Polyurethane (PU) materials are extensively used in the construction industry as core material insulation for sandwich panel application, such as wall cladding, structure insulation and roof panel. Demands on PU application have escalated given its significant advantages to reduce energy consumption. Meanwhile, rigid PU (RPU) foams are combustible materials characterized by rapid flame spread, high heat-release rates, and ability to produce large quantities of toxic gases in original form. Thus, flame-retardant (FR) additives are used to improve the thermal properties of PU. However, some commercial additives used today have are hazardous to humans and the environment, and their extensive application is limited by their negative effects on polymer mechanical properties. Accordingly, identifying materials that are environmentally friendly and harmless to humans has become urgent. Some alternative additives that are gaining research interest are clay and fly ash, which are natural and recyclable resources that can enhance the FR properties of other polymers. However, room for improvement is always present as the related technology is continually being developed. This review focuses on studies aiming to enhance the flame retardancy of RPU foam using fly ash and local clay as additives.

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Abstract. In this paper, an experimental study evaluating the effect of exhaust gas recirculation (EGR) and liquefied petroleum gas (LPG) onboard systems attached to a single cylinder DI diesel engine running with diesel is presented. Tests were performed at the minimum (1400 rpm) and maximum engine speeds (4100 rpm). The engine were tested under four different operating modes mainly; (a) standard test condition, (b) engine with EGR system, (c) engine with LPG system and (d) the engine with EGR and LPG onboard systems. Parameters that been measured during the tests are percentage of oxygen (O 2 ) content, carbon monoxide (CO) emissions, carbon dioxide (CO 2 ) and unburned hydrocarbon (UHC) emissions. Results show for the exhaust emissions, the engine with LPG onboard system emits higher CO and UHC emissions for both engine speeds. According to the experimental results it can be concluded that the use of EGR system increased the exhaust gas temperature and CO 2 emissions. While the engine with EGR and LPG onboard systems have influenced much on the increase in CO and UHC emissions for both engine speeds.

Abstract. Biofuel includes biodiesel is introduced to overcome the air pollution problems. Biodiesel is the sustainable and alternative fuel that derived from edible and non-edible oil produced from bio-originated species, plants, and animals. This paper presents the simulation analysis on the effect of fuel temperature variations on diesel engine performance and emission using palm-biodiesel. A one-dimensional numerical analysis, Diesel RK software is used to simulate a single cylinder, four-stroke diesel engine on the performance and emission when operated at a full load condition using fuel temperature variations ranging 300 K to 333 K. Results showed that simulated results for brake power and brake torque were 0.7% each when compared to the highest and lowest fuel temperature ranging from 333 K to 300 K. Moreover, higher fuel temperature for palm biodiesel tends to produce lower exhaust gas temperature and brake specific fuel consumption at a constant engine speed of 2400 rpm. It can be concluded that from the study, fuel temperature variations of biodiesel could produce a significant effect regarding engine performance and emission that influence the driving economy of the engine.

Biodiesel is among the solutions to substitute petroleum‐based fuel. However, the autoxidation ability of biodiesel, which results in degradation of the existing oxygen, has delayed its use on a global level. A potential solution to this problem is the addition of antioxidant additives. Palm oil methyl ester (POME) is the most popular biodiesel in Malaysia. Diesel 80% + POME 20% (B20) was added with two types of monophenolic antioxidant additives, which were butylated hydroxytoluene and butylated hydroxyanisole, at 1000 ppm and 1500 ppm concentrations, respectively, to examine their effects on combustion characteristics, engine performances and exhaust emissions. Hielscher UP400S ultrasonic emulsifier was used to prepare the fuel blends at 20% of the maximum stirring speed. Yanmar TF120M single‐cylinder diesel engine was employed at a constant speed of 1800 rpm with various engine loads. The results showed that B20 and antioxidant‐treated B20 produced a mean increase in brake specific fuel consumption of 8.33%–23.27% and reduced brake thermal efficiency by a mean that was 8.40%–24.95% greater than that of diesel fuel. Both antioxidants reduced nitrogen oxide emission by a mean of 12.92%–30.54%, compared to B20. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.