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This article presents an investigation on the effects of using ventilation fans on the air temperature inside a car passenger compartment when the car is parked under the sun. It was found from a measurement that the air temperature inside the passenger compartment could raise up to 48°C. Computational fluid dynamics method was used to develop model of the compartment and carry out flow simulations to predict the air temperature distribution at 1 pm for two conditions: without ventilation fans and with ventilation fans. The effects of fan location, number of fans used and fan airflow velocity were examined. Results of flow simulations show that a 17% temperature reduction was achieved when two ventilation fans with airflow velocity of 2.84 m/s were placed at the rear deck. When three fans were used, an additional 3.4% temperature reduction was attained. Placing two ventilation fans at the middle of the roof also reduced the air temperature by 17%. When four fans were used a further 4.8% temperature reduction was achieved. Increasing the airflow velocity at the four fans placed at the roof, from 2.84 m/s to 15.67 m/s, caused only a small reduction in the air temperature inside the passenger compartment

There has been an increasing demand for renewable energy in order to create a sustainable society as the non-renewable energies such as fossil fuel resources are limited. Modern wind turbines claim that they have a high efficiency in term of wind energy extraction. However, there are still having losses due to tip vortex causing to a reduction in performance. Motivated by this reason, this research aims at exploring the possibility to increase the performance of low speed small-scaled horizontal axis wind turbine with various tip devices using Computational Fluid Dynamics (CFD). Four wind turbine blades with different tip devices which consist of sword tip, swept tip, upwind winglet and downwind winglet are compared with wind turbine blade without tip device in term of CP. The application of tip device can significantly reduce induced tip vortex and improve wind turbine performance. For TSR below than 4, adding a sword tip increases CP about 7.3%, swept tip increases CP about 9.1%, upwind winglet increases CP about 1.8% and downwind winglet increases CP about 3.2%. It is observed that the best tip device for low wind speed application is swept tip as it give the highest performance increment compared to without tip device.

The presence of moisture in the air along with temperature has a long term and devastating effect on man and material. One way to create a low humidity environment is by using a solid desiccant wheel system. In the present work, an experimental analysis has been carried out under steady-state conditions to investigate the effects of different operating parameters on a solid desiccant wheel system performances. An experimental rig consists of an FFB300 air dehumidifier system was constructed. A parametric investigation was carried out to examine the effects of the reactivation air inlet temperature and process air outlet velocity on the thermal effectiveness, dehumidification efficiency, and moisture removal rate of the desiccant wheel system. The analysis shows that both thermal effectiveness and dehumidification efficiency decrease with the increase of the reactivation air inlet temperature, by 2.5 % and 43 %, respectively. Likewise, when the process air outlet velocity increases both performances criteria reduce by 10 % and 28 %, respectively. The moisture removal rate increases significantly by 30 % as the reactivation air inlet temperature increases. However, the process air outlet velocity has no significant effect on the moisture removal rate.

A combined natural ventilation and mechanical fans are commonly used to cool the interior space inside the mosques in Malaysia. This article presents a study on thermal comfort in the Al-Jawahir Mosque, located in Johor Bahru, Malaysia. The objective is to assess the thermal comfort inside the mosque under the present ventilation system by determining the Predicted Mean Vote (PMV) and the Predicted Percentage of Dissatisfied (PPD). These values were then compared to the limits stated in the ASHRAE Standard-55. It was found that the PMV varies from 1.68 to 2.26 while the PPD varies from 61% to 87%. These show that the condition inside the mosque is quite warm. Computational fluid dynamics (CFD) method was used to carry out flow simulations, to identify a suitable strategy to improve the thermal comfort inside the mosque. Results of CFD simulations show that installing four exhaust fans above the windows on the west-side wall of the mosque is the most effective strategy to improve the thermal comfort inside the mosque. Both the PMV and PPD values can potentially be reduced by more than 60%.

Passengers commuting with buses are exposed to indoor air that contains contaminants such as particulate matters (PM). These contaminants could affect the passenger’s health in long and short term durations. Depending on the size of the particles, a respiratory allergy and airborne transmission could affect the passenger’s health. This article presents a field measurement to assess the airborne particles concentration of particulate matters inside a passenger bus compartment. The data collections were done at the front, middle and rear sections of the compartment, at a height of 1.1 m from the floor. The field measurements were carried outfrom 7.30 AM to 9.00 AM, 1.30 PM to 2.30 PM and from 4.15 PM to 5.00 PMwhich are the peak hours periods. A HPC300 handheld particles counter was used to measure the concentrations of PM1, PM2.5 and PM10. The results show that the concentrations of PM1, PM2.5 and PM10 were significantly high during the afternoon and evening hours. Also, the concentrations of PM1, PM2.5 and PM10 were higher at the front section of the passenger compartment compared to the middle and rear sections. It was also found that the peak hour periods, ventilation setting, infiltration, boarding and unboarding of passengers are among the factor that would increase the concentrations of PM1, PM2.5 and PM10 particles inside the passenger compartment.

A bus compartment requires a good ventilation system to provide sufficient fresh air and a uniform air flow to passengers. This article presents a numerical study using CFD method to investigate the effects of using different ventilation setups on the air flow velocity and temperature distributions inside a passenger bus. Fluent software was used to develop a simplified three-dimensional model of a quarter section of a bus passenger compartment. Turbulent flow simulation was carried out based on a standard k-epsilon model to predict the distributions of air temperature and velocity inside the passenger compartment. The effects of two ventilation setups, namely mixing and displacement ventilations on the air temperature and air flow velocity distribution were also examined. Results of CFD simulations show that the displacement ventilation setup results in more uniform distribution of air flow velocity and air temperature inside the bus passenger compartment.

In a hospital operating room, adequate air flow and cleanliness are crucial to protect the patient from surgical site infection (SSI) during a procedure. The probability of the patient to get the infection is related to the concentration of bacteria carrying particles inside the room. This paper presents a field measurement study to quantify the concentration of particulate matters (PM) in a hospital operating room which complies with the ISO Class 7 requirements. The operating room was equipped with High Efficiency Particulate Air (HEPA) filters and a vertical laminar air flow (LAF) system. The measurements were conducted at three height levels from the floor namely 1.2 m, 1.8 m and 2.4 m. The data was logged at a rest condition, in accordance to the ISO 14644-1 requirements. A HPC300 particle counter was used to measure the concentrations of particulate matters namely PM0.5, PM1 and PM5. The results show that the concentrations of all particulate matters were higher at the height level of 1.2 m compared to other height levels. The concentration of PM0.5 was relatively higher than PM1 and PM5 in the vicinity of operating table.

This article presents a study to estimate the potential saving in annual operating cost of a hypothetical greenhouse used for planting strawberry, in Johor Bahru, Malaysia. The greenhouse needs to be maintained at a constant temperature of 20°C at all time. The goal of this study is to select a suitable TES system that can save the annual cost of electricity usage to meet the cooling load requirement of the greenhouse, based on a 24 hours operating duration and local electricity tariff. Comparison is made with the annual cost for running a conventional air-conditioning (AC) system to meet the cooling requirement. The cooling load requirement of the greenhouse dictates the capacity and size of the potential TES systems, which was estimated based on the highest total annual cooling load. Three TES system operating arrangements were considered in this study: TES full storage combined with AC systems, TES full storage and TES partial storage. Among these three arrangements, the TES full storage was found to have the highest an annual cost saving of about RM 58,990 compared to the cost of using the conventional AC system alone. This represents about 68 % of annual operating cost saving, which is considered very significant.

Air distribution systems inside a bus compartment are important for providing healthy and comfortable environment for passengers. Lack of ventilation inside the bus passenger compartment causes an increase level of air contaminants concentration. Particulate matters and carbon monoxide are indoor air contaminants which can affect the passenger’s health such as respiratory problem and lung cancer. This article reports the results of a CFD simulation on transport of carbon monoxide and particulate matter 1 inside a passenger compartment of a university’s shuttle bus. Fluent CFD software was used to develop a simplified three-dimensional model of the bus passenger compartment. Flow analysis was carried out using RNG k-e turbulent model for air flow, discrete phase and species transport for the air contaminants. Four variations of ventilation system namely two mixing ventilation types, combined mixing with displacement ventilation and combined mixing ventilation with underfloor air distribution was examined. The CFD simulation results show that the use of the combined mixing and displacement ventilation and also the combined mixing and underfloor ventilation types are capable of reducing the concentration of carbon monoxide and particulate matter 1 inside the bus passenger compartment by 81% and 54%, respectively.

Analisis haba di dalam struktur pandu gelombang optik telah dijalankan untuk mengkaji taburan suhu keratan rentas apabila dipanaskan dengan elemen pemanas. Persamaan umum haba diprogramkan menggunakan kaedah berangka pembezaan terhingga. Perbezaan keputusan yang ketara telah diperoleh apabila nilai keberaliran haba yang berbeza bagi setiap elemen pandu gelombang dan mekanisma konveksi ke persekitaran dipertimbangkan. Kata kunci: Kesan termo–optik, analisis terma, kaedah pembezaan terhingga A thermal analysis in optical waveguides structure is simulated in order to predict the temperature distribution over the waveguide cross–section, when heated by a heating element. A steady state heat equation is solved by using finite difference numerical method. It is observed that by applying different value of thermal conductivities for each waveguide element and further application of convection mechanism to the ambient, obvious differences with other researchers’ work are recorded. Key words: Thermo–optic effect, thermal analysis, finite difference method