Temperature distribution in the three-layered upper mantle beneath a continent

Temperature distribution in the upper mantle underneath the continent, as well as temperature distribution in the lower mantle, is obtained. In the continental lithosphere, the solution to the heat transfer equation is obtained in the model of conduction heat transfer with inner heat within the crust. To calculate the temperature distribution in the upper and lower mantle, we use the results of laboratory and theoretical modeling of free convective heat transfer in a horizontal layer heated from below and cooled from above.

Numerical simulation of hydrogen arcjet thruster using coupled sheath model

In the present work, a complete 2D chemical and thermal non-equilibrium numerical model coupled with a relatively simple sheath model is developed for hydrogen arcjet thruster. Conduction heat transfer in the anode wall is also included in the model. The operating voltages predicted by the model are compared with those in the literature and are found to be in close agreement. Power distributions for the various operating conditions are obtained, anode radiation loss primarily determines the thruster efficiency. Higher thruster efficiency was found to be associated with longer arc length. At cathode ion diffusion contribution dominates except at low input current where thermo-field electron current is dominant.

Modeling and Assessing Heat Transfer of Piglet Microclimates

High piglet pre-weaning mortality rates can be attributed to poor creep area microclimate resulting in negative productivity, welfare, and economic consequences. A piglet mechanistic steady-state thermal balance model was developed using previous models and expanded to assess (a) thermal interactions of multiple pigs and (b) conduction heat transfer. The piglet Effective Environment Temperature (EET) equation was also modified to incorporate piglet age (day 0 to 30) and a conduction heat transfer term. Model parameters were validated with empirical data consisting of the thermal component (dry-bulb temperature, Tdb; mean radiant temperature, TMR; airspeed, U; mat underside temperature, Tm) of the microclimate and dimension data of the piglets (i.e., body weight, length, height, width, and calculated surface area). Model results demonstrate that the common microclimate supplemental heat sources (heat mats and heat lamps; HL) can meet the needs of the piglets. The new EET was more consistent for a novel semi-enclosed heated microclimate (SEHM) in comparison to the HL. This demonstrates the benefit of precision technologies over manually adjusted supplemental heat sources. The experimental data and model results suggest further development of an ideal thermal index for piglet microclimates needs to account for variations of piglet health and body condition to be more applicable in industry.

Thermal management of photovoltaic panel with nano-enhanced phase change material at different inclinations

Photovoltaic (PV) panel, coupled with phase change material (PCM), has attracted broad attention for the panel's thermal management. Despite the higher energy storage capability of PCMs, the main disadvantage is their low thermal conductivity which is compensated to an extent with the nano-enhanced PCMs (NEPCMs). In this study, numerical simulations are carried out to compare the natural convection phenomena and thermal response of PV-NEPCM with simple PV-PCM for various tilt angles. CuO nanoparticles with a 4% volume concentration are selected for NEPCM. The thermal performance of PV-NEPCM at inclinations of 0°, 15°, 30°, and 45\(^\circ\) are compared with a simple PV-PCM system. The average temperature of PV, liquid fraction and thermal energy stored in PCM, the PV efficiency are compared for PV-PCM and PV-NEPCM systems. Results show that the loading of nanoparticles increases the conduction heat transfer inside PCM. It has also been shown that at lower inclinations, the use of NEPCM is more effective due to the dominance of conduction heat transfer. At higher tilt angles, natural convection plays a significant role in the heat transfer mechanism inside PCM. By using NEPCM, the maximum decrease in PV temperature of 1.11\(℃\) and maximum improvement in the liquid fraction (7.6%) are achieved when \({\theta }=0^\circ\) compared to simple PCM. Enhancement of thermal energy stored in PCM increases slightly upon adding nanoparticles, and the highest improvement is obtained for \({\theta }=0^\circ .\) Maximum enhancement of PV efficiency is found to be 1.6% for \({\theta }=0^\circ\) inclination on adding nanoparticles at a fraction of 4 vol.%. Keywords: PV, nano-enhanced PCM, nanoparticles, natural convection, liquid fraction.

Assessment of the Physical, Mechanical, and Tribological Properties of PDMS Thin Films Based on Different Curing Conditions

Polydimethylsiloxane (PDMS), a silicone-based elastomeric polymer, is generally cured by applying heat to a mixture of a PDMS base and crosslinking agent, and its material properties differ according to the mixing ratio and heating conditions. In this study, we analyzed the effects of different curing processes on the various properties of PDMS thin films prepared by mixing a PDMS solution comprising a PDMS base and a crosslinking agent in a ratio of 10:1. The PDMS thin films were cured using three heat transfer methods: convection heat transfer using an oven, conduction heat transfer using a hotplate, and conduction heat transfer using an ultrasonic device that generates heat internally from ultrasonic vibrations. The physical, chemical, mechanical, and tribological properties of the PDMS thin films were assessed after curing. The polymer chains in the PDMS thin films varied according to the heat transfer method, which resulted in changes in the mechanical and tribological properties. The ultrasonicated PDMS thin film exhibited the highest crystallinity, and hence, the best mechanical, friction, and wear properties.

Predicting Conduction Heat Flux through Macrolayer in Nucleate Pool Boiling

In the current work, the heat flux in nucleate pool boiling has been predicted using the macrolayer and latent heat evaporation model. The wall superheat (ΔT) and macrolayer thickness (δ) are the parameters considered for predicting the heat flux. The influence of operating parameters on instantaneous conduction heat flux and average heat flux across the macrolayer are investigated. A comparison of the findings of current model with Bhat’s decreasing macrolayer model revealed a close agreement under the nucleate pool boiling condition at high heat flux. It is suggested that conduction heat transfer strongly rely on macrolayer thickness and wall superheat. The wall superheat and macrolayer thickness is found to significantly contribute to conduction heat transfer. The predicted results closely agree with the findings of Bhat’s decreasing macrolayer model for higher values of wall superheat signifying the nucleate boiling. The predicted results of the proposed model and Bhat’s existing model are validated by the experimental data. The findings also endorse the claim that predominant mode of heat transfer from heater surface to boiling liquid is the conduction across the macrolayer at the significantly high heat flux region of nucleate boiling.

Simulation of a Fast-Charging Porous Thermal Energy Storage System Saturated with a Nano-Enhanced Phase Change Material

The melting of a coconut oil–CuO phase change material (PCM) embedded in an engineered nonuniform copper foam was theoretically analyzed to reduce the charging time of a thermal energy storage unit. A nonuniform metal foam could improve the effective thermal conductivity of a porous medium at regions with dominant conduction heat transfer by increasing local porosity. Moreover, the increase in porosity contributes to flow circulation in the natural convection-dominant regimes and adds a positive impact to the heat transfer rate, but it reduces the conduction heat transfer and overall heat transfer. The Taguchi optimization method was used to minimize the charging time of a shell-and-tube thermal energy storage (TES) unit by optimizing the porosity gradient, volume fractions of nanoparticles, average porosity, and porous pore sizes. The results showed that porosity is the most significant factor and lower porosity has a faster charging rate. A nonuniform porosity reduces the charging time of TES. The size of porous pores induces a negligible impact on the charging time. Lastly, the increase in volume fractions of nanoparticles reduces the charging time, but it has a minimal impact on the TES unit’s charging power.

DESIGN AND ANALYSIS OF THERMAL SHOWCASE MINI AS A BEVERAGE COOLER USING A THERMOELECTRIC MODULE

In Indonesia, which has a tropical climate, a beverage cooler is needed. Almost every home, office, company, supermarket, and mall has installed beverage coolers. This has become a major necessity for people living in tropical countries. Especially those who live in eastern Indonesia, such as Ambon, NTT, and Papua, which have very hot temperatures. There are various types of use of the thermoelectric or peltier module, including food coolers, medicinal coolers, drinking water coolers in dispensers, and computer processor coolers. Besides being easy to apply, this tool is expected to be able to open up ideas in the use of thermoelectric modules that are more environmentally friendly than refrigerants. This research was conducted to obtain the size of the showcase mini design, the assembly process of the showcase mini tool, and to obtain the thermal analysis results contained in the showcase mini tool as a cooling medium. Showcase is a refrigerator that is used to display food or drinks that you want to display using glass media as a standout for the product being displayed. Thermoelectric technology is a technology that works by converting heat energy into electrical energy directly or vice versa, from electrical energy to produce cold energy. Thermoelectric is made of solid state material (solid material) which can convert energy from temperature difference to potential difference or vice versa. In this study, 2 variations of cooling load were used, namely without cooling load and with cooling load. Thermal analysis was carried out and got the results. The highest result from the calculation of conduction heat transfer load without cooling load is 0.013 Watt. The highest result from the calculation of the conduction heat transfer load with the cooling load is 0.010 Watt. The highest result from calculating the product heat load is 1.555 Watts. The highest result from the calculation of COP (Coefficient Of Performance) is 4,823. The expenses incurred each month are 16,000 rupiah.