Abstract Spiral tube heat exchangers (STHE) are coiled metal devices with two fluid channels around a central core, enabling counterflow or parallel flow of gases, liquids, or both. Compared to traditional straight-tube heat exchangers, STHEs offer a larger heat transfer surface area. This study used Computational Fluid Dynamics (CFD) simulation integrated with Computer Aided Design (CAD) to investigate STHE’s heat transfer performance. The STHE dimensions, a 12-mm copper tube, and a 10-inch PVC shell were adopted from a previous study. Cold and hot water at 20°C and 70°C flowed in parallel at specific flow rates. The objective was to explore the impact of STHE dimensions on heat transfer efficiency and performance. The parameters varied were the internal diameter of the copper tube and the number of spiral coil windings. Results revealed that changing the spiral heat exchanger’s diameter affected the heat transfer rate and coefficient. Larger diameters reduced efficiency due to lower flow velocities and convective heat transfer coefficients. The number of windings significantly affected heat transfer performance, with winding 5 demonstrating the highest rate and winding 7 showing the highest coefficient. CFD analysis reliability was validated by convergence with analytical solutions for heat transfer simulations with varying diameters and windings.

This study investigates the influence of varying concentrations of boric acid (BA) preservative on the physical and mechanical properties of light red meranti (LRM) found in Sarawak. LRM or Shorea leprosula samples were treated with various concentrations of BA via the dip diffusion method using American Society for Testing and Materials (ASTM) standards. The physical property, particularly the retention rate and mechanical properties, bending strength, modulus of elasticity (MOE), tensile and compression strength parallel to grain of impregnated and control samples were tested to determine the effects of BA preservative. The retention rate was found to increase with increasing BA concentration and higher surface area to volume ratio. The mechanical properties in terms of the MOE and tensile strength parallel to grain were found to be greater than those of the control samples, whereas the bending strength and tensile strength parallel to grain were lower. Amongst the results, only the retention rate and MOE showed significant interaction effects at 5% level of significance between all factors tested (samples size and BA concentration for retention rate and BA concentration for MOE).

Recycled fibers often demonstrate diminished conformability and inter-fiber bonding capabilities in comparison to virgin fibers due to hornification. However, the untapped potential of recycled pulp can be restored through various techniques, such as mechanical beating, additive utilization, physical fractionation, and blending. This research focuses specifically on the blending method, which utilizes oil palm frond fibers to augment the strength of paper produced from recycled pulp. Despite the extensive cultivation of oil palm trees in Malaysia, the utilization of oil palm fiber remains limited and is frequently considered waste material. Two distinct chemical pulping methods, namely sodium hydroxide and sodium sulfite, were employed to generate pulp from oil palm frond fibers, incorporating anthraquinone as an additive to enhance pulping efficiency. Three different weight percentages of fiber loading (25%, 45%, or 65%) were utilized, with the remaining content supplemented with newspaper pulp. The resultant paper was assessed for tensile strength, modulus of elasticity, and its morphology was examined using scanning electron microscopy. The findings indicate that the sulphite-soda anthraquinone treatment resulted in superior pulp for paper production, and a weight percentage of 45% fiber loading exhibited the highest tensile strength, thus yielding the highest quality paper. Overall, this study underscores the potential of integrating oil palm frond fibers into the pulp and papermaking process, thereby contributing to both economic growth and environmental sustainability.

At present, rigorous research are carried out to produce the finest possible properties of composite materials. This phenomenon has made it possible to expand the application of composite laminates, which originally meant for only defence and aeronautical industries towards more public and general applications. To avoid catastrophic failure of composite structures, its failure behaviour should be established. Nevertheless, composite laminates may deform in various modes and thus, these modes of failure should be well understood before designing a composite structure, especially with the cutouts. This paper aims to study the effect of the circular cutout on the failure behaviour of Kevlar Epoxy and Glass Epoxy composite laminates with various fibre orientations. The work was conducted in two stages. The preliminary work involved mesh convergence analysis and numerical validation. The laminate modelling and failure analysis was performed using a finite element software (ANSYS). The model with stacking sequence is [θ4/04/−θ4]s and various fibre orientation, θ from 0° to 90° were investigated. Failure was determined using Maximum Stress Theory. The results show substantial strength reduction between composite laminates with and without circular cutout. Comparing Kevlar Epoxy and Glass Epoxy at 0° fibre angle, the results show that the circular cutout has more influence on Kevlar Epoxy (10 times weakened) than the Glass Epoxy (3 times weakened). However, when the fibre angle varied, both composites exhibit the similar trend of failure. Therefore, it is proven that the current study is essential in understanding the failure behaviour of composite plates with circular cutout.

A study was conducted to explore the effect of palm oil boiler ash (POBA) on foamed concrete by varying the percentage of POBA over sand quantities (0, 4, 8 and 12%). This paper primarily discusses the water absorption test, uniaxial compressive strength, and dry density findings. It indicates that substituting sand with POBA greatly enhances the strength of foamed concrete. When the quantity of POBA was raised up to 12% throughout all curing times, the compressive strength steadily increased in the range of 4.34–13.50 N·mm–2. Furthermore, the dry density of foamed concrete was shown to be directly related to the fraction of POBA in the mixture. The dry density of foamed concrete increases as the amount of POBA increases. Despite this, water absorption shown that increasing POBA increases water absorption percentage in foamed concrete from 7.4 to 10.4%. This is due to the fact that a composition with a high POBA percentage will generate more pores than a mixture with a low POBA percentage.

Due to the demand of reducing costs for high strength materials, hybridizing composite laminates could offer the alternative in producing materials with superior properties at reduced costs. Moreover, preparing samples and conducting experiments for these materials are very costly and tedious. Therefore, in order to establish the complex failure behavior of hybrid composite laminates, finite element analysis and simulation has been the choice for failure prediction. Accepting, this challenge, this paper investigates the deformation and failure behavior of composite plates made of woven Kevlar Epoxy (KE), unidirectional Glass Epoxy (GE), and their hybrids (KE/GE) under uniaxial tension. Solid plates and plates with circular hole were modeled using commercial finite element software, ANSYS APDL. In general, all laminates having the layup of [θ4/04/-θ4]s but the hybrid laminate arrangement varies between the number of GE and woven KE laminates. Using the built-in failure criteria function provided by ANSYS APDL, the first ply failure (FPF) and last ply failure (LPF) loads for several configuration of hybrid laminates were determined. In addition, the angle of fiber orientation, θ, was varied from 0° to 90° to generate the trend of failure curves. The results show that the FPF and LPF curves for the plates with hole are lower compared to the solid plate. Nevertheless, the patterns of the failure curves are very much influenced by the angle of fiber orientation. This indicates that the fiber angles have a significant effect on the strength of hybrid composite laminates. Compared to GE and woven KE composite laminates, the hybridization between unidirectional lamina and woven lamina could also influence the pattern of the failure curves. It could be concluded that the current study is useful; and has provided knowledge about the failure and deformation behavior of hybrid composite laminates by combining unidirectional (GE) and woven (KE) laminates.

Copper is well known as a valuable material, particularly for electrical industries due to its excellent properties. Besides, the price for copper scrap is also higher in comparison with other metal scrap materials found in many electrical appliances such as computer equipment, electric motor, transformer, and other components. This paper describes the potential of recycled copper wire shaped into a form suitable for heat sink application. The samples of wire mesh for this research were fabricated by compacting copper wire with different weight. Compaction was done to form a cylindrical shape with a diameter and height of approximately 25 mm and 30 mm, respectively. These samples were evaluated for porosity, thermal conductivity, and permeability. The experimental results showed that the sample with the lowest porosity exhibited great promising conductivity. In addition, lowering the amount of copper wire in compaction resulted in low density, thus improved its lightweight properties. The greater amount of porosity resulted in greater permeability. The optimum properties with a combination of the excellent thermal conductivity and permeability are necessary for heat sink application to ensure that the parts work effectively.

Algae-diesel has received a great interest as a source of biodiesel because it has the potential of meeting the global demand for transport fuel. The algae oil is mixed with diesel and iso-butanol to investigate the effect on the exhaust emission of a diesel engine. The test was performed in a four stroke, single cylinder, air cooled diesel engine at a constant speed of 1500 rpm for five fuel samples. The exhaust emissions tests revealed that the addition of 4.5 % of iso-butanol in algae-diesel blends, release more CO and NOx emission due to the increase in the content of oxygenated fuel.

In this paper study the properties of Palm Boiler Ash (POBA) as sand and cement replacement in concrete and identify optimum level of replacement. Besides that, pozzolanic activity of the POBA to OPC also has been assessed. Samples were tested to measure its compressive strength, ultra-pulse velocity (UPV), and thermal conductivity of blended concrete. Three replacement level of sand and cement has been employed which are 5%, 10%, and 15%. It is found that, increased in the POBA replacement level in the cement mixture will linearly reduce the compressive strength of concrete mixture. From perspectives of pozzolanic activity, it is increases as amount of POBA replacement increases. For UPV values, it is decreases as POBA replacement increases. Among those three percentage of sand and cement replacement, 5% POBA replacement is the most optimum quantity of the POBA replacement in the concrete as it shows a high compressive strength when tested for compression strength, good quality of concrete grade and thermal conductivity of 1.54 W/m.K.

Current conventional cool boxes which use expanded polystyrene (EPS) as its insulating material cannot seem to maintain storage at low temperature for long periods. This study aims to determine the effect for different types of insulating materials which can be used in cool boxes to improve its thermal insulation. Using theoretical and simulation approach, three out of six potential insulating materials were chosen in terms of their heat transfer rate, and temperature at the outer wall. The three best insulating materials, polyurethane (PU), expanded polystyrene (EPS) and poly-glass fibre (PGF) were then tested at three different room temperatures experimentally using the thermal insulation test to determine the best insulating material for a cool box. Tensile and density were also conducted to identify the mechanical behaviour and properties of these insulating materials. From the results obtained from the experiment, polyurethane (PU) recorded the longest time taken for ice to change into water at the three different temperatures when compared to other insulating materials. The results showed that when thermal conductivity is low, the heat transferred through the walls of the cool box was also low thus resulting in better thermal insulation of the cool box. This study gives a better understanding in term of thermal insulation and the results obtained from this study can help with the production of better cool boxes with improved thermal insulation.

Article history: Received 12 October 2016 Received in revised form 1 December 2016 Accepted 2 December 2016 Available online 11 December 2016 This paper investigates the severity level of wear metals occurred in Perodua MyVi 1300cc automatic transmission (AT) mechanism via multi-elemental spectrometric oil analysis. The work of analysis was performed merely on automatic transmission fluid (ATF) Perodua original equipment manufacturer (OEM) (ATF-3) series. The ATF was analyzed through actual operating distances. The operating mileage observed and analyzed was divided into three main categories. Category sample number (S1-S6) categorized as travelling distance (TD1) between 800km up to less than 20,000km travelling distance. Sample number (S7-S17) and (S18-S26) were each representing the operating travelling distance (TD2) and (TD3) encompassed of 20,000km up to less than 40,000km and 40,000km up to less than 60,000km, respectively. This analysis is primarily commenced based on limitations of the wear particle size that usually expressed as wear concentration in parts-per-million (ppm) unit. The typical concentration range for every element is between 1-100 ppm and the severity level of concentration for every element varies from one another. The element of Aluminum (Al), Chromium (Cr), Copper (Cu), (Ferum) Fe, Lead (Pb), Nickel (Ni), Tin (Sn), Titanium (Ti), Vanadium (V), Manganese (Mn), Argentum (Ag), Cadmium (Cd) are principally categorized as the wear elements. Barium (Ba), Boron (B), Calcium (Ca), Magnesium (Mg), Molybdenum (Mo), Phosphorus (P), Silicon (Si), Natrium (Na) and Zinc (Zn) are considered as additive elements which is subject to deplete and contaminate during used. From the analysis commenced, it was observed that the elements of Fe, Cu and Al were the most significant wear elements occurred throughout each operating categories and the occurrence of oxidation to be considered minimal as the element of phosphorus increases which indicates no sign of additive depletion to occur though the ATF had been used beyond its recommended period.

Continuous need for the optimum conversion efficiency of polymer electrolyte membrane fuel cell (PEMFC) operation has triggered varieties of advancements, namely in the thermal management engineering scope. Excellent heat dissipation is correlated with higher performance of a fuel cell, thus increasing its conversion efficiency. This study reveals the potential advancement in thermal engineering of a fuel cell cooling system with respect to nanofluid technology. Nanofluids are seen as a potential evolution of nanotechnology hybridization with the fuel cell serving as a cooling medium. The available literature on the thermophysical properties of potential nanofluids, especially on the electrical conductivity property, has been discussed. The lack of electrical conductivity data for various nanofluids in open literature was another challenge in the application of nanofluids in fuel cells. Unlike in any other thermal management system, a nanofluid in a fuel cell is dealt with using a thermoelectrically active environment. The main challenge in nanofluid adoption in fuel cells was the formulation of a suitable nanofluid coolant with heat transfer enhancement, as compared to its base fluid, but still complying with the strict limits of electrical conductivity as low as 2 S/cm and several other restrictions discussed by the researchers. It is concluded that a nanofluid in PEMFC is advantageous in terms of both heat transfer and simplification of the cooling system through radiator size reduction and potential elimination of the deionizer as compared to the current PEMFC cooling system. However, there are challenges that need to be well addressed, especially in the electrical conductivity requirement.

One of the methods to improve the combustion behavior in internal combustion engine is by introducing additive to the base fuel. However, some additive resulted in higher Brake Specific Fuel Consumption (BSFC) and emission of CO and NOx. The objective of this study is to examine the effects of fuel additives quantity to the fuel economy and engine emission. The tests were carried out at different engine speeds (1500rpm-3000rpm) and different engine loads (40Nm - 100Nm) using a four stroke gasoline engine. The additive was blended with gasoline (RON95) in composition of 5, 10 and 15 milliliter per liter accordingly. BSFC was measured using Pro V2 software and exhaust emission was measured using MRU AIR gas analyzer. Results showed that gasoline blended with 5ml fuel additive lead to a significant improvement on (BSFC) and higher carbon dioxide (CO2) in its emission. Base fuel blended with 10ml/l and 15ml/l additive showed increasing in BSFC.

Improving fuel consumption with lower exhaust emissions give more focused to all car manufactures. A higher engine performance with lower exhaust emissions requires a complete mixing process resulted in ultra-lean high combustion efficiency. Air intake temperature is one of the alternative strategies to improve fuel consumption and reduced exhaust emissions. This is due to the cold air is denser and contain higher oxygen availability. Air intake temperature will affect to the oxygen concentration in the charged air that influence the combustion process through ignition delay and fuel burning rate. The objective of this experiment is to investigate the effects of air intake temperature to the fuel consumption and exhaust emission at variation of engine speeds and constant load by using 1.6L gasoline engine. Air intake temperature was changed from 20 °C to 30 °C. The DaTAQ Pro V2 software was used to measure the engine fuel consumption while gas analyzer (MRU Gas Analyzer) was used to measure the exhaust emission such as Unburned hydrocarbons (UHCs) and carbon monoxide (CO). The results showed that fuel consumption, UHCs and CO emissions increased with the increase of air intake temperature. The increase of air intake temperature resulted in advanced and shorter combustion duration. Higher oxygen concentration at lower air intake temperature leads to the complete mixing process and complete combustion. Therefore, the experimental results can be concluded that the lower air intake temperature resulted in improved fuel consumption and reduced UHCs and CO emissions.

The sudden increase in fuel prices due to diminishing petroleum resources and the pollution resulting from its use has resulted in research into alternative fuels such as biodiesel. In addition, the faster combustion and high temperature in the combustion chamber which results from petroleum diesel fuel leads to higher nitrogen oxide (NOx) and Particulate Matter (PM) emissions. Therefore, this research was conducted to investigate the effect of using palm oil methyl ester (POME) blends as alternative fuels on the performance and emission of a compression ignition engine. The performance of POME blends and diesel were compared by manipulating the load of the engine at 1800 rpm. The results obtained show that fuel consumption rate is higher for the POME blends compared to the diesel fuel and increases as the POME concentration increases. The increment of brake specific fuel consumption and the reduction of CO emission exhibit a relation to the increase in percentage of POME. This is mainly contributed by the higher oxygen content of POME which promotes complete combustion of the blends. However, efficient combustion from the blends as compared to diesel fuel resulted from higher oxygen content and cetane number leads to significant increase in exhaust temperature. This in turn increases NOx emissions since using POME blends is highly related to high temperature of combustion chamber. The experimental results proved that POME in compression ignition engine is a possible substitute to diesel.

Keywords:Thermal management; PEM fuel cell;NanofluidAbstract. Tremendous need for an optimum conversion efficiency of a Polymer Exchange Membrane Fuel Cell (PEMFC) operation has triggered varieties of advancements namely on the thermal management engineering scope. Excellent heat dissipation is correlated to higher performance of a fuel cell thus increasing its conversion efficiency. This study reveals the potential advancement in thermal engineering of a fuel cell stack related to nanofluid technology. Nanofluids are seen as a potential evolution of nanotechnology hybridisation with fuel cell serving as a cooling medium. The thermophysical characteristics have been reviewed and challenges with regards to fuel cell application is discussed. Nanofluid has been successfully tested on many thermal management systems isolated from thermoelectrical environments such as fuel cell. The main challenge is formulating a nanofluid coolant with high thermal conductivity but with strict limit on electrical conductivity of less than 5 μS/cm. Lack of electrical conductivity data for various nanofluids in open literature is another challenge in nanofluid application in fuel cell.

Biodiesel is used widely as an alternative fuel for diesel engine due to biodegradable, oxygenated, renewable and compatible with diesel engines. In fact, biodiesel emission has decreased the levels of potentially carcinogenic compounds. However, a certain biodiesel such as Jatropha Oil Methyl Ester (JOME) has resulted in the increase of specific fuel consumption and higher NOx emissions. Therefore, the objective of this study is to investigate the effects of Palm Oil Methyl Ester (POME) in the blended fuel (Fossil fuel + JOME) on the fuel consumption and exhaust emission. Experiments were carried out at a constant engine speed (2000 rpm) with variable of engine loads. Results show that the addition of POME leads to the significant reduction in brake specific fuel consumption (BSFC), Total hydrocarbons (THCs), carbon monoxide (CO) and nitrogen dioxide (NOx) emissions. This study shows a huge difference for Total hydrocarbons emission of blends with 5% POME compared to blends with 10% and 15% of POME. Carbon monoxide emission for blends with 15% POME is the lowest at constant engine speed with various engine loads which in average is 53% lower than blends of 5% POME. This is because blends with higher percentage of POME has higher cetane number hence shortened the ignition delay resulted in the lower possibility of formation of rich fuel zone and thus reduces CO emissions. Moreover, the higher percentage of POME also resulted in lower NOx emission regardless of engine loads. The blends with 15% POME had the lowest NOx emission which is 25% less compared with the blends of 5% POME. The study recommended that, additional POME to the blended fuel can be considered as a good initiative to improve blended fuel property for diesel engine due to its potential to improve engine emissions and reduce brake specific fuel consumption. In conclusion, the blends of POME into (Fossil fuel + JOME) improves engine emission without significantly increasing fuel consumption.

Continuous need for the optimum conversion efficiency of polymer electrolyte membrane fuel cell (PEMFC) operation has triggered varieties of advancements, namely in the thermal management engineering scope. Excellent heat dissipation is correlated with higher performance of a fuel cell, thus increasing its conversion efficiency. This study reveals the potential advancement in thermal engineering of a fuel cell cooling system with respect to nanofluid technology. Nanofluids are seen as a potential evolution of nanotechnology hybridization with the fuel cell serving as a cooling medium. The available literature on the thermophysical properties of potential nanofluids, especially on the electrical conductivity property, has been discussed. The lack of electrical conductivity data for various nanofluids in open literature was another challenge in the application of nanofluids in fuel cells. Unlike in any other thermal management system, a nanofluid in a fuel cell is dealt with using a thermoelectrically active environment. The main challenge in nanofluid adoption in fuel cells was the formulation of a suitable nanofluid coolant with heat transfer enhancement, as compared to its base fluid, but still complying with the strict limits of electrical conductivity as low as 2 S/cm and several other restrictions discussed by the researchers. It is concluded that a nanofluid in PEMFC is advantageous in terms of both heat transfer and simplification of the cooling system through radiator size reduction and potential elimination of the deionizer as compared to the current PEMFC cooling system. However, there are challenges that need to be well addressed, especially in the electrical conductivity requirement.

Nanofluid is an emerging technology in heat transfer study. The effect of nanofluids as a cooling medium in liquid cooled Proton Exchange Membrane Fuel Cell (PEMFC) is studied. Nanofluids with 0.1% and 0.5% volume concentration of Al 2 O 3 are dispersed in base fluid of 50:50 mixture of Ethylene Glycol and water were analyzed experimentally. A rated power of 400 W liquid cooled PEMFC was used to verify the findings. The result showed that insignificant improvement in performance of PEMFC with nanofluids through polarization curve findings, perhaps due to the lower wattage of PEMFC used. The advantage of nanofluids utilization in PEMFC might be visible in higher wattage of PEMFC due to higher working fluid temperature. Higher thermal conductivity of nanofluid at higher temperature is expected to give advantage in terms of polarization curve of a PEMFC. However, the thermal performance is improved through the heat transfer rate increment of 68.5 % and 46 % for both 0.5 % of Al 2 O 3 nanofluid and 0.1 % of Al 2 O 3 nanofluid respectively.

Nanofluid is an emerging technology in heat transfer study. The effect of nanofluids as a cooling medium in Proton Exchange Membrane Fuel Cell (PEMFC) is studied. Nanofluids with 0.1% and 0.5% of Al2O3 dispersed in base fluid of 50:50 mixture of Ethylene Glycol and water were analyzed experimentally. A 400 W liquid cooled PEMFC was used to verify the findings. The result showed that insignificant improvement in performance of PEMFC with nanofluids, perhaps due to the lower wattage of PEMFC used. However, the thermal performance is improved through the heat transfer rate increment of 68.5 % and 46 % for both 0.5 % of Al2O3 nanofluid and 0.1 % of Al2O3 nanofluid respectively.