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Noise pollution is a workplace hazard which causes loss of hearing, depending on the sound pressure level and duration of exposure. Because duration of exposure is usually uncontrollable, sound absorbers are used to reduce the value of sound pressure level. A common method to reduce noise is to use porous sound absorbers made out of mineral wools or glass fibres. However, these materials pose health risks and are non-recyclable. This project aimed to fabricate a sound absorber using recycled paper which is in the form of egg cartons as an alternative to the abovementioned fibres. Paper fibres posses high fibre porosity and can be manufactured in a manner which the properties can be easily controlled, making them ideal to be made into sound absorbers. Furthermore, they are biodegradable, do not pose health risks and can be manufactured into different shapes easily. Recycled paper was first turned into pulp, blended and poured into moulds. Different amounts of pulp was compressed until the sample size was approximately 20 mm thick and then dried in a furnace dryer at 600C for 12 hours. The samples were tested using a two-microphone, transfer function impedance tubes according to the ISO 10534-2 standard. Its porosity was determined using a modified wash basin method. The results indicate that the optimum panel has an average noise reduction coefficient, (NRC) of 0.50, which qualifies it to be used as a sound absorbing material. It also encounters its maximum value of 0.98 which occurred at the 1575-1675 Hz range. When compared to other materials, recycled paper has similar properties as coir fibre and is quite comparable to other commercial sound absorbers at the same thickness.

Thermoelectric cogeneration may be applied to the exhaust of an automobile to generate additional electric power, by applying a temperature differential across the thermoelectric power generation modules. To obtain maximum net power, the highest allowable temperature difference should be obtained. Therefore, a cooling system should be employed to ensure that the cold side of the thermoelectric modules remain as cold as possible. An evaporative cooling system patented by Einstein and Szilard is used as a base for a non-parasitic cooling system to be used together with thermoelectric modules. The cooling system utilizes the same heat which powers the thermoelectric modules as a power source. By utilizing the high solubility of ammonia in water, the solubility dependency with temperature, and usage of polar and non-polar solvents to direct the flow of ammonia as a coolant, it is possible to create a cooling system which performs better than passive heat sinks, but negates the power requirements of active cooling systems.

Thermoelectric modules are a useful way to extract waste energy from a readily available low quality heat source. However, the voltage generated by these modules varies with the temperature difference across its surfaces which are prone to fluctuations. Furthermore, the amount of voltage generated by individual modules is low. This can be rectified using voltage converters to stabilise the output voltage at the expense of some efficiency. In the case where a minimal number of modules are being used, a boost converter can be used to increase the input voltage from the thermoelectric modules to a higher level. Our previous study showed the results of the boost conversion process for multiple temperature differences, resulting in multiple input voltages and currents and found that the conversion efficiency increases with increasing input voltage at an almost constant input current. In this paper, we compare the experimental results for conversion efficiency against the expected values provided by the manufacturer, and find that when the input voltage is closer to the desired output voltage, the conversion efficiency increases.