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Abstract: Pump is main equipment in air conditioning systems and used widely, but its energy consumption is great. In order to improve energy efficiency, using pump controlled by frequency-conversion technology is an effective method. In this paper, the working principle and control method of variable frequency pump is described in detail, and gives a comparison between variable frequency control and traditional control about energy saving effect. Because traditional PID controller can be hard to get good control performance in pump control, this paper presents a control method using fuzzy logic controller to achieve frequency conversion and constant pressure water supply. The controlled variable is obtained by fuzzy control table. The system has energy-saving, security, and stable water pressure, etc. Simulation results show that the proposed controller not only have good robustness, but also have good dynamic and static performance. [Copyright &y& Elsevier]

Abstract: Energy efficient HVAC solutions may be obtained by combining different energy sources – fossil and renewable – into single hybrid systems. This leads to a variety of system concepts with specific boundary conditions. As a consequence, the definition of a unique representation method and a standardized performance evaluation procedure is a challenging task. Currently, two international projects promoted by the IEA are dealing with the representation and the performance calculation of a particular category of hybrid systems, i.e. integrated solar assisted systems. The HPP Annex 34 “Thermally Driven Heat Pumps for Heating and Cooling”, whose goal is to reduce the environmental impact of heating and cooling by the use of thermally driven heat pumps, has solar cooling as one of the systems under investigation. The joint project between SHC and HPP Task 44/Annex 38 “Solar and Heat Pump Systems” is focused on different system combinations of solar thermal collectors and heat pumps. The scope of the present paper is to show a systematic methodology to represent and evaluate the energy performance of complex hybrid systems. The proposed approach is a joint effort of the on-going IEA activities and will be discussed regarding the mentioned solar hybrid systems. However, the final goal of the work is to provide a basis for a simple, fair and transparent comparison of all systems for heating and cooling, regardless of the technology. [Copyright &y& Elsevier]

Abstract: In Kuwait, electricity is becoming an increasingly essential element of modern life. This flexible energy is used for heating, cooling, appliances, TVs, computers and transportation. The demand for electricity is growing at an average of 5.4% per year well above the world average of 2.7%. The growth of Kuwait energy demand is projected to rise sharply over coming years. The Ministry of Electricity and Water (MEW) expects that the peak demand will grow to 17.2 GW by the year 2013. The chilled water thermal storage (CWTS) system is one of the available techniques that can be utilized to reduce peak electricity demand of buildings when national electricity consumption is at its highest level. In this paper, Life Cycle Cost (LCC) was estimated to investigate impact of implementing CWTS for cooling of buildings for both the MEW and the consumer. Results show that CWTS operating with a load leveling strategy gives the lowest LCC compared to 50% demand limiting and full storage strategies, and is, therefore, considered as the most cost effective option for both MEW and consumer. [Copyright &y& Elsevier]

Abstract: In order to utilize clean energy such as solar energy to reduce electricity consumption in heating, ventilating, air conditioning and refrigerating (HVAC&R) engineering, the author developed a new style diffusion-absorption refrigerator (DAR) with solution pumps. It can be driven by low-temperature heat sources, in which LiNO3-NH3-He is used as working fluids and an adiabatic spray absorber with a plate-type solution cooler is designed to enhance the mass and heat transfer, respectively. This paper is mainly concern on the principle and operating performance of the DAR, especially the relationships of evaporator temperature (Te), absorber temperature (Ta) and parameters such as the volume flow rate and inlet temperature of LiNO3-NH3 solution sprayed from the top of the adiabatic spray absorber. Based on measured data and theoretical analysis, the solution circulation ratio is also presented. Analyses indicate that in this DAR system, Te mainly depends on Ta rather than condenser temperature (Tc) and generator temperature (T g ). Thus Te and the performance of the DAR can be modulated by changing parameters of the sprayed solution. The results show that this DAR system can be driven by solar energy to meet the requirements of air conditioning, freezing or else. A typical operating experiment shows when temperatures of heat source (hot water temperature Tws), Tg, Ta and Tc are 92.7°C, 87.0°C, 29.6°C and 21.6°C, respectively, the lowest Te is -13.0°C, the corresponding refrigeration capacity and coefficient of performance (COP) are 1.9kW and 0.156, respectively. [Copyright &y& Elsevier]

Abstract: For various reasons, sustainability today is producing an important and interesting approach between architecture and the environment. This is taking place in forms and with different degrees of intensity. Within the challenges of energy crisis and climatic changes architects started to develop new approaches to address the quest of energy demands in buildings. One of these approaches is façade greening which started to take an important place in the last 10 years, it''s not considered a new innovation, where applying green facade is not a new concept; however it has not been approved as an energy saving method for the built environment. Vertical greening can provide a cooling potential on the building surface, which is very important during summer periods in hot climates. The cooling effect of green facades has also an impact on the inner climate in the building by preventing warming up the façade. Within this quest, this paper is focused on the analysis of the effect of green facades systems on the building temperature and addressing different types of green facades systems and their thermal effect. [Copyright &y& Elsevier]

Abstract: There is abundant high-energy-grade residual heat on ships. The rotary desiccant air-conditioning (A/C) system can recover ship''s residual heat to work as the system''s driving heat source, achieving significant energy-saving for ship''s A/C. In this paper a new two-wheel two-stage rotary desiccant A/C system was developed for a ship. According to operating parameters of a real ship, the ship''s available residual heat and the required amount of steam consumption for the rotary desiccant A/C system developed were analyzed; and the system''s energy-saving was calcualted. The analysis results showed that the maximum amount of steam generated by residual-heat boiler on the ship is enough to meet the need to drive the marine rotary desiccant A/C system and the need of daily use and fuel oil heating. Compared with the traditional marine A/C system, the new marine rotary desiccant A/C system can save about 33.4% of energy consumption. [Copyright &y& Elsevier]

Abstract: Ground-source heat pump (GSHP) is a renewable energy technology with the advantages of energy saving and environmental friendliness. This paper focuses on the energy efficiency of air-conditioning systems in public buildings in Tianjin. Three public buildings are chosen as case studies with different forms of cold & heat sources. A building with ground-source heat pump for heating and cooling, a building with electricity-driven refrigerating unit for cooling and centralized heat-supply network for heating, a building with direct-fired Li-Br absorption refrigerating and heating unit for heating and cooling are selected. Attempt is made to analyze the actual operating performance of air-conditioning system and evaluate the system energy efficiency in different buildings. The results show that ground-source heat pump air-conditioning system without adequate design and management is not always better than other traditional air-conditioning systems. [Copyright &y& Elsevier]

Abstract: With the application of central air-conditioning systems increasing, the problems of its energy consumption and controlling environmental comfort attract more attention. Enthalpy control uses less energy than temperature control, and can meet the requirements of environmental comfort. This paper introduces the definition of enthalpy, enthalpy control principles and methods and so on, and describes the enthalpy control of central air-conditioning systems in detail. Fuzzy logic control method is proposed for the room temperature and three-dimensional fuzzy control structure is constructed. According to the errors in relative humidity, control rules are divided into three parts to achieve automatic control of room temperature. Simulation results show that the proposed controller has good robustness, and better static and dynamic characteristics than the traditional controller. [Copyright &y& Elsevier]

Abstract: This paper presents an investigation of a direct evaporative air cooler (DEAC) under Algerian climate, at the city of BECHAR. We carried out the theory and design of the DEAC. Simulation is done for an evaporative air cooler for three successive months June, July and August under TRNSYS environment. Measured weather data of the selected site are generated by METEONORM software. Result showed that the maximum depression of the dry bulb temperature reached is about 18.86°C and the Energy Efficiency Ratio (EER) is calculated. Evaporative cooling equipments work well in the hot and arid southern regions, which constitute practically the two third of the country. They have no impact whatsoever on the environment. Energy consumption is much less than in classical air conditioning units this is why these systems can be powered by solar photovoltaic panels. [Copyright &y& Elsevier]