Mohammad Zulfikar Ishak

Effect of heater geometry on the high temperature distribution on a MEMS micro-hotplate

Temperature uniformity on a micro-hotplate is important for gas sensor sensitivity, linearity, and resolution. There are several ways to create a uniform temperature distribution on a micro-hotplate. In this paper, the modification of microheater geometry is the method used. Four different heater geometries are simulated using ConvetorWare software to determine which geometry can give the most uniform temperature distribution. The simulations show that the heater geometry which combines parallel and meander shapes results in the most uniform heat distribution. The electrical potential and current distributions of the four different micro-heater geometries are also evaluated.

Study on temperature uniformity of thermal spreader integration with microcombustor for thermoelectric power generator

The effect of material, thickness and the magnitude of heat generated by microcombustor on heat distribution along thermal spreader for thermoelectric power generator are investigated. Impact of various materials and physical properties was studied upon sample 3 cm × 3 cm. The effect of thermal conductivity, specific heat capacity and thickness towards temperature uniformity of thermal spreader is observed. The result provides temperature profile of the thermal spreader dependencies of the source of heat. Results show that copper is the best thermal spreader material for thermoelectric power generator.

Effect of working fluid, acceleration and heater power on temperature profile inside a thermal convective accelerometer

Convective accelerometer does not contain seismic mass and work based on free convection heat transfer of electrical heater inside a hermetic chamber. Its sensitivity is dependent to the temperature distribution of working fluid inside the hermetic chamber. In this paper, the effect of working fluid properties, acceleration and heater power on temperature profile inside the convective accelerometer hermetic chamber is presented. Convective accelerometers with various working fluids (air, carbon dioxide, water, nitrogen, argon, helium, and ethylene glycol), heater powers (0.1 to 1.0 watts), and accelerations (1 to 5 g) were simulated by using ConventorWare 2010 software. Result shows, without acceleration the temperature profile of working fluid is symmetry around the vertical axis in relation to the heat source while with acceleration, the temperature profile is slightly skewed towards the acceleration direction. Argon is the best candidate for working fluid because it produces the largest temperature difference between the left and the right sides of the heater which would result in high sensitivity accelerometer. Convective accelerometer sensitivity also can be enhanced by increasing heater power, using gas-phase working fluids and locating the temperature sensors in the range between 100 to 300 μm away from the heater.

Deployment of wireless sensor network at Titi Serong Paddy field Crop, Malaysia

This paper presents the deployment wireless sensor network for paddy field crop application. The system can monitor pH level and water level in the paddy field crop. The calibration and system design of the sensor nodes were discussed. The sensor nodes installed at the Titi Serong Paddy field Crop, Malaysia. The system uses wireless data transmission to enable farmers to monitor continuously the water level and pH level at home without constant visits to the paddy field. This system can significantly reduce farmer workload while increasing crop yield.

Integrated Thermoelectric Power Generator - Wireless Sensor Node for Remote Area Application

The performance of a thermoelectric power generator for powering wireless sensor node has been studied and evaluated. This study covers the results obtained from two configurations of thermoelectric cell with heat source temperatures range from 40 to 230 °C. It was found that the highest output voltage is 9.08 V belong to configuration B with two parallel thermoelectric cells. This configuration was capable to power up sensor node compared to configuration A with the lowest heat source temperature at about 200 °C. To enhance the capability of the configurations, DC boost converter circuit has been developed and tested. By connecting to the DC boost converter, configuration A can power up the wireless sensor node with heat source temperature at about 220 °C while the minimum heat source temperature for configuration B was reduced from 200 to 170 °C. This study identified the optimum operation condition to power up wireless sensor node by thermoelectric power generator for remote application and make conclusion as to how to increase the performance of thermoelectric power generator by introducing DC boost converter.

Characterization of micro-cyclone combustion for micropower generator

This paper presents the characterization of a micro-cyclone combustor that burns liquefied petroleum gas. The combustor is made of stainless steel and has a reaction chamber volume of 1.15 cm3. Fuel and air are mixed inside the chamber by injecting the fuel perpendicularly to the tangentially injected air. The experiment demonstrates that the flame is sustained inside the micro-combustor over a wide range of fuel flow rates and equivalent ratios. The shapes of the flame are visualized experimentally, and the results indicate that different equivalent ratios produce different flame shapes. Combustion stability measurement exhibits that combustion blowout limit decreases as fuel flow rate increases from 10 sccm to 100 sccm, Wall temperature measurement shows that an equivalent ratio of 1.0 produces the most uniform temperature distribution.

Characterization of wet impregnation method for catalytic microcombustor using palladium

The wet impregnation method for catalytic micro-combustor was characterized by using palladium as a catalyst. The main purpose of this study is to increase the surface porosity of the catalyst support. A high surface porosity indicates that a high amount of catalyst was deposited within the surface areas. The performance of the catalytic micro-combustor improves with increasing catalytic surface area. The stainless steel catalyst support was treated with sulfuric acid solution containing polyvinyl (1.19 wt%) and propargyl alcohol (0.98 wt%). Combustion test was performed using LPG-air to test the performance of the catalyst. The surface support treated with polyvinyl (PVA) showed a higher surface porosity and combustion blow-out limit compared with propargyl alcohol. The combustion mode changes from surface to submerged combustion after the catalyst was deposited in the support surface.

Review of papers on the architecture and operation of microthermophotovoltaic system for MEMS power generation

Microthermophotovoltaic (micro-TPV) systems are generators currently being extensively developed to convert radiation heat energy from hydrocarbon fuel combustion into useful electricity by using low band-gap photovoltaic cell for microelectromechanical systems (MEMS). Micro-TPV systems consist of a heat source (microcombustor), a thermal emitter (microcombustor surfaces), a dielectric/optical filter, and photovoltaic cells. The architecture of a micro-TPV system and its components are currently the focus of research aiming to improve the overall system architecture, efficiency, and performance for practical implementation in the MEMS industry.