Thermal conductivity prediction of nano enhanced phase change materials: A comparative machine learning approach

Thermal conductivity is one of the crucial properties of nano enhanced phase change materials (NEPCM). Then, in this study three different machine learning methods namely MARS (Multivariate Adaptive Regression Spline), CART (Classification and Regression Tree) and ANN (Artificial Neural Network) is applied to estimate the thermal conductivity of NEPCMs. To develop these models, the information of the different types of NEPCM were collected from 25 studies. The nano particle includes CNF, h-BN, CBNP, GNP, MWCNT, TiO2, SiC, GO, CuO, ZrO2, EG and the PCMs were Paraffin, Polyethylene glycol, Dimethylformamide, Myristic acid, High Density Polyethylene, Phenol, Stearic acid, Erythritol, Eicosane, Palmitic acid and n-octadecane. The total number of samples were more than 911 data to train, test and validate the models. The input parameters for the model were thermal conductivity of nano particle and PCM (W/m.K), phase of NEPCM (solid or liquid), temperature of NEPCM ( °C) and concentration of nano material (wt%) and the output of the models was the thermal conductivity of the NEPCM (W/m.K). The results of the study showed the thermal conductivity of PCM is main effective parameter on the thermal conductivity prediction of NEPCM in all three models. Moreover, the accuracy of the predicted values by ANN model has shown the ability of the ANN to find relationship between dependent and independent variables complex problem and R2 for MARS, CART and ANN model were 0.93, 0.93 and 0.96, respectively. Furthermore, the phase of the NEPCM, which has been used first time uniquely as a predictor in this study, has been second important variable in the developed models. Then, the developed ANN model in this study, as the first general ANN model for prediction of the thermal conductivity of NEPCM for carbon, metal and metal oxide nano particles combined with different types of PCM, can be used to estimate thermal conductivity of various type of NEPCM

Performance and Emission Parameters of Single Cylinder Diesel Engine Using Castor Oil Bio-Diesel Blended Fuels

The purpose of this study is to investigate the performance and emission parameters of a CI single cylinder diesel engine operating on biodiesel-diesel blends (B0, B5, B10, B15 and E20: 20% biodiesel and 80% diesel by volume). A reactor was designed, fabricated and evaluated for biodiesel production. The results showed that increasing the biodiesel content in the blend fuel will increase the performance parameters and decrease the emission parameters. Maximum power was detected for B0 at 2650 rpm and maximum torque was belonged to B20 at 1600 rpm. The experimental results revealed that using biodiesel-diesel blended fuels increased the power and torque output of the engine. For biodiesel blends it was found that the specific fuel consumption (sfc) was decreased. B10 had the minimum amount for sfc. The concentration of CO2 and HC emissions in the exhaust pipe were measured and found to be decreased when biodiesel blends were introduced. This was due to the high oxygen percentage in the biodiesel compared to the net diesel fuel. In contrast, the concentration of CO and NOx was found to be increased when biodiesel is introduced

Improving the cooling performance of cylindrical lithium-ion battery using three passive methods in a battery thermal management system

Developing a high-performance battery thermal management system (BTMS) to keep the temperature of lithium-ion battery (LIB) in a suitable range has become of great interest for electric vehicle (EV) applications. Hence, this study has been set out to design a BTMS by utilizing various combination of phase change material (PCM), metal foam, and fins that keeps the battery surface temperature at the lowest level in normal and harsh environmental conditions under discharging with 3C current rate. Considering these three passive methods, four different cases of BTMS have been designed separately. Moreover, the effects of various fin shapes including rectangular, triangular, trapezoidal, I-shape, and wavy fins are studied for the optimum BTMS. The two-equation local non-equilibrium thermal model has been used which is more precise than the traditional thermal equilibrium model in simulating heat transfer between the PCM and metal foam. The numerical results demonstrated that the optimum BTMS, which is the combination of PCM, metal foam, and fins (fourth case), can reduce the battery surface temperature by 3 K. Furthermore, the maximum delay of about 470 s in melting of the PCM has been reported for this case. Additionally, the applied fins in the fourth case are acting as a network of heat sources to spread heat in the middle of the system, and utilized metal foam can create a uniform distribution of heat between LIB and ambient. Analyzing the effect of different fin shapes on the performance of optimum BTMS showed that there are no remarkable changes between the battery surface temperature of various fin shapes and it would be hard to find a suitable shape of fins for all environmental conditions

Physical properties of kumquat fruit

Some physical properties of kumquat were investigated. Physical properties which were measured included fruit dimensions, mass, volume, projected area, density, geometric mean diameter, sphericity and surface area. Bulk density, porosity and also packaging coefficient were calculated. Mechanical properties such as the elasticity modulus, rupture force and energy required for initial rupture have been determined. The experiments were carried out at moisture content of 82.6% (w.b.). The results show that the kumquat fruit is one of the smallest fruit in the citrus family

Physical properties of kumquat fruit

Some physical properties of kumquat were investigated. Physical properties which were measured included fruit dimensions, mass, volume, projected area, density, geometric mean diameter, sphericity and surface area. Bulk density, porosity and also packaging coefficient were calculated. Mechanical properties such as the elasticity modulus, rupture force and energy required for initial rupture have been determined. The experiments were carried out at moisture content of 82.6% (w.b.). The results show that the kumquat fruit is one of the smallest fruit in the citrus family

Experimental investigation of silver / water nanofluid heat transfer in car radiator

Currently available fluids for heat transfer including refrigerants, water, ethylene glycol mixture, etc., have been widely exploited in various fields, especially in automobile cooling systems, for many years. However, these fluids possess poor heat transfer capability which means that to achieve acceptable heat transfer activity, high compactness and effectiveness of heat transfer systems are essential. This research work concentrates on preparation and use of water based Silver containing nanofluids in automobile cooling system. Nanoparticles volume fraction, fluid inlet temperature, coolant and air Reynolds numbers were optimized so that the heat transfer performance of the car radiator system was totally improved. It was found that increasing these parameters leads to enhancement of the heat transfer performance. In the best condition, the Ag/water nanofluids with low concentrations could amend heat transfer efficiency up to 30.2% in comparison to pure water

Biofuel Combustion Generated Particles Analysis

Soot emission or carbon black is considered as a major challenge recently. Generally, internal combustion engines have been introduced as the main source of these materials specially in urban areas. Different methods are proposed to control soot emission of diesel engine such as DPF (Diesel Particulate Filter) which is attached to the engine exhaust line and the microstructure and size of NPs were introduced as important parameters on its efficiency. In addition, biodiesel has become widely accepted as an appropriate substitution for diesel fuel, however, the using of biodiesel fuel may change the structural characteristics of soot emission. It is observed that biofuel has higher soot oxidative reactivity, and it is more reactive than diesel fuel, which is an advantage for DPF regeneration. Smaller size of particles in biodiesel fuel soot compared to diesel fuel is mentioned as a reason for this phenomenon. For instance, it is reported that the fractal dimension of micro algae, cotton seed, waste cooking oil, eucalyptus oil, tea tree oil and diesel fuel is 2.02, 1.97, 1.85, 1.75, 1.80, 1.73, 1.69 (nm) respectively. Filtration efficiency which is a crucial characteristic of the DPFs for biodiesel fuel and diesel fuel was found to be much different. These differences are attributed to the morphology of the produced soot of the fuel burning. The source of the biodiesel fuel is introduced as an impactful parameter on engine NPs morphology and size. For example, the primary diameter of the soot emission from the above fuels is 20.1, 14.8, 14.8, 15.5, 14.5, 15, 17.5 and 20.75 nm, respectively. The result of these study reveals that structure and morphology of soot emission come from biofuel combustion is different from diesel fuel and these properties should be investigated for any unique biofuel resource individually. However, the smaller size of the biofuel combustion generated soot is an advantage of these fuels to enhance their oxidation reactivity