Feasibility study of an ice slurry-cooling coil for HVAC and R systems in a tropical building

The study applies the software Transient Systems Simulation Program (TRNSYS) to estimate the air conditions as well as the energy consumption of a typical library located in a tropical climate country. The simulation uses Typical Meteorological Year (TMY) weather data for Kuala Lumpur as the research site, which is the Dentistry library in University of Malaya is located in Kuala Lumpur. The current HVAC and R systems of the library are found to be inherently energy-inefficient and potentially improvable with an ice slurry-cooling coil. The impact on energy consumption and space thermal comfort of a custom-built AHU with an ice slurry-cooling coil incorporated in the HVAC and R systems is simulated in comparison to the baseline system.     

An experimental investigation into the CO2 gasification of deactivated activated-carbon catalyst used for methane decomposition to produce hydrogen

A series of experiments was conducted to study the CO₂ gasification of a deactivated palm-shell-based activated-carbon (ACPS) catalyst used for the thermocatalytic decomposition of methane to produce hydrogen. This catalyst becomes deactivated due to the accumulation of carbon deposits during the methane-decomposition process. The CO₂ gasification was carried out at 850, 900, 950 or 1000 °C to study the deactivated ACPS, which was used at methane-decomposition temperatures of 850 or 950 °C. A series of six methane-decomposition cycles at 950 °C alternating with five gasification cycles using CO₂ at 900, 950 and 1000 °C was also carried out to evaluate the stability of the catalyst. The experiments were conducted using a thermobalance by monitoring the change in mass of the catalyst with time, i.e., the mass gain during methane decomposition or the mass loss during CO₂ gasification. Gasification of the virgin and deactivated ACPS showed strong temperature dependence, with the half and complete gasification times having an exponential dependence on temperature. The gasification reactivity at different conversions was higher for the virgin ACPS and increased with increases in the decomposition temperatures used for deactivation of the ACPS. The activation energies of virgin ACPS and ACPS deactivated at a decomposition temperature of 850 °C decreased with an increase in conversion, while they increased for the ACPS deactivated at a decomposition temperature of 950 °C; the activation energies varied between 81 and 163 kJ/mol. The gasification reactivity changed with methane conversion, showing maximum values for both the virgin and deactivated ACPS at a decomposition temperature of 950 °C. The initial gasification reactivity of the catalyst decreased after three gasification cycles at 1000 °C, while no significant change was observed with gasification cycles at 950 or 900 °C.     

An end-use energy analysis in a Malaysian public hospital

The commercial sector consumes 8–50% of the total energy consumption for a few selected countries around the world. An energy audit was conducted in a Malaysian public hospital to identify energy using equipment and their energy consumption breakdown. Different energy saving measures have been identified and applied for electrical motors used in this hospital. It was estimated that this hospital consumed about 19,311 MW h for the year 2008. It was also estimated that about 212 MW h, 250 MW h and 317 MW h of annual energy can be saved using energy-efficient motors at 50%, 75% and 100% loads, respectively. In addition, use of variable speed drives are expected to save 1735 MW h, 4048 MW h and 6361 MW h of annual energy consumption for 20%, 40% and 60% speed reductions, respectively. It was found that the payback period for using high efficiency motors at different loads is less than a year which is economically very viable. However, the use of variable speed drives was found to be economically viable for larger motors for higher speed reductions. The study also found that a sizeable amount of emissions can be reduced for the different energy savings measures applied for electrical motors.     

Composition and thermal analysis of ternary mixtures of avocado fat:palm stearin:cocoa butter (Avo:PS:CB)

Avocado fat is a semi-solid substance with potential functional lipid characteristics. A study was carried out to evaluate the effect of addition of palm stearin and cocoa butter on the solidification behavior of avocado fat to formulate a mixture to become similar to lard. A total of three mixtures were prepared: avocado fat:palm stearin:cocoa butter (88:7:5), avocado fat:palm stearin:cocoa butter (86:7:7), avocado fat:palm stearin:cocoa butter (84:7:9; w/w), and identified by the mass ratio of avocado fat to palm stearin and cocoa butter. The fat mixtures were compared with lard in terms of the fatty acid and triacylglycerol compositions using gas chromatography and high-performance liquid chromatography, thermal properties using differential scanning calorimetry and solid fat content using p-nuclear magnetic resonance. Although there were considerable differences between lard and the fat mixtures with regard to fatty acid and triacylglycerol compositions, some similarities were seen with regard to thermal properties and solid fat content profile. Of all the fat mixtures, avocado fat:palm stearin:cocoa butter (84:7:9) displayed closer similarity to lard with respect to thermal transitions at –3.59°C and its solid fat content profile showed the least difference to that of lard throughout the temperature range measured.     

Design factors affecting the dynamic performance of soil suspension in an agitated,baffled tank

The effects of particle size, impeller clearance and impel er speed are assessed to show how condition variations influence power consumption in the water-solid slurry suspension in an agitated tank. The energy efficiency of slurry height variation, impel er type and diameter, and solid movement speed has been investigated with six soil series stirred in a soil-water slurry. Coarser sand particles are observed to significantly increase power consumption, while finer particles, for instance clay, decrease the stirring power requirement. The 3-blade HR100 SUPERMIX? impeller manufactured by SATAKE general y performs more efficiently than a conventional 4-pitched blade turbine. The impeller's geometric design, including diameter and number of blades influences the impeller's energy efficiency, and HR100 impellers with greater diameters remarkably reduce power consumption. The tests demonstrated that the power required to provide off-bottom solid suspension and solid dispersion can be reduced dramatically by increasing the slurry height rather than by accelerating the impel er, if this option is possible.     

Determination of kinetic parameters for thermal decomposition of bamboo leaf to extract bio-silica

Bio-silica has many applications due to its high reactivity and pozzolanic properties. The extraction of silica from biomass such as bamboo leaf is usually accomplished by thermal decomposition. Currently, the thermal decomposition requires external heat energy input. In this work, the possibility to reuse the heat released during thermal decomposition to make the process self-sustained is explored. The kinetic parameters of the combustion were determined by fitting thermogravimetric analysis (TGA) data to the Flynn–Wall–Ozawa model, where the corresponding activation energy and frequency factor are 211.7 ± 3.8 kJ mol^?1 and 4.5 × 10¹⁵ s^?1, respectively. The lower heating value of bamboo leaf determined is 8.709 kJ g^?1, which is comparable to common wood fuels. Hence, the heat released in the combustion of bamboo leaf can be reused to make the process self-sustainable.     

Eco-friendly biodiesel production from olive oil waste using solar energy

This study was carried out to produce biodiesel from olive oil waste by transesterification reaction. Several important reaction variables (the weight ratio of oil to methanol, the temperature, and reaction time) were evaluated to obtain a high quality of biodiesel fuel that meets authentic standards. Solar energy was applied for the transesterification reaction and electricity generated by photovoltaic panels was used to power a motor for mixing the reaction solution.     

Productivity enhancements of compound parabolic concentrator tubular solar stills

The performance of compound parabolic concentrator assisted tubular solar still (CPC-TSS) and compound parabolic concentrator-concentric tubular solar still (CPC-CTSS) (to allow cooling water) with different augmentation systems were studied. A rectangular saline water trough of dimension 2 m × 0.03 m × 0.025 m was designed and fabricated. The effective collector area of the still is 2 m × 1 m with five sets of tubular still – CPC collectors placed horizontally with north-south orientation. Hot water taken from the CPC-CTSS was integrated to a pyramid type and single slope solar still. Diurnal variations of water temperature, air temperature, cover temperature and distillate yield were recorded. The results showed that, the productivity of the un-augmented CPC-TSS and CPC-CTSS were 3710 ml/day and 4960 ml/day, respectively. With the heat extraction technique, the productivity of CPC-CTSS with a single slope solar still and CPC-CTSS with a pyramid solar still were found as 6460 ml/day and 7770 ml/day, respectively. The process integration with different systems cost was found slightly higher but the overall efficiency and the produced distilled water yield was found augmented.