The aim of this paper is to explore a method to reduce the energy consumption of the air-cooled v... more The aim of this paper is to explore a method to reduce the energy consumption of the air-cooled vapour compression air conditioning system by using the evaporative-cooled condenser (ECC) technique. By pre-cooling the air before it reaches the condenser coil, the condenser is able to reject more heat. As a result, cooling capacity increases while energy consumption falls. The applicability, limitation and energy performance of this strategy is discussed. Mathematical models of the system components are firstly developed. An actual direct expansion (DX) rooftop package of a commercial building located in the hot and dry climate conditions is used for experimentation and data collection. The system under investigation is extensively equipped with a number of instrumentation devices for data logging. Both inputs and outputs are known and measured from field monitoring in one summer week. The performance of the proposed method is simulated using a transient simulation software package. The integrated simulation tool was validated by comparing predicted and measured power consumption of the rooftop package. Results show that up to 28% power savings can be obtained using this approach.
This paper aims to analyse the performance of a new solar-assisted direct expansion air-condition... more This paper aims to analyse the performance of a new solar-assisted direct expansion air-conditioner and to demonstrate its capability of energy savings and ecological conservation. Here, an integrated flat collector storage system as well as an immersed piped coil is equipped with the direct expansion evaporator to raise the superheat temperature entering the variable speed compressor, causing a smaller duty cycle of the compressor and a slight increase in its suction pressure, and hence, reduce its energy consumption. Water in the flat solar collector is in contact with the collector’s absorbing surface and therefore, heat is transferred to the water and then to the refrigerant in the immersed heat exchanger. Once the room has achieved its desired temperature, the compressor turns off while room cooling will continue until the refrigerant pressure within the circulation loop fails to maintain the desired temperature. The system advantage is that heat can be imparted into the refrig...
Building Services Engineering Research and Technology, 2015
The effective design of an energy efficient heating, ventilation and air conditioning system is r... more The effective design of an energy efficient heating, ventilation and air conditioning system is reliant on multiple components. Among others, the air-handling unit cooling coil and its ability to perform efficiently directly influences heating, ventilation and air conditioning system performance. This paper investigates the energy and thermal performance of a water-cooled central cooling plant when combined with a direct evaporative cooling system located between the cooling tower and cooling coil of the air-handling unit. The evaporative cooler uses the water made by cooling tower to reduce the temperature of the 100% ambient air. The cooled air then passes through the cooling coil. This paper will demonstrate a series of mathematical models of the system components and validate them against experimental results. For this purpose, the central cooling plant is extensively equipped with a number of sensors and instrumentation devices for experimentation and data collection. The influence of the evaporative cooler on the energy saving potential and thermal comfort of the central cooling plant is evaluated. The advantages of this proposed hybrid system rests with the fact that the refrigeration effect of the chiller’s evaporator is decreased, which causes reduction of compressor power consumption. Results show that the hybrid system can provide average monthly energy savings between 11% and 24%, while enhancing the comfort level inside the building. Practical application : With traditional heating, ventilation and air conditioning systems contributing to 40% of a building’s overall energy consumption, the public’s increasing reliance on them as a necessity rather than a luxury is an issue in urgent need of attention. This together with a growing demand for cost-effective infrastructure and appliances has necessitated new installations and major retrofits in occupied buildings to achieve energy efficiency and environmental sustainability. The aim of this paper is to present a new integrated heating, ventilation and air conditioning system to meet these requirements without compromising comfort and indoor air quality.
2011 IEEE/SICE International Symposium on System Integration (SII), 2011
Cooling systems in buildings are required to be more energy-efficient while maintaining the stand... more Cooling systems in buildings are required to be more energy-efficient while maintaining the standard air quality. The aim of this paper is to explore the potential of reducing the energy consumption of a central air-conditioned building taking into account comfort conditions. For this, we propose a new hybrid evaporative cooling system for HVAC efficiency improvement. The integrated system will be
ABSTRACT The purpose of this study is to develop an optimization methodology for the detailed ene... more ABSTRACT The purpose of this study is to develop an optimization methodology for the detailed energy and cost effective design of a finned-tube condenser coil in order to enhance the system performance. Using this method, the frontal area of the condenser coil is maintained as constant, while other geometrical parameters of the thermal and economic performance of the system are varied and investigated. An existing air-cooled direct expansion (DX) rooftop package unit of a real-world commercial building is used for experimental data collection. First, the theoretical–empirical model for the system components is developed. Based on mathematical models and using collected data, a numerical algorithm is developed and embedded in a transient simulation tool. The integrated simulation tool is then validated by using the wide range of operating data obtained experimentally from the cooling plant during summer time. Furthermore, a mixed heuristic–deterministic optimization algorithm was implemented to determine the synthesis and design variables that influence the cost and energy efficiency of each configuration. Different new designs for condenser coil were then constructed to evaluate the potential of design improvements. Afterwards, the computer model was used to predict how changes in condenser coil geometry would affect the cost and energy consumption of the system.
ABSTRACT Decreasing the energy consumption of heating, ventilation and air conditioning (HVAC) sy... more ABSTRACT Decreasing the energy consumption of heating, ventilation and air conditioning (HVAC) systems is becoming increasingly important due to rising cost of fossil fuels and environmental concerns. Therefore, finding novel ways to reduce energy consumption in buildings without compromising comfort and indoor air quality is an ongoing research challenge. One proven way of achieving energy efficiency in HVAC systems is to design systems that use novel configurations of existing system components. Each HVAC discipline has specific design requirements and each presents opportunities for energy savings. Energy efficient HVAC systems can be created by re-configuring traditional systems to make more strategic use of existing system parts. Recent research has demonstrated that a combination of existing air conditioning technologies can offer effective solutions for energy conservation and thermal comfort. This paper investigates and reviews the different technologies and approaches, and demonstrates their ability to improve the performance of HVAC systems in order to reduce energy consumption. For each strategy, a brief description is first presented and then by reviewing the previous studies, the influence of that method on the HVAC energy saving is investigated. Finally, a comparison study between these approaches is carried out.
The purpose of this study is to develop an optimization methodology for the detailed energy and c... more The purpose of this study is to develop an optimization methodology for the detailed energy and costeffective design of a finned-tube condenser coil in order to enhance the system performance. Usingthis method, the frontal area of the condenser coil is maintained as constant, while other geometricalparameters of the thermal and economic performance of the system are varied and investigated. Anexisting air-cooled direct expansion (DX) rooftop package unit of a real-world commercial building isused for experimental data collection. First, the theoretical–empirical model for the system componentsis developed. Based on mathematical models and using collected data, a numerical algorithm is devel-oped and embedded in a transient simulation tool. The integrated simulation tool is then validated byusing the wide range of operating data obtained experimentally from the cooling plant during sum-mer time. Furthermore, a mixed heuristic–deterministic optimization algorithm was implemented todet...
The aim of this paper is to explore a method to reduce the energy consumption of the air-cooled v... more The aim of this paper is to explore a method to reduce the energy consumption of the air-cooled vapour compression air conditioning system by using the evaporative-cooled condenser (ECC) technique. By pre-cooling the air before it reaches the condenser coil, the condenser is able to reject more heat. As a result, cooling capacity increases while energy consumption falls. The applicability, limitation and energy performance of this strategy is discussed. Mathematical models of the system components are firstly developed. An actual direct expansion (DX) rooftop package of a commercial building located in the hot and dry climate conditions is used for experimentation and data collection. The system under investigation is extensively equipped with a number of instrumentation devices for data logging. Both inputs and outputs are known and measured from field monitoring in one summer week. The performance of the proposed method is simulated using a transient simulation software package. The integrated simulation tool was validated by comparing predicted and measured power consumption of the rooftop package. Results show that up to 28% power savings can be obtained using this approach.
This paper aims to analyse the performance of a new solar-assisted direct expansion air-condition... more This paper aims to analyse the performance of a new solar-assisted direct expansion air-conditioner and to demonstrate its capability of energy savings and ecological conservation. Here, an integrated flat collector storage system as well as an immersed piped coil is equipped with the direct expansion evaporator to raise the superheat temperature entering the variable speed compressor, causing a smaller duty cycle of the compressor and a slight increase in its suction pressure, and hence, reduce its energy consumption. Water in the flat solar collector is in contact with the collector’s absorbing surface and therefore, heat is transferred to the water and then to the refrigerant in the immersed heat exchanger. Once the room has achieved its desired temperature, the compressor turns off while room cooling will continue until the refrigerant pressure within the circulation loop fails to maintain the desired temperature. The system advantage is that heat can be imparted into the refrig...
Building Services Engineering Research and Technology, 2015
The effective design of an energy efficient heating, ventilation and air conditioning system is r... more The effective design of an energy efficient heating, ventilation and air conditioning system is reliant on multiple components. Among others, the air-handling unit cooling coil and its ability to perform efficiently directly influences heating, ventilation and air conditioning system performance. This paper investigates the energy and thermal performance of a water-cooled central cooling plant when combined with a direct evaporative cooling system located between the cooling tower and cooling coil of the air-handling unit. The evaporative cooler uses the water made by cooling tower to reduce the temperature of the 100% ambient air. The cooled air then passes through the cooling coil. This paper will demonstrate a series of mathematical models of the system components and validate them against experimental results. For this purpose, the central cooling plant is extensively equipped with a number of sensors and instrumentation devices for experimentation and data collection. The influence of the evaporative cooler on the energy saving potential and thermal comfort of the central cooling plant is evaluated. The advantages of this proposed hybrid system rests with the fact that the refrigeration effect of the chiller’s evaporator is decreased, which causes reduction of compressor power consumption. Results show that the hybrid system can provide average monthly energy savings between 11% and 24%, while enhancing the comfort level inside the building. Practical application : With traditional heating, ventilation and air conditioning systems contributing to 40% of a building’s overall energy consumption, the public’s increasing reliance on them as a necessity rather than a luxury is an issue in urgent need of attention. This together with a growing demand for cost-effective infrastructure and appliances has necessitated new installations and major retrofits in occupied buildings to achieve energy efficiency and environmental sustainability. The aim of this paper is to present a new integrated heating, ventilation and air conditioning system to meet these requirements without compromising comfort and indoor air quality.
2011 IEEE/SICE International Symposium on System Integration (SII), 2011
Cooling systems in buildings are required to be more energy-efficient while maintaining the stand... more Cooling systems in buildings are required to be more energy-efficient while maintaining the standard air quality. The aim of this paper is to explore the potential of reducing the energy consumption of a central air-conditioned building taking into account comfort conditions. For this, we propose a new hybrid evaporative cooling system for HVAC efficiency improvement. The integrated system will be
ABSTRACT The purpose of this study is to develop an optimization methodology for the detailed ene... more ABSTRACT The purpose of this study is to develop an optimization methodology for the detailed energy and cost effective design of a finned-tube condenser coil in order to enhance the system performance. Using this method, the frontal area of the condenser coil is maintained as constant, while other geometrical parameters of the thermal and economic performance of the system are varied and investigated. An existing air-cooled direct expansion (DX) rooftop package unit of a real-world commercial building is used for experimental data collection. First, the theoretical–empirical model for the system components is developed. Based on mathematical models and using collected data, a numerical algorithm is developed and embedded in a transient simulation tool. The integrated simulation tool is then validated by using the wide range of operating data obtained experimentally from the cooling plant during summer time. Furthermore, a mixed heuristic–deterministic optimization algorithm was implemented to determine the synthesis and design variables that influence the cost and energy efficiency of each configuration. Different new designs for condenser coil were then constructed to evaluate the potential of design improvements. Afterwards, the computer model was used to predict how changes in condenser coil geometry would affect the cost and energy consumption of the system.
ABSTRACT Decreasing the energy consumption of heating, ventilation and air conditioning (HVAC) sy... more ABSTRACT Decreasing the energy consumption of heating, ventilation and air conditioning (HVAC) systems is becoming increasingly important due to rising cost of fossil fuels and environmental concerns. Therefore, finding novel ways to reduce energy consumption in buildings without compromising comfort and indoor air quality is an ongoing research challenge. One proven way of achieving energy efficiency in HVAC systems is to design systems that use novel configurations of existing system components. Each HVAC discipline has specific design requirements and each presents opportunities for energy savings. Energy efficient HVAC systems can be created by re-configuring traditional systems to make more strategic use of existing system parts. Recent research has demonstrated that a combination of existing air conditioning technologies can offer effective solutions for energy conservation and thermal comfort. This paper investigates and reviews the different technologies and approaches, and demonstrates their ability to improve the performance of HVAC systems in order to reduce energy consumption. For each strategy, a brief description is first presented and then by reviewing the previous studies, the influence of that method on the HVAC energy saving is investigated. Finally, a comparison study between these approaches is carried out.
The purpose of this study is to develop an optimization methodology for the detailed energy and c... more The purpose of this study is to develop an optimization methodology for the detailed energy and costeffective design of a finned-tube condenser coil in order to enhance the system performance. Usingthis method, the frontal area of the condenser coil is maintained as constant, while other geometricalparameters of the thermal and economic performance of the system are varied and investigated. Anexisting air-cooled direct expansion (DX) rooftop package unit of a real-world commercial building isused for experimental data collection. First, the theoretical–empirical model for the system componentsis developed. Based on mathematical models and using collected data, a numerical algorithm is devel-oped and embedded in a transient simulation tool. The integrated simulation tool is then validated byusing the wide range of operating data obtained experimentally from the cooling plant during sum-mer time. Furthermore, a mixed heuristic–deterministic optimization algorithm was implemented todet...
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