Abstract: This paper focuses on the monitoring of indoor air quality parameters, namely: indoor temperature, humidity, velocity, particulate matter, carbon monoxide and carbon dioxide in day care centres. This study selected 15 day care centres located in Kuala Lumpur, Malaysia. These day care centres were categorized as follows: (1) day care centers near an industrial area, (2) day care centers near a main road, and (3) day care centers in a residential area. The obtained data showed that the values for the indoor air quality parameters in all day care centres were still well below the recommended value according to the Department of Safety and Health, Malaysia. The day care centers near an industrial area had the highest value of carbon monoxide, and carbon dioxide as compared to the day care centers near a main road and the day care centers in a residential area. The average concentrations of carbon monoxide, and carbon dioxide in the day care centers near an industrial area were 3.67 ppm and 801.56 ppm respectively. Meanwhile, the carbon monoxide, and carbon dioxide in the day care centers near a main road area and the day care centers in a residential area were 3.13 ppm, 768.22 ppm, 2.92 ppm and 733.70 ppm, respectively.
Abstract: Sensible (temperature) and latent (moisture) loads are the common load an air-conditioning (AC) system need to handle. Both loads are generated from conditioned space, internal source and outdoor air ventilation. This study is to monitor the indoor air quality IAQ in hotel restaurant and the results are compared with Malaysian standard MS1525 and Industry Code of Practice (COP) on IAQ 2010, Department of Safety and Health (DOSH) Malaysia. The AC system performance was also monitored to identify the actual cooling energy usage base on standard operations. Psychrometric chart was used to analyse the actual cooling energy required and identified the latent and sensible loads significantly. The result of the study shows the mean air temperature, relative humidity (RH), carbon dioxide (CO) and carbon monoxide (CO2) levels were within range as stipulated by standard and code of practice. Heat loads analysis on a psychrometric chart showed the total cooling energy as 296.2 kW; of which 196.3 kW was contributed to primary air unit (PAU) and 99.9 kW to air handling unit (AHU) respectively. The primary contribution for sensible and latent loads and recommendation of potential energy saving also been discussed to meet energy efficient in AC system while maintaining good indoor air quality in the restaurant.
Abstract: This paper presents the simulation of microwave heating by coupling high frequency electromagnetic with transient heat transfer using finite element method edge base of ANSYS software. Helmholtz equation of electric field has been formulated from Maxwell equations to predict electric field and the mathematical model of transient thermal analysis was included. Three cases have been examined numerically to investigate electric field, dissipated heat, temperature distribution and weight loss of soot at operation frequency 2.45 GHz. The simulation results showed that heat is generated from inside to outside of soot. The temperature at penetration depth increased till ignition point and after further heating, maximum temperature was attained, followed by temperature decreases due to mass transport. Maximum electric field was found to be located on the front face for the small samples with dimensions less than penetration depth. The predicted results have been compared with experimental results which show the validity of the simulation.
Abstract: This paper studies the current thermal comfort condition of an air-conditioned cafeteria based on objective measurements and computational fluid dynamics (CFD) modeling. Indoor comfort parameters such as temperature and airflow rate were simulated by a CFD tool. The results from field measurements and predicted values were then compared and contrasted. A simulated model that has the same geometrical configuration as the cafeteria was set as a benchmark model. Several additional models with different configuration of cafeteria layouts were proposed to achieve the required air temperature. It was found that the predicted results from the proposed models showed even distributions of airflow characteristics and temperature gradients. To maintain a thermally-acceptable air temperature of 28 °C, it is proposed that an additional air-conditioning unit be retrofitted to the current cafeteria layout.
Abstract: Using fluidic self-excited jets increases the rate of fluid mixing and reduces fuel consumption in industry burners (torches) and combustion chambers. The geometry of such jets is an important factor for fluidic jet determination. This study is concerned with investigating the types of fluidic nozzles configuration. The effect of nozzle configuration types was studied on various parameters such as frequency, velocity profile, velocity decay rate, the half angle of jet spread, and entrainment ratio. Maximum frequency and excited oscillation amplitude of fluidic jets were observed in the original geometry configuration. Also, the maximum spread rate and minimum velocity profile were observed in this geometry. Velocity decay rate shows its maximum magnitude in the original geometry configuration. Turbulence intensity reaches its maximum value in this geometry without any internal nozzle, whereas it shows the minimum value at geometry with an additional wall along the internal nozzle. The maximum increase in the half angle of jet spread was seen in the original geometry configuration. In this geometry, entrainment ratio is less than one, while in the geometry to create steady jets, entrainment ratio is more than one.
Abstract: This paper presents a study and investigation of an improvement of boiler efficiency with an automatic control of air quantity into a combustion chamber. A fire tube boiler with a fixed gate and screw conveyor for feeding fuel was used to test the automatic control system, and a sub-bituminous was used as a fuel for this study. The increase in boiler efficiency was based on controlling amount of air quantity for fuel combustion before entering to the combustion chamber using fuzzy logic control algorithm. Automatic combustion control was achieved by measuring the amount of Oxygen gas (O2) from flue gas stack. From the experimental results, it was indicated that the automatic control system can control the average amount of O2 in flue gas at 11.09% when the O2 in the flue gas was set at 10%. The boiler efficiency was increased by 4.34%, and the energy consumption was reduced to have a fuel saving of 195.88 ton/year.
Abstract: Researchers especially from engineering field are using Computer Fluid Dynamic (CFD) software to simulate the three dimension (3D) model before they perform any experiments to prove their theories. The aim of this study is to develop a valve model in 3D using Solidworks software and to analyze internal fluid flow using Solidworks Flow Simulation (SWF) software to prove that this software has the capability in performing fluid simulations for the ball valve. The SWF successfully calculates the value of outlet velocity for the ball valve at different closing angles and different pressures value. The results shown are significantly acceptable by referring to the outputs of practical experiment and simulation incidence’s error of Ozdamar model 2007. The average error in calculation for SWF is about 7.42%, unlike FLUENT which is around 11.09%. Therefore; the engineers can simulate their models with higher accuracy using SWF software.
Abstract: Wind catchers are structures used for natural ventilation using wind induced into buildings. Recently this has attracted attention for green buolding features There is limited studies on the different venturi shapes and their effects on inducing wind into buildingss.. This study considered three configurations ie. the shallow ellipse, the ellipse and the hemisphere in a wind tunnel with different speeds ranging from 8 m/s to 20 m/s. The negative pressure coefficient at the lower center of the roof is considered as the criteria for higher ventilation rate. The shallow ellipse performed the best but due to construction limitations other alternatives are recommended.
Abstract: The synthesis of heat exchanger network (HEN) is a comprehensive approach to optimize energy utilization in process industry. Recent developments in HEN synthesis (HENS) present several heuristic methods, such as Simulated Annealing (SA), Genetic Algorithm (GA), and Differential Evolution (DE). In this work, DE method for synthesis and optimization of HEN has been presented. Using DE combined with the concept of super-targeting, the optimization is determined. Then DE algorithm is employed to optimize the global cost function including the constraints, such as heat balance, the temperatures of process streams. A case study has been optimized using DE, generated structure of HEN and compared with networks obtained by other methods such as pinch technology or mathematical programming. Through the result, the proposed method has been illustrated that DE is able to apply in HEN optimization, with 16.7% increase in capital cost and 56.4%, 18.9% decrease in energy, global costs respectively.
Abstract: The paper presents a study on performance of improvement carried out on a tubular ice making machine by reducing feed water temperature using a shell and tube heat exchanger. An ice making machine with a capacity of 20 ton per day was used to in this study. The shell and tube heat exchanger was designed to reduce the feed water temperature. It has a length of 1.5 meters and 3.5 m2 of heat transfer area. The heat exchanger were installed at the inlet of an evaporator. Then, the performance and energy consumption of the ice making machine were examined with the experimental condition of cooling temperature at 20°C and 30°C. The comparison of the performance and energy consumption before and after heat exchanger installation were also studied. From the experiment, the results showed that the heat exchanger can reduce the feed water temperature by an average of 7.5°C, and the energy consumption was decreased by 17.1 %. The cycle time for ice production was decreased to 7 minute/cycle, and the capacity of the ice making machine was increased by 17.5%. If the cost of running the heat exchanger is 200,000 baht, this solution can potentially save the energy expense of up to 269,570 baht/year with a payback period of 0.93 year.