Thermodynamical research of using solar energy for desalination of seawater

Many regions of the world face the problem of saline water. Water desalination processes, which require significant energy consumption, are a common solution to produce drinking water. This study evaluated the influence of the following process operational parameters on the energy consumption of seawater reverse osmosis systems: water salinity, permeate recovery ratio, membrane performance, and feed water temperature. Optimal operational conditions for the theoretical minimum energy consumption were determined with experiments by varying water qualities and operational parameters. In order to further reduce energy consumption a reverse osmosis system was integrated with a photovoltaic solar system and a pilot photovoltaic reverse osmosis system was built and tested The results obtained from this study indicated that even though a solar photovoltaic system incurs a huge initial capital investment, it will yield significant benefits in the long run of the reverse osmosis operational perio

Effect of thermal energy storage in energy consumption required for air conditioning system in office building under the african mediterranean climate

In the African Mediterranean countries, cooling demand constitutes a large proportion of total electrical demand for office buildings during peak hours. The thermal energy storage systems can be an alternative method to be utilized to reduce and time shift the electrical load of air conditioning from on-peak to off-peak hours. In this study, the Hourly Analysis Program has been used to estimate the cooling load profile for an office building based in Tripoli weather data conditions. Preliminary study was performed in order to define the most suitable operating strategies of ice thermal storage, including partial (load leveling and demand limiting), full storage and conventional A/C system. Then, the mathematical model of heat transfer for external ice storage would be based on the operating strategy which achieves the lowest energy consumption. Results indicate that the largest rate of energy consumption occurs when the conventional system is applied to the building, while the lowest rate of energy consumption is obtained when the partial storage (demand limiting 60%) is applied. Analysis of results shows that the new layer of ice formed on the surface of the existing ice lead to an increase of thermal resistance of heat transfer, which in return decreased cooling capacity

Thermodynamical research of using solar energy for desalination of seawater

Many regions of the world face the problem of saline water. Water desalination processes, which require significant energy consumption, are a common solution to produce drinking water. This study evaluated the influence of the following process operational parameters on the energy consumption of seawater reverse osmosis systems: water salinity, permeate recovery ratio, membrane performance, and feed water temperature. Optimal operational conditions for the theoretical minimum energy consumption were determined with experiments by varying water qualities and operational parameters. In order to further reduce energy consumption a reverse osmosis system was integrated with a photovoltaic solar system and a pilot photovoltaic reverse osmosis system was built and tested The results obtained from this study indicated that even though a solar photovoltaic system incurs a huge initial capital investment, it will yield significant benefits in the long run of the reverse osmosis operational perio

Effect of thermal energy storage in energy consumption required for air conditioning system in office building under the african mediterranean climate

In the African Mediterranean countries, cooling demand constitutes a large proportion of total electrical demand for office buildings during peak hours. The thermal energy storage systems can be an alternative method to be utilized to reduce and time shift the electrical load of air conditioning from on-peak to off-peak hours. In this study, the Hourly Analysis Program has been used to estimate the cooling load profile for an office building based in Tripoli weather data conditions. Preliminary study was performed in order to define the most suitable operating strategies of ice thermal storage, including partial (load leveling and demand limiting), full storage and conventional A/C system. Then, the mathematical model of heat transfer for external ice storage would be based on the operating strategy which achieves the lowest energy consumption. Results indicate that the largest rate of energy consumption occurs when the conventional system is applied to the building, while the lowest rate of energy consumption is obtained when the partial storage (demand limiting 60%) is applied. Analysis of results shows that the new layer of ice formed on the surface of the existing ice lead to an increase of thermal resistance of heat transfer, which in return decreased cooling capacity

Modeling of transport processes in the cigarette principle combustion furnace

This paper presents numerical and experimental investigations of complex and interrelated physical and chemical phenomena that occur during combustion of baled soybean residue in the furnace with the cigarette type of combustion. The result of comprehensive research is reactive flow model of biomass combustion inside furnace. Model is described by set of PDE which define momentum, heat and mass transfer processes in porous and fluid system. The main aim of developed CFD model is numerical simulation of combustion process inside the cigarette furnace. It is also used to provide deeper insight in complex processes occurring during biomass combustion. Verification of proposed numerical model was performed through comprehensive experimental tests on the experimental-industrial plant of 1.5 MW boiler for heating the greenhouses in the Agricultural Corporation in Belgrade. The tests included measurement of flow rate and air and flue gas temperature input and output values on the furnace that are taken as the boundary conditions of the developed model. Comparison of the experimental results shows satisfactory agreement with numerical results (the maximum relative deviation of calculation and measurement temperatures are 10-45%), therefore the developed mathematical model could be used to analyse the effects of structural and parametric (fuel composition, power rate, air excess etc.) changes of the facility, from the standpoint of energy efficiency and ecology

Evaluation of heating efficiency and thermal comfort in special purpose vehicle cabins

The paper presents the integrated application of two methods during testing HVAC system efficiency in the cabins of HUMMER.1151A1 and OAR 1RL-128D offroad vehicles. Spatial measurements of change in air temperature per time have been performed at three vertical levels (head, knees, and feet) of the driver and passengers, which totals to 15 measuring points per vehicle. The main goal of testing was to evaluate accurately the efficiency of heating and cooling in relation time interval required to attain a designed temperature of comfort in the vehicle cabin, on condition that the difference in ambient temperature levels does not exceed 10 degrees C. With a view to more efficient evaluation of thermal comfort in vehicle cabins, the testing was performed also of predicted mean vote and predicted percentage of dissatisfied indices. Standard thermal comfort surveys ask subjects about their thermal sensation on a seven-point scale from cold (-3) to hot (+3). This research is carried out according to the methods based on ISO 7730, ASHRAE 55, and SORS 8419 standards

Evaluation of heating efficiency and thermal comfort in special purpose vehicle cabins

The paper presents the integrated application of two methods during testing HVAC system efficiency in the cabins of HUMMER.1151A1 and OAR 1RL-128D offroad vehicles. Spatial measurements of change in air temperature per time have been performed at three vertical levels (head, knees, and feet) of the driver and passengers, which totals to 15 measuring points per vehicle. The main goal of testing was to evaluate accurately the efficiency of heating and cooling in relation time interval required to attain a designed temperature of comfort in the vehicle cabin, on condition that the difference in ambient temperature levels does not exceed 10 degrees C. With a view to more efficient evaluation of thermal comfort in vehicle cabins, the testing was performed also of predicted mean vote and predicted percentage of dissatisfied indices. Standard thermal comfort surveys ask subjects about their thermal sensation on a seven-point scale from cold (-3) to hot (+3). This research is carried out according to the methods based on ISO 7730, ASHRAE 55, and SORS 8419 standards

Experimental determination of the balled soya residue permeability

Biomasa kao najznačajniji obnovljivi izvor energije kod nas, ima značajne prednosti sa aspekta očuvanja životne sredine, jer se njenim korišćenjem ne povećava koncentracija ugljendioksida u atmosferi, što se u potpunosti uklapa u tendencije zemalja potpisnica Kjoto sporazuma, među kojima je i Republika Srbija. U skladu s tim, grupa saradnika Laboratorije za termotehniku i energetiku Instituta za nuklearne nauke 'Vinča', niz godina unazad značajno radi na promovisanju korišćenja otpadne poljoprivredne biomase, što je finalizovano razvojem kotla snage 1,5 MW za sagorevanje baliranog sojinog ostatka za potrebe grejanja 1 hektara plastenika u okviru Poljoprivrednog kombinata Beograd. Za potrebe definisanja termofizičkih karakteristika goriva (bali- ranog sojinog ostatka) koje su od posebnog značaja za sveobuhvatnije sagledavanje i predviđanje procesa sagorevanja, u ovom radu je prikazano eksperimentalno određivanje koeficijenata permeabilnosti. Koeficijenti su određivani tako da odgovaraju viskoznim i inercionim članovima uopštene Forhajmerove jednačine. Eksperimentalnim istraživanjima je obuhvaćen uticaj poroznosti na permeabilnost, a kao rezultat analize eksperimentalnih podataka, definisane su i funkcionalne zavisnosti pomenutih koeficijenata od poroznosti. Pored toga, u radu je razmatran i uticaj vlažnosti biomase na permeabilnost, kao i funkcionalna zavisnost vlažnosti i poroznosti. Određivanje parametara permeabilnosti, kao i njihove zavisnosti od uticajnih faktora (poroznost i vlažnost), polazne su osnove u daljem istraživanju kinetike procesa sagorevanja u realnim uslovima, što je veoma značajno pri definisanju geometrijskih karakteristika ložišta.Biomass as the most important renewable energy source in our country has also significant advantages from the aspect of environment protection. The later is because its use does not increase the concentration of carbon dioxide in the atmosphere, what is completely in accordance with the tendencies of the signatory countries of the Kyoto Agreement, including the Republic of Serbia. Accordingly, a group of associates of the Laboratory for Thermal Engineering and Energy of the Vinča Institute of Nuclear Sciences, Belgrade, a large number of years has invested huge efforts into promoting the use of agricultural waste biomass. These efforts finished with the development of 1.5 MW power boiler combustion balled soybean residue for 1 ha heating greenhouses in the Agricultural complex Belgrade. For purposes of defining the thermophysical properties of fuel (balled soybean residue), which are of great importance for the comprehensive understanding and prediction of the combustion process, this work has been shown experimental determination of the permeability coefficients in Forchheimer's equation which presents the pressure drop through porous media. Coefficients were determined to match the viscous and inertia terms of the general Forchheimer's equation. Experimental research include influence of porosity on permeability analysis, and accordingly, the semi-empirical dependence of these coefficients of porosity has been given. In addition, the paper also has discussed the influence of humidity on the permeability of biomass, and the dependence on moisture and porosity, as well. The determination of permeability parameters, and their dependence of the relevant factors (porosity and humidity), is the starting base for the further study of the combustion process kinetics under real conditions, what is very important for the defining combustion chamber construction features