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Climate change is an increasingly important global concern at this moment. Fossil fuels meet a majority of world energy needs and because buildings are large energy consumers, they are also a major contributor to global carbon emissions and greenhouse gas (GHG) production. It's important for the European Union, including Romania to avoid these problems. Buildings are responsible for 40% of energy consumption and 36% of CO 2 emissions in the EU, according to United Nations Environment Programme (UNEP). The construction sector is developing since 2013 so in the future the energy consumption will increase very fast. As a result, renewable energy sources represent one of the main directions in reducing conventional energy consumption in buildings. In this paper the authors analyze solutions for decreasing the energy consumption required by the air-conditioning system in an office building of 6466m2, located in Bucharest. The current air conditioning solutions are the classical ones, based on either fan coils, supplied with chilled water of 12/7 °C, or air-coolers, as part of an Air Handling Unit (AHU). In the latter case, the cooled water is prepared by a vapor compression refrigeration unit chiller of 190 kW cooling capacity, working with R22. The solutions analyzed in this paper consider each of the following alternatives: a. Heat recovery from the exhausted air by using a heat exchanger integrated in the AHU; b. Replacement of the vapor compression refrigeration unit chiller with an one stage lithium bromide/water absorption refrigeration unit driven bysolar energy; c. Coupling the above mentioned solutions. All these solutions are discussed and analyzed from both technical and economical points of view. [ABSTRACT FROM AUTHOR]

This paper reports theoretical and experimental results on ammonia heat and mass transfer coefficient in evaporative condensers. The theoretical study, based on the review performed by the authors, uses currently available correlations in open literature and presents modeling results. The experimental study was carried out on specially designed set-ups that allowed both measuring and acquisition of data and aimed to determine: mass transfer coefficient at water/air interface; heat transfer coefficient at tube wall/water interface; heat transfer coefficient at condensing refrigerant/tube wall interface. Experimental and theoretical values were further compared, in order to validate the correlations used, under specific geometrical configuration of the evaporative condenser under study and specific operating conditions. The paper concluded that all correlations used describe, more or less accurately, the heat and mass transfer process in ammonia evaporative condensers and performs a comparative analysis of the results, based on deviation shown with respect to experimental values. The paper also addresses the current ecological aspect implied by refrigerants, by choosing ammonia, a natural, environmentally friendly refrigerant, known for its zero ozone depleting potential and zero global warming effect. [ABSTRACT FROM AUTHOR]

This paper reports experimental data obtained for ammonia condensation heat transfer in an evaporative condenser. Experiments were carried out on a specially designed set-up equipped with both measuring and control devices, and a data acquisition system. Experiments were conducted for ammonia saturation temperature of 22°C to 40°C and condenser heat rejection rate ranging from 2000W to 6000W, during steady state condensation of ammonia. The experimental investigation aimed to determine thermal performances of the ammonia evaporative condenser under different operating conditions, namely as a function of: temperature difference between ammonia condensation and inlet air wet bulb temperature, cooling water mass flow rate and ammonia mass flow rate. Water film temperature distribution along the condenser's height has also been studied. Experimental results have been further compared to data in the open literature by authors with similar experimental investigations. The paper concluded that experimental results are in fairly good agreement with other authors work and consequently reliable. The paper also addresses the current ecological aspect implied by refrigerants, by using ammonia. Apart from its attractive thermo-physical properties, as compared to HFCs, ammonia is also an environment friendly natural refrigerant, known for its zero ozone depleting potential and zero global warming effect. [ABSTRACT FROM AUTHOR]

Climate change is an increasingly important global concern at this moment. Fossil fuels meet a majority of world energy needs and because buildings are large energy consumers, they are also a major contributor to global carbon emissions and greenhouse gas (GHG) production. It's important for the European Union, including Romania to avoid these problems. Buildings are responsible for 40% of energy consumption and 36% of CO2 emissions in the EU, according to United Nations Environment Programme (UNEP). The construction sector is developing since 2013 so in the future the energy consumption will increase very fast. As a result, renewable energy sources represent one of the main directions in reducing conventional energy consumption in buildings. In this paper the authors analyze solutions for decreasing the energy consumption required by the airconditioning system in an office building of 6466 m², located in Bucharest. The current air conditioning solutions are the classical ones, based on either fan coils, supplied with chilled water of 12/7 °C, or air-coolers, as part of an Air Handling Unit (AHU). In the latter case, the cooled water is prepared by a vapor compression refrigeration unit chiller of 190kW cooling capacity, working with R22. The solutions analyzed in this paper consider each of the following alternatives: a. Heat recovery from the exhausted air by using a heat exchanger integrated in the AHU; b. Replacement of the vapor compression refrigeration unit chiller with an one stage lithium bromide/water absorption refrigeration unit driven by solar energy; c. Coupling the above mentioned solutions. All these solutions are discussed and analyzed from both technical and economical points of view. [ABSTRACT FROM AUTHOR]

This paper reports experimental data obtained for ammonia condensation heat transfer in an evaporative condenser. Experiments were carried out on a specially designed set-up equipped with both measuring and control devices, and a data acquisition system. Experiments were conducted for ammonia saturation temperature of 22°C to 40°C and condenser heat rejection rate ranging from 2000W to 6000W, during steady state condensation of ammonia. The experimental investigation aimed to determine thermal performances of the ammonia evaporative condenser under different operating conditions, namely as a function of: temperature difference between ammonia condensation and inlet air wet bulb temperature, cooling water mass flow rate and ammonia mass flow rate. Water film temperature distribution along the condenser's height has also been studied. Experimental results have been further compared to data in the open literature by authors with similar experimental investigations. The paper concluded that experimental results are in fairly good agreement with other authors work and consequently reliable. The paper also addresses the current ecological aspect implied by refrigerants, by using ammonia. Apart from its attractive thermo-physical properties, as compared to HFCs, ammonia is also an environment friendly natural refrigerant, known for its zero ozone depleting potential and zero global warming effect. [ABSTRACT FROM AUTHOR]

This paper reports theoretical and experimental results on ammonia heat and mass transfer coefficient in evaporative condensers. The theoretical study, based on the review performed by the authors, uses currently available correlations in open literature and presents modeling results. The experimental study was carried out on specially designed set-ups that allowed both measuring and acquisition of data and aimed to determine: mass transfer coefficient at water/air interface; heat transfer coefficient at tube wall/water interface; heat transfer coefficient at condensing refrigerant/tube wall interface. Experimental and theoretical values were further compared, in order to validate the correlations used, under specific geometrical configuration of the evaporative condenser under study and specific operating conditions. The paper concluded that all correlations used describe, more or less accurately, the heat and mass transfer process in ammonia evaporative condensers and performs a comparative analysis of the results, based on deviation shown with respect to experimental values. The paper also addresses the current ecological aspect implied by refrigerants, by choosing ammonia, a natural, environmentally friendly refrigerant, known for its zero ozone depleting potential and zero global warming effect. [ABSTRACT FROM AUTHOR]