This contribution aims to appraise, analyze and evaluate the literature relating to the interaction of electromagnetic fields (EMF) with matter and the resulting thermal effects. This relates to the wanted thermal effects via the application of fields as well as those uninvited resulting from exposure to the field. In the paper, the most popular EMF heating technologies are analyzed. This involves on the one hand high frequency induction heating (HFIH) and on the other hand microwave heating (MWH), including microwave ovens and hyperthermia medical treatment. Then, the problem of EMF exposure is examined and the resulting biological thermal effects are illuminated. Thus, the two most common cases of wireless EMF devices, namely digital communication tools and inductive power transfer appliances are analyzed and evaluated. The last part of the paper concerns the determination of the different thermal effects, which are studied and discussed, by considering the governing EMF and heat transfer (or bio heat) equations and their solution methodologies.

The intermittent flow cold storage heat exchanger is one of the most important components of the pulse tube expansion refrigerator based on the reverse Brayton cycle. In the experimental system, the volume and heat transfer of the helical tube play a decisive role in the stable operation of the whole experimental system. However, there are few studies on heat transfer in a helical tube under helium working medium and intermittent flow conditions. In this paper, a process and method for calculating the volume of a helical tube are proposed based on the gas vessel dynamics model. Subsequently, a three-dimensional simulation model of the helical tube was established to analyze the heat transfer process of cryogenic helium within the tube. The simulations revealed that the temperature of helium in the tube decreases to the wall temperature and does not change when the helical angle exceeds 720°. Moreover, within the mass flow rate range of 1.6 g/s to 3.2 g/s, an increase in the mass flow rate was found to enhance the heat transfer performance of the helical tube. This study provides a reference for the selection and application of a helical tube under intermittent flow conditions and also contributes to the experimental research of inter-wall heat exchanger and pulse tube expansion refrigerators.

Heat transfer augmentation procedures, such as Heat Transfer Enhancement and Intensification, are commonly used in heat exchanger systems to enhance thermal performance by decreasing thermal resistance and increasing convective heat transfer rates. Swirl-flow devices, such as coiled tubes, twisted-tape inserts, and other geometric alterations, are commonly used to create secondary flow and improve the efficiency of heat transfer. This study aimed to explore the performance of a heat exchanger by comparing its performance with and without the use of twisted-tape inserts. The setup consisted of a copper inner tube measuring 13 mm in inner diameter and 15 mm in outer diameter, together with an outer pipe measuring 23 mm in inner diameter and 25 mm in outer diameter. Mild steel twisted tapes with dimensions of 2 mm thickness, 1.2 cm width, and twist ratios of 4.3 and 7.2 were utilised. The findings indicated that the heat transfer coefficient was 192.99 W/m² °C when twisted-tape inserts were used, while it was 276.40 W/m² °C without any inserts. The experimental results closely aligned with the theoretical assumptions, demonstrating a substantial enhancement in heat transfer performance by the utilisation of twisted-tape inserts. The study provides evidence that the utilisation of twisted-tape inserts resulted in a nearly two times increase in the heat transfer coefficient, hence demonstrating their efficacy in augmenting heat transfer.

The current study provides a comprehensive analysis of MHD hybrid nanofluids and stagnation point flow toward a porous stretched cylinder in the presence of thermal radiation. Here, alumina (Al₂O₃) and copper (Cu) are considered the hybrid nanoparticles, while water (H₂O) is the base fluid. To begin, the required similarity transformations are applied to transform the nonlinear coupled PDEs into nonlinear coupled ODEs. The obtained highly nonlinear sets of ODEs are then solved analytically by using the HAM procedure. The calculations of the thermal radiation term in the energy equation are done based on the Roseland approximation. The result of various embedded variables on temperature and velocity profiles is drawn and explained briefly. Aside from that, the numerical solution of well-known physical quantities, like skin friction and the Nusselt number, is computed by means of tables for the modification of the relevant parameter. The analysis shows that the magnetic field has opposite behavior on θ(η) and f'(η) profiles. It is seen that more magnetic factors M decline f'(η) and upsurge θ(η). Moreover, the behavior of skin friction and the Nusselt number are the same for the magnetic parameter M. Meanwhile, a higher Reynolds number R_e declines temperature profile and skin friction while upsurging the local Nusselt number. There are many applications of this study that are not limited to engineering and manufacturing, such as polymer industry, crystal growth, tumor therapy, plasma, fusing metal in electric heaters, nuclear reactors, asthma treatment, gastric medication, cooling of atomic systems, electrolytic biomedicine, helical coil heat exchangers, axial fan design, polymer industry, plane counter jets, and solar collectors.

In view of the large energy consumption of the regeneration process in the chemical absorption decarburization process, on the basis of the enrichment classification flow process, the nanoscale ceramic film is used as a new heat exchanger between the enriched liquid and the regeneration gas. The porous ceramic film is capable of coupling thermal-mass transfer to effectively recover part of the water vapor and the heat carried in the regeneration gas, so as to reduce the regenerative energy consumption of the system. The effects of parameters such as regeneration temperature, flow rate, molar fraction of water vapor, and MEA enrichment temperature, flow rate, and MEA concentration of shunt on the hydrothermal recovery effect of ceramic membranes of different pore sizes and lengths were studied by using the heat recovery flux and water recovery rate as the indicators. The results show that the hydrothermal recovery performance of the ceramic membrane increases with the increase of MEA enrichment flow, but decreases significantly with the increase of the enrichment temperature. At the same time, with the increase of regenerative gas velocity and the molar fraction of water vapor in the regenerative gas, the heat recovery flux will increase. The heat recovery performance of the 10 nm ceramic membrane is better than that of the 20 nm ceramic membrane.

The present article reports the applications of Caputo-Fabrizio time-fractional derivatives. This article generalizes the idea of unsteady MHD free convective flow in a Walters.-B fluid with heat and mass transfer study over an exponential isothermal vertical plate embedded in a porous medium. The governing equations are converted into dimensionless form and extended to fractional model. The generalized Walters-B fluid model has been solved analytically using the Laplace transform technique. From the general solutions we reduce limiting solutions when to the similar motion for Newtonian fluid. The corresponding expressions for and Nusselt and Sherwood numbers are also assessed. Numerical results for velocity, temperature and concentration are demonstrated graphically for various factors of interest and discussed. As a result, we have plotted the influence of fractional parameter on fluid flow and drawn comparison between fractional Walters’-B and fractional Newtonian fluid and found that fractional Newtonian fluid is faster than fractional Walters’-B fluids.