering, Faculty of Engineering and Built Environment Universiti Kebangsaan Malaysia, Selangor, Malaysia, Solar Energy Research Institute (SERI),Universiti Kebangsaan Malaysia, Selangor, Malaysia

Abstract: The photocatalytic degradation of 2, 4-dichlorophenol (2,4DCP) in aqueous solution was carried out in batch process with ZnO prepared by sol-gel method. The effects of various factors, such as different calcinations temperatures and amount of catalyst were investigated for efficient degradation of 2, 4-dichlorophenol. The UV/Vis Spectrophotometer was used for analysing the concentration of 2, 4-dichlorophenol in solution at different time intervals during the experiment. The photocatalytic degradation of 2, 4-dichlorophenol was investigated by monitoring molecular absorbance at λ = 285 nm. The average solar intensity of ultra violet (UV) was recorded as 23 W/m2. The photocatalytic activity of the ZnO was evaluated by photocatalytic degradation of initial concentration 50 mg/l of 2, 4-dichlorophenol. Optimum value of catalyst dose was found to be 2 g/l. The experimental results showed that the photocatalytic degradation efficiency of 2, 4-dichlorophenol for 1 h irradiation time was up to 98 %. read more... read less...

Keywords: Solar photocatalytic , Sol-gel 2, 4-dichlorophenol

Energy Use, Energy Savings and Environmental Analysis of Industrial Boilers and Compressors

IJTEE, volume-01 , Issue 1 (2010), PP 29 - 36

Published: 22 Jan 2010

DOI: 10.5383/ijtee.01.01.005

by R. Saidur, M. Hasanuzzaman, N.A. Rahimb from Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia, Department of Electrical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia, Centre of Research UMPEDAC, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia

Abstract: In this paper energy use, energy and bill savings, emission reduction and pay period using highly efficient motor, variable speed drive by modulating speed of boiler and compressor has been estimated using energy audit data. It has been found that 68,923 MWh, 132,922 MWh, 78,769 MWh and 49,230 MWh of energy can be saved for 40%, 60%, 80% and 100% motor loadings, respectively for 20% speed reduction in the boiler system. Corresponding bill savings for the aforementioned energy savings have been found to be US$ 4,411,052, US$ 8,507,028, US$ 5,041,202, and US$ 43,150,751 for 40%, 60%, 80% and 100% motor loadings, respectively for 20% speed reduction in the boiler system. Energy savings and bill savings resulting from the use of high-efficiency motor in air compressor are 6703 MWh, 8251 MWh, and 10571 MWh, total energy, can be saved for 50%, 75%, and 100%, motor loadings, respectively. Similarly, bill savings for the preceding amounts of energy savings are US$ 428,984, US$ 528,042 and US$ 676,538, respectively. It is also clear that the use of high efficiency motor and VSDs leads to substantial energy savings and an enormous reduction in emissions. read more... read less...

Keywords: Energy, Energy savings, Environment, Boiler, Compressor.

Performance and Operational Experiences of Solar Driven Cooling Plant after Five Years in Operation

IJTEE, volume-01 , Issue 1 (2010), PP 23 - 28

Published: 22 Jan 2010

DOI: 10.5383/ijtee.01.01.004

by Ahmed Hamza H. Ali from Department of Energy Resources and Environmental Engineering, Egypt-Japan University of Science and Technology (E-JUST), P.O. Box 179, New Borg El-Arab City, Alexandria 21934, Egypt

Abstract: The main aim of this study is to report the performance evaluation as well as the gained operational experiences of a solar-driven cooling plant after 5 years in operation, in addition, based on the gained experiences, a suggestion for an appropriate small-scale solar-driven cooling plant for hot arid areas is presented. The plant includes a 35.17 KW cooling (10-RT) absorption chiller, vacuum tubes collectors with gross and net areas of 108 m2 and 72 m 2, a hot water storage capacity of 6.8 m 3, a cold-water storage capacity of 1.5 m3 and a 134-kW cooling tower. The plant provides air-conditioning for a floor space of 270 m 2. The plant performance results indicate: instead, small solar energy values at the plant location, the daily solar fraction ranged from 0.33 to 0.41, and for the duration from August 2002 to November 2007 the total solar energy supplied to the chiller is 53914 kWh and the total external energy (gas energy) supplied to the chiller is 35249 kWh and their percentage are about 60% and 40%, respectively. The collectors’ filed instantaneous mean efficiency value is about 0.63, the monthly average value varies from 34.1 % up to 41.8 %, with a five-year average value of 28.3 %, respectively and the daily chiller COP varies from 0.37 to 0.81, respectively. The gained from the operational experiences are: in hot arid areas, the water normally is rare, thus the re-cooling system should be designed based on dry re-cooling techniques. Moreover, based on the total initial capital cost of the entire solar cooling system, adsorption-cooling technology for small-scale solar-driven air-conditioning systems is the most appropriate. This is because these chillers can be driven by a low temperature energy source that can be obtained from flat plate collectors where, costs are a bit lower for flat plate collectors with liquid heat transfer carrier read more... read less...

Keywords: Solar cooling, Absorption chillers Lithium bromide-water operational experiences

Economic and Environmental Modeling of a Photovoltaic-Wind-Grid Hybrid Power System in Hot Arid Australia

IJTEE, volume-01 , Issue 1 (2010), PP 15 - 22

Published: 22 Jan 2010

DOI: 10.5383/ijtee.01.01.003

by G. Liu, M. G. Rasul, M. T. O. Amanullah, M. M. K. Khan from Power Engineering Research Group, Faculty of Sciences, Engineering and Health, CQ University, Queensland 4702, Australia

Abstract: Increased concern about energy crisis and environmental issues has revitalized interest in the application of renewable energy technologies. For ensuring steady and continuous electricity generations, a hybrid power system (HPS) including more than one renewable energy elements is introduced. In this paper, environmental and economic analyses are used to discuss the sustainability of a HPS. An investigation is made on small-scale operations of 100kWh per day HPS as a grid-assisted power generation consisting of solar (photovoltaic) and wind energy. A comparison is drawn among the different configurations of a grid-connected HPS operation focusing on environmental and economic impacts. Emissions and the renewable energy generation fraction (RF) of total energy consumption are calculated as the main environmental indicator. Costs including net present cost (NPC) and cost of energy (COE) are calculated for economic evaluation. To simulate long-term continuous implementation of the HPS, the hourly mean global solar radiation and wind speed data of 2007, from Alice Spring (23.70S, 133.88E) of Australia, are used as an example of a typical hot arid climate. The monthly solar exposure between 13.31 and 21.3 2 MJ m day and mean wind speed of 7.13 / in 2007 is considered for simulation The Micropower Optimization Model software HOMER developed by the National Renewable Energy Laboratory, USA is used for simulation. It is found that, for Alice Spring arid climates, the optimum results of HPS show a 64.3% reduction of emissions including CO2, 2 SO, and NO x. Renewable fraction of the optimized system is 54%. It is also found that the HPS has benefits of cost saving. The reduced NPC and COE are only equal to about 85.3% of energy consumption from standard grid. In addition, through a set of sensitivity analysis, it is found that the wind speed has more effects on the environmental and economic performance of a HPS under the specific climate. read more... read less...

Keywords: Environment; Economy; Hot Arid Australia; Hybrid Power System.

Effect of Façade Type on the Cooling Load of a Multi-Storey Building

IJTEE, volume-01 , Issue 1 (2010), PP 9 - 14

Published: 07 Sep 2010

DOI: 10.5383/ijtee.01.01.002

by Rafat Al-Waked from College of Engineering, Prince Mohammad Bin Fahd University (PMU), Al Khobar, Kingdom of Saudi Arabia, 31952

Abstract: The thermal and energy implications of a number of façade configurations on the lowest potential energy consumption for a multi-storey building have been investigated using the IES Virtual Environment software package. A preliminary 3-Dimensional computer model of the building was created and a number of different analyses were undertaken to ascertain the optimum façade configuration from an occupant comfort and thermal energy consumption perspective. Results have demonstrated that any one façade or glazing type will not provide the best solution in terms of peak loads, overall energy consumption, occupant comfort and cost. Any solution must therefore be a compromise between these competing factors. On the basis of these results, it has been found that a higher performance glazing results in the lowest peak cooling load, however, a more moderate performance glazing results in the best overall energy consumption. read more... read less...

Keywords: Passive Cooling, Thermal Analysis, Energy Performance, Window Glazing

Solar Energy to Drive Half-Effect Absorption Cooling System

IJTEE, volume-01 , Issue 1 (2010), PP 1 - 8

Published: 22 Jan 2010

DOI: 10.5383/ijtee.01.01.001

by Rabah GOMRI from Laboratory of Génie Climatique, Engineering Faculty, Department of Génie Climatique 25000, Constantine, Algeria

Abstract: This paper presents the simulation results and an overview of the performance of low capacity two stage half-effect absorption cooling system (10kW), suitable for residential and small building applications. The primary heat source is solar energy supplied from flat plate collectors. The complete system (solar collectors-absorption cooling system) was simulated using a developed software program. The energy and exergy analysis are carried out for each component of the system. All exergy destructed that exist in this solar cooling system is calculated. Critical temperatures which are the minimum allowable hot water inlet temperatures are determined. This system has shown promising characteristics. When the condenser temperature is fixed at 28°C, 32°C and 36°C it can be concluded that between time of day 10 and 14 solar collector provides about 96%, 95% and 91% heating energy required respectively with a cover of about 100% between time of day 11 and 13 which correspond to a maximum of solar radiation. The daily cover is about 71%, 70% and 65% respectively. read more... read less...

Keywords: Absorption cooling system Performance; Solar energy Two stage Half-effect system.