Performance of Diesel Engine Using Diesel B3 Mixed with Crude Palm Oil

The objective of this study was to test the performance of diesel engine using diesel B3 mixed with crude palm oil in ratios of 95 : 5, 90 : 10, and 85 : 15, respectively, and to compare the results with diesel B3. According to the tests, they showed that the physical properties of the mixed fuel in the ratio of 95 : 5 were closest to those of diesel B3. The performance of the diesel engine that used mixed fuels had 5–17% lower torque and power than that of diesel B3. The specific fuel consumption of mixed fuels was 7–33% higher than using diesel B3. The components of gas emissions by using mixed fuel had 1.6–52% fewer amount of carbon monoxide (CO), carbon dioxide (CO2), sulfur dioxide (SO2), and oxygen (O2) than those of diesel B3. On the other hand, nitric oxide (NO) and nitrogen oxides (NOX) emissions when using mixed fuels were 10–39% higher than diesel B3. By comparing the physical properties, the performance of the engine, and the amount of gas emissions of mixed fuel, we found out that the 95 : 5 ratio by volume was a suitable ratio for agricultural diesel engine (low-speed diesel engine)

Preparation and selection of a eutectic phase change material for cooling the PV module under Thailand climatic conditions

Several studies have found that incorporating an appropriate melting temperature (Tmelt) of Phase Change Material (PCM) behind the PV module enhances the cooling effect. In this study, PCM is selected for hybrid cooling for summer and winter using six years of meteorological data obtained from NASA. Considering the hybrid cooling method, winter season Tamb is selected to optimize the Tmelt as the selected PCM must reach the latent heat property in an early sunshine. It is found that during winter, 70 % of the period, Tamb lies around 28 °C whereas the Tmelt of PCM should be in the range of 31-34 °C according to the modified optimization method. In total, twelve combinations of eutectic mixtures are prepared using Lauric Acid (LA), Myristic Acid (MA) and Stearic Acid (SA), and their thermophysical properties are analysed using a differential scanning calorimeter. Only seven eutectic mixtures attain the 31-34 °C Tmelt among that LA:MA (70:30) and LA:SA (70:30) show excellent latent heat of fusion of 194 J/g and 190 J/g, respectively. Furthermore, it is recommended that LA:MA (70:30) and LA:SA (70:30) are suitable for Thailand’s climatic conditions for PV module cooling

Comparative study for photovoltaic cooling using metal mesh inserted eutectic phase change material enclosure

Phase change material (PCM) is a predominant storage material that enables a higher cooling effect over sensible heat storage materials without the assistance of working fluid. In this study, novel PCM infused finned, and mesh finned containers are developed to help cooling photovoltaic (PV) in operation by reducing the PCM conduction resistance. The designed container is integrated underneath the back surface of the PV module and experimented under controlled weather conditions (indoor). Fins are attached behind the PCM container without any intermediate layer favors transferring the heat from the top to the bottom fin surface as a single unit. The main benefit of a PCM-infused fin container enhances the PCM liquid flow movement throughout the finned morphology and the heat dissipation rate increases between the finned PCM container and its surroundings. Moreover, incorporating metal mesh inside the PCM container resulting to the control of the conduction barrier and increased the heat transfer rate. It is found that metal mesh based finned PCM container shows an excellent performance enhancement between 85th and 150th minutes with a peak cooling of 2.20% and corresponding to the electrical power and energy productions of 2.01% and 2.71%, respectively compared to finned PCM container. The statistical approach on finned and mesh finned PCM containers shows that ambient temperature has a strong positive correlation with the temperature rise in photovoltaic resulting in performance degradation. Furthermore, it is recommended that the developed PCM containers are suitable for tropical climatic conditions to improve the PV power output

Minimization of Losses in Solar Photovoltaic Modules by Reconfiguration under Various Patterns of Partial Shading

Configurations of photovoltaic (PV) modules, such as series-parallel (SP), bridge-linked (BL), and total cross-tied (TCT) configurations, always utilize a number of connecting switches. In a simulation, the ideal switch with no loss is used to optimize the reconfiguration method for a solar PV array. However, in practice, the switches are non-ideal, causing losses and resulting in a decrease in the total output power of the PV array. In this work, MATLAB/Simulink (R2016a) was employed to simulate nine PV modules linked in a 3 × 3 array, and they were reconfigured using series-parallel (SP), bridge-linked (BL), and total cross-tied (TCT) configurations for both ideal and non-ideal switch cases. It was not surprising that non-ideal switches deteriorated the output power compared with ideal cases. Then, the minimization of losses (ML) configuration was proposed by minimizing the number of switches to give the highest output power. A 5% higher power output was set as the criterion to reconfigure the PV modules when partial shading occurred. The results showed that if 50% or more of the area was partially shaded, reconfiguration was unnecessary. On the other hand, when the shaded area was less than 50%, reconfiguration gave a significant increase in power. Finally, the ML method had different configurations for various shading patterns, and provided better results than those of the TCT method

Energy Management for an Air Conditioning System Using a Storage Device to Reduce the On-Peak Power Consumption

To reduce the on-peak electrical power consumption, storage devices are widely performed with the help of an energy management system. According to IEA, residential air conditioning consumes 70% of the electricity, increasing by 4% every year. To minimize peak power consumption, thermal energy storage (TES) can be used to store cooled water for the air conditioning system. An efficient chilled water tank was designed and computationally investigated. Three-dimensional cylindrical tanks were simulated with seven different heights to diameter (H:D) ratios. At first, the temperature changes in a chilled water tank during discharging and charging periods were studied. An 11-h charging period was carried out during the off-peak time at night, while the discharging period was 13 h during the daytime. Under time constraints regarding peak and off-peak periods, a tank with an H:D = 2.0 can only be used for 13-h discharging. Then the chilled water was simulated with a set temperature of 4 °C during the charging. This resulted in the system being usable for six days, after which it had to be stopped for longer charging. A storage tank with an H:D ratio of 2.0 was found to be suitable for an air conditioning system. If six days of operations (one day off) were used, it could save 15.38% of electrical energy consumption and 51.65% of electricity cost. This saving leads to a 5.55-year payback period

Impact of positive and negative pressure on rice straw torrefaction: Optimization using response surface methodology

Biomass powers have been recently increased in Thailand, over demand of biomass has become a problem led to finding out alternative agricultural waste to be used as fuel. Rice straw is one of promising biomass with very high quantity and quality. However, upgrading rice straw could be more attractive. Rice straw, an agricultural waste, has been interested in being prepared as the renewable energy resource for industrial scale. In 2019–2021, rice straw was estimated to be 15 Mton/year and left on fields after harvesting. Its heating value is approximately 12 MJ/kg, and thus the energy could be 180 × 106 GJ/year. The objective of this study is to enhance the fuel properties of rice straw using torrefaction technology. The effect of positive and negative pressure (−0.4, 0.8 and 2 barg) on energy yield (EY) and specific energy consumption (SEC) was initially investigated at temperature and time of 200 °C and 40 min, respectively. It was found that the positive pressure of 2 barg gave the highest EY of 94.95%, but the SEC was higher than the condition while applying negative pressure (−0.4 barg). Furthermore, the factors of temperature, time, and pressure were designed to study their combined effects on EY and SEC. The ranges of temperature, time, and pressure for torrefaction of rice straw were 200–220 °C, 30 to 50 and -0.4 to 2 barg, respectively. The response surface methodology based on central composite design using Minitab V.18 program was investigated on two responses (EY and SEC). It was found that severe conditions gave lower mass yield but they resulted in higher heating values of the torrefied rice straw. However, higher energy was consumed during the process. The maximum EY of 94.43% and minimum SEC of 21.94 Wh/g were obtained at the optimum conditions of 200 °C, 30 min and −0.4 barg. In addition, from the proximate and ultimate analysis, the torrefied rice straw by this optimal condition had better fuel properties than the raw one due to higher fixed carbon (FC), hydrogen to carbon ratio (H/C) and oxygen to carbon ratio (O/C)

Experimental Studies on PV Module Cooling With Radiation Source PCM Matrix

Rise in PV module temperature ( $\text{T}_{\mathrm {PV}}$ ) majorly drops the electrical output of the PV system. This research presents a novel cylindrical tube PCM matrix that is not in physical contact with the PV module back surface unlike the existing PCM based PV module cooling techniques. This contactless PCM matrix prevents the PV module from thermal and physical stress, also it blocks thermal energy re-conduction from PCM to PV module. While stored thermal energy from PCM retransferred to the PV module during off-sunshine hours and also when the PCM turns to liquid $\text{T}_{\mathrm {PV}}$ starts to rise abruptly, this contactless PCM matrix minimizes these issues as PCM matrix receives thermal energy by the mode of radiation and convection; Besides, PCM matrix surface area is not enclosed with the PV module back surface area that reduces the thermal stress and re-conduction. Developed PCM matrix is integrated beneath the PV module at particular distances of 6 mm, 9 mm and 12 mm to optimize the spacing between PV module and PCM matrix. It is found that 6 mm spacing PCM matrix reduced the $\text{T}_{\mathrm {PV}}$ maximum of 2.5 °C compared to 9 mm and 12 mm spacing. This $\text{T}_{\mathrm {PV}}$ reduction enhanced the PV module electrical output by 0.2 % than PV without PCM and it is observed that 6 mm is an optimal spacing for the radiation source PCM matrix