28 research outputs found
Performance analysis of air conditioning system and airflow simulation in an operating theater
No full textNumerical Simulation of a Two-bed Solar-driven Adsorption Chiller in a Tropical Climate
Get PDFCooling systems in tropical countries consume a
large part of energy usage in a building, especially in a tropical climate,
which places a high demand on cooling systems throughout the year. This paper
presents a simulation of a two-bed silica gel-water adsorption chiller,
utilizing solar energy based in the tropical climate of Indonesia. The
adsorption chiller is being mathematically modelled and calculated numerically
using MATLAB®. The simulation is used to show the performance of the chiller
during the working hours, based on maximum and minimum inputs of solar
irradiation in Indonesia Furthermore, mass recovery and heat recovery is also
applied in the adsorption cycle in order to increase the cooling capacity. The
adsorption chiller is based on the most recent chiller developed by Shanghai
Jiao Tong University (SJTU). The simulation results generally demonstrated the
running characteristics of the chiller under a range of different values of
solar radiation. Furthermore, the simulation results in detail showed that
during the maximum value of irradiation, the average value of COP can reach
0.26, while during the minimum value of irradiation the COP is 0.15. At the
same time, the cooling capacity is also varied which can reach up to the
maximum value of 37.8 kW, whereas in the minimum range of irradiation values,
the cooling capacity dropped to 5.3 kW
Characteristics of evacuated tubular solar thermal collector as input energy for cooling system at Universitas Indonesia
No full textAnalysis of convergent and divergent-convergent nozzle of waterjet propulsion by CFD simulation
No full textAn experimental investigation on mass effect of hydrocarbon refrigerant (R600a) on household refrigerator energy consumption
No full textEffect of regeneration air temperature on desiccant wheel performance
Get PDFDesiccant wheels are used as an air dehumidifier in air-conditioning and industrial applications. Desiccant wheel performance determines the size and cost of the whole system. A good desiccant wheel is one that saves energy usage. This article presents an experimental investigation on the effects of varying the regeneration air temperature, viz., 50, 60 and 70°C, on desiccant wheel performance. Three performance criteria were considered, namely condition of process outlet air, dehumidifier efficiencies and dehumidification rate. Two kinds of efficiency of the desiccant wheel dehumidifier were examined, namely thermal and dehumidification efficiency. Results of the experiments show that increasing the regeneration air temperature increases the dry bulb temperature of the process outlet air. However the moisture content of the process outlet air is reduced. The dehumidification efficiency of the desiccant wheel decreases with increasing regeneration air temperature, i.e., 46.7, 45.8 and 45.3 % for 50, 60 and 70°C, respectively. In contrast, the dehumidification rate increases with an increase in the regeneration air temperature, namely 32.6, 37.1 and 40.2 g/h for 50, 60 and 70°C, respectively
High Pressure Adsorption Isotherm of CO2 on Activated Carbon using Volumetric Method
Get PDFHigh Pressure Adsorption Isotherm of CO2 on Activated Carbon using Volumetric Method. Adsorption system is ones of the most effective methods for CO2 separating with other substances that produced from the burning of fossil fuels. In the design for that application, beside of characteristics of porous material (adsorbent) data, CO2 adsorption data on the adsorbent (kinetic and thermodynamic) are also needed. The aim of this research is resulting isothermal adsorption data at pressures up to 3.5 MPa by indirect methods (volumetric method) at isothermal temperature of 300, 308, 318 and 338 K. Adsorbent that used in this research is activated carbon made from East of Kalimantan coals by physical activation method (CO2) which is the surface area of activated carbon is 668 m2/g and pore volume is 0.47 mL/g. Carbon dioxide (CO2) that used in this research is high purity carbon dioxide with a purity of 99.9%. Data from the experiment results then correlated using the Langmuir and Toth equations model. The results showed that the maximum adsorption capacity is 0.314 kg/kg at 300 K and 3384.69 kPa. The results of regression of experiment data using Langmuir and Toth models were 3.4% and 1.7%
Control Strategy of Solar Thermal Cooling System under the Indonesia Climate
No full textSolar thermal cooling system was installed on Mechanical Research Center (MRC) Building that is located in Universitas Indonesia, Depok, Indonesia. It is the first cooling system in Indonesia that utilizes solar energy as energy input combined with natural gas; therefore, the control system must be appropriated with the climates. In order to stabilize the cooling capacity and also to maximize the use of solar energy, the system applies some controllers. Constant flow rate and on/off controller are applied for the hot water, chilled water and cooling water pumps. The hot water circulated by pump when the solar radiation is over than 400W/m2, and the chilled water is continually circulated by pump and its temperature is kept constant 7 °C by absorption chiller. The cooling water is also continually circulated until the outlet temperature of cooling tower below than 27 oC. Furthermore, the three-way valve is used to control the hot water for generate vapor on absorption chiller. The system performance using that control system is shown in this study results
Design and construction of temperature measurement in psychrometric chamber for split air conditioner testing and energy labelling
No full textA study on temperature, relative humidity, and energy consumption in long-distance trains air conditioning systems in Indonesia
No full textTrains are efficient and cost-effective means of public transportation capable of carrying large groups of passengers. The Heating, Ventilation, and Air Conditioning (HVAC) system, a significant component with substantial energy usage in train operations, often encounters issues due to problems with the HVAC system failing to provide comfortable air quality, ultimately impacting passenger satisfaction and posing concerns for operators. A significant disparity in understanding of HVAC systems on Indonesian trains is frequently observed in tropical regions, where ensuring good air quality, stable temperatures, and controlled relative humidity levels over extended periods poses unique challenges due to the typically hot and humid climate characterized by high external temperatures and fluctuating humidity levels. Therefore, this study aimed to evaluate the ability of HVAC systems to maintain temperature and humidity in trains. Temperature and humidity were measured during the journey at various areas in passenger compartments in three executive class intercity trains, covering both day and night conditions. The results showed that maintaining a consistent level of thermal comfort parameters throughout the journey was challenging for HVAC systems. Data suggests that temperature fluctuations took place during the daytime, whereas relative humidity (R.H) levels in the night and early morning rose to 28.2 °C and 81.2 % respectively, surpassing the established standards ISO 19659–2 of 27 °C for temperature and 65 % percent for relative humidity. These results were expected to guide the improvement of future HVAC systems designs, enhancing their ability to maintain consistent temperature under varying conditions. Additionally, the designs would focus on better humidity control through the incorporation of a reheating process in air supply, ensuring consistency of long-distance journey
