Experimental design and numerical validation of a low-cost water heater by electromagnetic induction

This study shows a new approach to heat water in a residential environment. An electromagnetic heating method is proposed. A steel bar inside a pipeline filled with water is heated by five arrangements of a copper coil which incites the steel bar by electromagnetic induction. Consequently, numerical simulation and experimental evaluation are compared. The outcomes evaluated two different scenarios: steady water and a water flow of 0.16 kg/s. Three rods demonstrated that current induction of 20 A at the surface of the steel bar heats at 157°C. Also, the maximum value reached is 58°C. Heating the water upon for those conditions, the proposed tankless instantaneous water heater (TIWH) reaches a temperature of 41.01°C with one rod but only reaches 37.92°C with three rods in a series configuration, in a parallel configuration, the maximum temperature reached was 28.73°C.

Recent Advances and Challenges in the Development of Radiofrequency HTS Coil for MRI

Radiofrequency (RF) coils fashioned from high-temperature superconductor (HTS) have the potential to increase the sensitivity of the magnetic resonance imaging (MRI) experiment by more than a dozen times compared to conventional copper coils. Progress, however, has been slow due to a series of technological hurdles. In this article, we present the developments that recently led to new perspectives for HTS coil in MRI, and challenges that still need to be solved. First, we recall the motivations for the implementations of HTS coils in MRI by presenting the limits of cooled copper coil technology, such as the anomalous skin effect limiting the decrease of the electric resistance of normal conductors at low temperature. Then, we address the progress made in the development of MRI compatible cryostats. New commercially available low-noise pulsed-tube cryocoolers and new materials removed the need for liquid nitrogen-based systems, allowing the design of cryogen-free and more user-friendly cryostats. Another recent advance was the understanding of how to mitigate the imaging artifacts induced by HTS diamagnetism through field cooling or temperature control of the HTS coil. Furthermore, artifacts can also originate from the RF field coupling between the transmission coil and the HTS reception coil. Here, we present the results of an experiment implementing a decoupling strategy exploiting nonlinearities in the electric response of HTS materials. Finally, we discuss the potential applications of HTS coils in bio-imaging and its prospects for further improvements. These include making the technology more user-friendly, implementing the HTS coils as coil arrays, and proposing solutions for the ongoing issue of decoupling. HTS coil still faces several challenges ahead, but the significant increase in sensitivity it offers lends it the prospect of being ultimately disruptive.

Modeling on the Effect of Heat Exchanger Submersion on Controlling Spontaneous Combustion in A Coal Pile

Spontaneous combustion of coal has been well-known as a problem faced by coal industries, especially in storing and trans-shipping processes. The negative impacts of this phenomenon have led to several hazardous incidents and degrading product quality. Several methods have been researched to minimize the impacts; one of the proposed ways is immersing heat exchangers inside the coal stockpile. An experiment was conducted to analyze the cooling effect of an immersed simple heat exchanger made of a copper coil. By varying the number of windings, the experiment showed a significant decrease in pile temperature due to the immersed heat exchanger. This work continues exploring the possibility of applying the method by observing and analyzing the simulation model. COMSOL Multiphysics was used to model the physics phenomena that occur within the coal reactor. The effect of the heat exchanger surface area was studied from the model to observe the heat propagation within the coal reactor. The vast reach of heat propagation from the heat exchanger through the coal pile on the simulation was promisingly showing that this method was useful to limit the occurrence of spontaneous fire in coal piles.

LTspice Electro-Thermal Model of Joule Heating in High Density Polyethylene Optical Fiber Microducts

At present, optical fiber microducts are joined together by mechanical type joints. Mechanical joints are bulky, require more space in multiple duct installations, and have poor water sealing capability. Optical fiber microducts are made of high-density polyethylene which is considered best for welding by remelting. Mechanical joints can be replaced with welded joints if the outer surface layer of the optical fiber microduct is remelted within one second and without thermal damage to the inner surface of the optical fiber duct. To fulfill these requirements, an electro-thermal model of Joule heat generation using a copper coil and heat propagation inside different layers of optical fiber microducts was developed and validated. The electro-thermal model is based on electro-thermal analogy that uses the electrical equivalent to thermal parameters. Depending upon the geometric shape and material properties of the high-density polyethylene, low-density polyethylene, and copper coil, the thermal resistance and thermal capacitance values were calculated and connected to the Cauer RC-ladder configuration. The power input to Joule heating coil and thermal convection resistance to surrounding air were also calculated and modelled. The calculated thermal model was then simulated in LTspice, and real measurements with 50 µm K-type thermocouples were conducted to check the validity of the model. Due to the non-linear transient thermal behavior of polyethylene and variations in the convection resistance values, the calculated thermal model was then optimized for best curve fitting. Optimizations were conducted for convection resistance and the power input model only. The calculated thermal parameters of the polyethylene layers were kept intact to preserve the thermal model to physical structure relationship. Simulation of the optimized electro-thermal model and actual measurements showed to be in good agreement.

Modular Toroidal Copper Coil for the Investigation of Inductive Pulsed Power Generators in the MJ-Range

<div>Poster contribution to the 26th International Conference on Magnet Technology (MT26) in Vancouver, Canada, September 22-27, 2019. paper was submitted to the MT26 special issue of the IEEE Transactions on Applied Superconductivity.</div><div><br></div><div>Abstract: Inductive pulsed power generators apply coils as<br>powerful short time energy storage which is an ordinary mean to deliver pulses of high power to loads like electromagnetic accelerators. This article deals with the design, simulation, construction, electrical characterization and a pulsed stress test of a modular toroidal coil. The coil was made from 180 D-shaped copper discs and has an approximate inductance of 1mH (f > 50 Hz) and frequency dependent resistance according to 3.88 mOhm Sqrt(f) + 5 mOhm. Its height, diameter and weight is 0.4 m, 1 m and 1 ton respectively. It is designed to store more than 1 MJ<br>of energy.<br></div>

Modular Toroidal Copper Coil for the Investigation of Inductive Pulsed Power Generators in the MJ-Range

<div>Poster contribution to the 26th International Conference on Magnet Technology (MT26) in Vancouver, Canada, September 22-27, 2019. paper was submitted to the MT26 special issue of the IEEE Transactions on Applied Superconductivity.</div><div><br></div><div>Abstract: Inductive pulsed power generators apply coils as<br>powerful short time energy storage which is an ordinary mean to deliver pulses of high power to loads like electromagnetic accelerators. This article deals with the design, simulation, construction, electrical characterization and a pulsed stress test of a modular toroidal coil. The coil was made from 180 D-shaped copper discs and has an approximate inductance of 1mH (f > 50 Hz) and frequency dependent resistance according to 3.88 mOhm Sqrt(f) + 5 mOhm. Its height, diameter and weight is 0.4 m, 1 m and 1 ton respectively. It is designed to store more than 1 MJ<br>of energy.<br></div>