Liquid Heating System Research Articles

Design of a packed bed chemical looping (unmixed) combustion reactor for the application of heating liquid: A theoretical study

AbstractA packed bed reactor (PBR)‐based chemical looping combustion (CLC), also referred to as unmixed combustion (UMC), was reported as an alternative to fire in the literature. In this process, the oxygen carriers undergo oxidation and reduction reactions in alternate cycles using air and fuel as the reactive gases, respectively. The energy generated in these reactions can radially be transferred for applications like heating air which was successfully demonstrated. The results showed that 85–95% of the generated energy can radially be transferred while maintaining sustained combustion in the bed (at temperatures between 723 and 1173 K). While extending its application for heating liquids like water, it was found in the modeling and simulation study that the existing design resulted in quenching of the bed below 773 K in the oxidation cycle and achieving sustained combustion was not possible for all practical ranges of operating parameters. Hence it was decided to modify the existing system by increasing the volume ratio of the annular bed to the liquid section. Theoretical estimations revealed that increasing this ratio by four times or higher can result in maintaining sustained combustion conditions in the bed while having continuous radial heat transfer to the water flowing in the laminar range. The general guidelines for designing a UMC‐based liquid heating system were then prepared and used to propose a new design for water heating. The modeling and simulation studies for this proposed design also indicated that it is a feasible design. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Small-Sized Immersible Water Heaters for Domestic Induction Heating Technology

Induction cooktops are a key element in home electrification. This paper presents a new use of induction cooktops, which allows the preparation of infusions directly in a ceramic mug. It is proposed the design of a water heater with an immersible metallic load. The dimensions of the load allow its embedding in small ceramic vessels. Despite being smaller than conventional inductors, the immersible load has a specific shape that allows it to efficiently receive the energy from the induction cooktops and quickly heat the liquid inside the mug. Its geometry consists of a flat disk with sidewalls on its edge, which provides low reluctance paths for the magnetic field, resulting in improved transmitted power and efficiency. The load is arranged in a multilayer structure consisting of a ferromagnetic alloy with low Curie temperature at the bottom and aluminum on the top, which confers self-detection capabilities against dangerous overheating. The study of the proposal has been carried out with a finite element analysis model, and the feasibility of this proposal has been demonstrated through experimental results of its performance. Finally, the immersible water heater, powered by an induction cooktop, has been compared to other liquid heating systems, such as the microwave and the kettle, with promising results.

Large Eddy Simulation and Thermodynamic Design of the Organic Rankine Cycle Based on Butane Working Fluid and the High-Boiling-Point Phenyl Naphthalene Liquid Heating System

Large Eddy Simulation (LES) and Thermodynamic study have been performed on Organic Rankine Cycle (ORC) components (boiler, evaporator, turbine, pump, and condenser). The petroleum Coke burner provided the heat flux needed for the butane evaporator. High boiling point fluid (called phenyl-naphthalene) has been applied in the ORC. The high boiling liquid is safer (steam explosion hazard may be prevented) for heating the butane stream. It has best exergy efficiency. It is non-corrosive, highly stable, and flammable. Fire Dynamics Simulator software (FDS) has been applied in order to simulate the pet-coke combustion and calculate the Heat Release Rate (HRR). The maximal temperature of the 2-Phenylnaphthalene flowing in the boiler is much less than its boiling temperature (600 K). Enthalpy, entropy and specific volume required for evaluating the heat rates and the power have been computed by employing the THERMOPTIM thermodynamic code. The proposed design ORC is safer. This is because the flammable butane is separated from the flame produced in the petroleum coke burner. The proposed ORC obeys the two fundamental laws of thermodynamics. The calculated net power is 3260 kW. It is in good agreement with net power is reported in the literature. The thermal efficiency of the ORC is 18.0%.

Novel electromagnetic-black-hole-based high-efficiency single-mode microwave liquid-phase food heating system

Microwave heating exhibits a high potential for usage in liquid food processing. Current microwave heating systems are designed for a specific load. However, when the permittivity of the load changes dynamically, the heating efficiency of these systems fluctuates considerably. We proposed a novel high-efficiency microwave liquid heating system for dynamic dielectric loads to address this limitation. In this system, an electromagnetic black hole efficiently absorbs electromagnetic waves in all directions. First, an electromagnetic black hole was realized using metamaterials (which means artificially structured dielectric materials with extraordinary physical properties) with a radially continuous refractive index distribution. Next, an electromagnetic field simulation model was established to calculate the microwave absorption of various load permittivity. To discretize and simplify the parameters of the continuous distribution in an electromagnetic black hole, a concentric layered structure and a punched structure composed of uniform isotropic dielectric materials were designed. Finally, the experimental samples were processed based on the two discrete structures. The microwave system developed for experimental verification confirmed the high efficiency of the heating system; the system is simple and usable in numerous applications. Thus, the proposed method can realize high-efficiency heating of loads over large dielectric dynamic ranges. When the dielectric constant of the load changed dynamically from 10 to 80, the microwave energy utilization rate can increase by up to 90%.

Research on thermal equilibrium performance of liquid-cooled lithium-ion power battery system at low temperature

The development of electric vehicles is an important trend in the automotive industry, in which the performance of power batteries is greatly affected by temperature. In recent years, it has been widely concerned that the performance of power batteries at low temperature will lead to the vehicle failure to start because of the bad thermal equilibrium of power battery heating system. This paper studies the thermal equilibrium performance of battery liquid heating system at low temperature. Inlet temperature, heating time, ambient temperature, and their coupling relationship to battery thermal equilibrium performance are studied by orthogonal experimental design method. It is expected that this study can provide reference for the parameter selection of battery heating system.

Non-adiabatic annular flow experiments in a subchannel geometry with spacer grid

Boiling annular flow in a subchannel geometry with functional spacers is studied using X-Ray tomography in the Dryout Tomography Experiment (DoToX) facility at ETH Zürich. The liquid film distribution on the walls and the liquid holdup within the gas core of the annular flow in the subchannel, both under the influence of the spacer vanes, are extracted from tomographic images. The subchannel cross section consists of a main subchannel in the center surrounded by four heating flow sections representing fuel rods and connected to four partial subchannels with simplified geometry. This effectively removes unnatural no-slip boundary conditions at the narrow gap of the main subchannel.Chloroform is used as a working fluid because of its low enthalpy of evaporation and a low boiling point around 60 °C close to atmospheric pressure. A liquid heating system with water at slightly above 100 °C provides the heating power for the boiling process. This ensures continuous operation of the facility even in case of a dryout scenario, avoiding structural damages by imposing a maximum system temperature. The high thermal capacity of the water allows for an almost isothermal boundary condition. Although not identical to real BWR settings, this experiment is well suited to generate data for model validation.Originally designed for tomographic imaging with both cold neutrons and X-rays, this paper focuses on results obtained by X-rays. Since the X-ray contrast between the working fluid chloroform and the structural material of the channel, aluminum, is very small, differential imaging with adaptive centering of reconstructions with and without the liquid film were required. The measurement campaign consisted of three measurements with constant chloroform mass flows at 5.00, 4.05 and 3.25 kg/min and constant heating liquid temperature of 100–104 °C, in addition to the empty channel reference measurement. The thermal power transferred to the working fluid under these conditions was about 10 kW of heating power. The resulting liquid film thicknesses (LFT) upstream of the spacer decreased from 91 to 49 µm. The effect of the spacer vanes is visualized and quantified over an axial section of 10 hydraulic diameters. Reference samples of the film thickness and the liquid holdup were taken upstream of the spacer. Dryout was nearly reached in characteristic regions of reduced film thickness due to turbulent shear stresses, while other regions show a significant local increase of the liquid film thickness. The deposition of about 30% of the liquid holdup from the gas core contributes to the increase. The results are consistent with previous adiabatic experiments with similar geometries.

An Optimized Energy Management Strategy for Preheating Vehicle-Mounted Li-ion Batteries at Subzero Temperatures

This paper presents an optimized energy management strategy for Li-ion power batteries used on electric vehicles (EVs) at low temperatures. In low-temperature environments, EVs suffer a sharp driving range loss resulting from the energy and power capability reduction of the battery. Simultaneously, because of Li plating, battery degradation becomes an increasing concern as the temperature drops. All these factors could greatly increase the total vehicle operation cost. Prior to battery charging and vehicle operating, preheating the battery to a battery-friendly temperature is an approach to promote energy utilization and reduce total cost. Based on the proposed LiFePO4 battery model, the total vehicle operation cost under certain driving cycles is quantified in the present paper. Then, given a certain ambient temperature, a target preheating temperature is optimized under the principle of minimizing total cost. As for the preheating method, a liquid heating system is also implemented on an electric bus. Simulation results show that the preheating process becomes increasingly necessary with decreasing ambient temperature, however, the preheating demand declines as driving range grows. Vehicle tests verify that the preheating management strategy proposed in this paper is able to save on total vehicle operation costs.

Neuro-fuzzy-based hybrid controller for stable temperature of liquid in heat exchanger

The liquid heating system is a temperature sustaining system which used to preserve the liquid temperature at a constant value at different temperature ranges. In this paper, neuro-fuzzy controller (NFC)-based control technique is proposed for achieving the desired liquid temperature. NFC is the combination of neural network (NN)-based controller and fuzzy logic controller (FLC). Initially, the error temperature and change of error temperature of a liquid heating system are determined. Then, the temperature variation is applied separately to FLC and NN-based controller. From the output of FLC and NN-based controller, the mean liquid temperature ratio of the condenser is calculated. Then based on the liquid temperature ratio, the automatic control valve (ACV) is adjusted till the desired temperature is reached. The proposed system is modelled in simulation platform and the output performances are evaluated. Then, the temperature stabilising performance of proposed controller is compared with FLC and ANN.

Evacuated Tube Collectors - Influence of thermophysical properties in numerical simulations by CFD

Solar liquid heating systems using evacuated tube collectors currently have a better performance than flat plate collectors for high temperature operation. This is due to reduced heat losses by convection, as a result of the vacuum layer over the inner tube. The solar collectors with vacuum tubes are a novelty in Brazil, in addition, its use on a commercial scale is less than 10 years and there are many questions to be answered about their use and efficiency. To get a better understanding of the operation of this equipment, it has started a program of study through a collaboration between the NETE - UNISINOS (Study Center Thermal and Energy of University of Vale do Rio dos Sinos) and LABSOL-UFRGS (Solar Energy Laboratory of Federal University of Rio Grande do Sul). The methodology consists in the numerical simulation by CFD (Computer Fluid Dynamics) and validate the methodology through numerical and experimental results. The results of velocity fields and mean temperature indicate that the methodology is quite adequate.

Design and Numerical Simulation of a Symbiotic Thermoelectric Power Generation System Fed by a Low-Grade Heat Source

All liquid heating systems, including solar thermal collectors and fossil-fueled heaters, are designed to convert low-temperature liquid to high-temperature liquid. In the presence of low- and high-temperature fluids, temperature differences can be created across thermoelectric devices to produce electricity so that the heat dissipated from the hot side of a thermoelectric device will be absorbed by the cold liquid and this preheated liquid enters the heating cycle and increases the efficiency of the heater. Consequently, because of the avoidance of waste heat on the thermoelectric hot side, the efficiency of heat-to-electricity conversion with this configuration is better than that of conventional thermoelectric power generation systems. This research aims to design and analyze a thermoelectric power generation system based on the concept described above and using a low-grade heat source. This system may be used to generate electricity either in direct conjunction with any renewable energy source which produces hot water (solar thermal collectors) or using waste hot water from industry. The concept of this system is designated “ELEGANT,” an acronym from “Efficient Liquid-based Electricity Generation Apparatus iNside Thermoelectrics.” The first design of ELEGANT comprised three rectangular aluminum channels, used to conduct warm and cold fluids over the surfaces of several commercially available thermoelectric generator (TEG) modules sandwiched between the channels. In this study, an ELEGANT with 24 TEG modules, referred to as ELEGANT-24, has been designed. Twenty-four modules was the best match to the specific geometry of the proposed ELEGANT. The thermoelectric modules in ELEGANT-24 were electrically connected in series, and the maximum output power was modeled. A numerical model has been developed, which provides steady-state forecasts of the electrical output of ELEGANT-24 for different inlet fluid temperatures.