Henry Nasution

Energy savings in air conditioning system using ejector: An overview

There are two ejector configurations described in the present study: ejector refrigeration cycle and the ejector as an expansion device. The use of waste heat from the car engine and industry as a heat-driven energy for air conditioning system in automobile and building can save energy. Although the ejector refrigeration cycle has a low COP, the use of waste heat as a heat-driven energy incurs a lower operational cost compared with vapor compression refrigeration system. In addition, an ejector as an expansion device can be applied in the vapor compression refrigeration cycle to improve the performance system.

Numerical Study of Ejector as an Expansion Device in Split-Type Air Conditioner

This paper presents a numerical approach for determining the motive nozzle and constant-area of an ejector as an expansion device, based on cooling capacity of the split-type air conditioner using R22 as working fluid. The use of an ejector as an expansion device in split-type air conditioner can enhance the coefficient of performance (COP) system. Typically, the split-type air conditioner may be installed on the geographical area with moderate or high outdoor air temperature using capillary tube. For this reason, the motive nozzle and constant-area diameters of the ejector must be designed according to these conditions. The diameters of the ejector are crucial in improving the COP. The results showed that the motive nozzle diameter is constant (1.14 mm) with variations of the condenser temperature, whereas the constant-area diameter decreases as the condenser temperature increases.

Energy Analysis of Split Air Conditioning System Using Variable Speed Drive

An air conditioning (AC) system design requires two main aspects that should be taken into consideration, there are reducing energy consumption and ensuring thermal comfort. This paper present variable speed drive on compressor motor is being tested to reduce the energy consumption. Conventional AC system to use on/off controller where the compressor motor turns itself on and runs at maximum speed then turns back off to achieve the temperature setting. This controller consumes more energy, however, by using a variable speed drive, the compressor motor will constantly run at various speeds while achieving the temperature setting. A system that developed software to implement the controller algorithms was installed in a thermal environmental room with data acquisition to monitor the room temperature, energy consumption, energy saving and coefficient of performance. Measurements were taken during the one hour experimental period at a time interval of three minutes for temperature set-points of 22, 23 and 24°C with internal heat loads of 500, 700 and 1000 W. The proposed technique can save energy and thermal comfort in comparison with conventional on/off control. The experiment results indicate that the application of variable speed drive on compressor motor is better than conventional on/off.

Thermodynamic Analysis of Ejector as an Expansion Device on Split-Type Air Conditioner Using R410A as Working Fluid

Typically the split-type air conditioner uses a capillary tube as expansion device. To enhance the performance of the system, an ejector can be applied as expansion device to replace capillary tube. Based on the numerical modeling, the coefficient of performance (COP) of standard cycle using R410A as working fluid was slightly lower than that of R22. The use of an ejector as an expansion device on a split-type air conditioner using R410 increased the COP by 10.8%. Also, R410A has a lower total GWP impact compared with R22, which reduce negative impact on the environment.

Retrofitting R-22 split type air conditioning with hydrocarbon (HCR-22) refrigerant

An experimental study to evaluate the energy consumption of a split type air conditioning is presented. The compressor works with the fluids R-22 and HCR-22 and has been tested varying the internal heat load 0, 500, 700 and 1000 W. The measurements taken during the one hour experimental periods at 10-minutes interval times for temperature setpoint of 20oC. The performance data considered where the evaporator cooling load, the condenser heat rejection, the electrical energy consumption, the refrigeration system temperatures, and the room temperature. And hence the Coefficient of Performance (COP) could be determined. The final results of this study show an overall better energy consumption of the HFC-22 compared with the R-22.

Investigation of Various Mixtures of HC290/HC600 Refrigerants in Adiabatic Capillary Tube Used in Split-Type Air-Conditioner

: According to Montreal Protocol, HCFC22 (hydro chlorofluorocarbon), a commonly used refrigerant in domestic refrigeration and air-conditioner, must be phased out owing to its environmental problem. Several natural substances including ammonia, carbon dioxide, water and hydrocarbon (HC) such as propane (HC290) and butane (HC600) and their mixtures have immerged as close substitute. Literature showed that pure HC refrigerant may not be suitable enough because of the difference in operating pressure and volumetric cooling capacity when compared with HCFC22. The main objective of this study is to theoretically investigate different ratios of HC refrigerants HC290/HC600 mixtures flowing through adiabatic capillary tube using homogenous model. In this study, the percentage by volume of HC290 was varied from 30 to 40 % in a step of 5%. The pressure at the two extreme ends and temperature along the capillary tube, using HCFC22 refrigerant, which was used as benchmark, was experimentally determined in the air-conditioning (AC) system. Comparing the model results with the experimental data showed that HC refrigerants HC290/HC600 in ratio 35%/65% gave 2.95% minimum error and thus it can be used as a substitute to HCFC22 in the split-type AC system.

The application of gas ejector for road transport air conditioning system

The depletion of fossil fuel supply requires fuel and energy saving in energy utilization system. Therefore, these required the development of new and efficient technologies as to reduce fuel consumption especially in air conditioning of road vehicles. Currently, the air conditioning for road vehicles uses vapor compression system. Although the vapor compression system has high COP, the compressor is driven by vehicle engines, which take additional fuel consumption when the air conditioning system is in operation. In this study, the waste heat of radiator drives the ejector refrigeration for air conditioning. Although the ejector refrigeration system has low COP, the use of heat driven air conditioning will reduce the fuel consumption as compared with conventional system. This is because the systems do not use the mechanical engine load. The analysis of this study is based on the ejector refrigeration system using natural refrigerant (isobutene). The evaporation temperature is 10°C, condensation temperature is 35°C, generator temperature is 90°C with ejector isentropic efficiency of 0.7, and the COP system is 0.25. The heat released by the radiator of typical small road vehicles is between 60 to 100 kW and if the generator absorbs 20% of the heat, the heat contained in the generator is 12 to 20 kW. When the ejector air conditioning system has a COP 0.25, it will generate cooling capacity between 3 to 5 kW, compared with the conventional air conditioning of similar vehicles, which is approximately 2 to 4.4 kW.

Experimental evaluation of automotive air-conditioning using HFC-134a and HC-134a

An experimental study to evaluate the energy consumption of an automotive air conditioning is presented. In this study, these refrigerants will be tested using the experimental rig which simulated the actual cars as a cabin complete with a cooling system component of the actual car that is as the blower, evaporator, condenser, radiators, electric motor, which acts as a vehicle engine, and then the electric motor will operate the compressor using a belt and pulley system, as well as to the alternator will recharge the battery. The compressor working with the fluids HFC-134a and HC-134a and has been tested varying the speed in the range 1000, 1500, 2000 and 2500 rpm. The measurements taken during the one hour experimental periods at 2-minutes interval times for temperature setpoint of 20°C with internal heat loads 0, 500, 700 and 1000 W. The final results of this study show an overall better energy consumption of the HFC-134a compared with the HC-134a.

Performance study of DC compressor for automotive air conditioning system

The automotive air conditioning compressor (AAC) is belt-driven by the engine. The compressor speed is directly proportional to the engine speed. Therefore, the cooling capacity will vary as the engine speed changes. To meet the air conditioning (AC) demand, the compressor continually cycles on and off. In the research, the compressor of the AAC is driven by an electric motor which in turn is operated by electrical battery (12 volt). The use of direct current compressor (DCC) is seen as a solution of the existing system. Using the proposed system, DCC gets significant improvements in energy efficiency. Compared with AAC system, the energy conservation effect is about 77.5% to 86.35%.

Modeling and Parametric Study of Cooling Loads Characteristics for Automotive Air-Conditioning System

This paper presents a steady-state modeling and parametric study on the characteristics of cooling loads for an automotive air-conditioning system. The model enables the hourly prediction of vehicular cabin cooling load profile at various operating conditions and types of vehicle. The model utilizes correlations and equations proposed by ASHRAE and previous researchers available in the open literature. A validation exercise indicates that the simulation results are within 5% of published results. In the parametric study, the effects of five parameters: vehicle surface color, number of passenger, cabin temperature, vehicle speed and angle of front wind screen on the hourly cooling load profile on a daily basis are investigated. It was found that an increase in number of passenger and vehicle speed, darker vehicle surface color and lower cabin temperature will increase the cooling load. Meanwhile, the angle of front wind screen does not significantly influence the cooling load profile. In conclusion, the cooling loads profile can be used for air-conditioning system improvement/optimization exercise. The generic model can be used for complete vehicle air-conditioning simulation program towards energy-efficient air-conditioning system for better overall performance, especially in the early stage of vehicle development.