Electric Heating Device Research Articles

Design of the Energy-Saving Heater Based on Semiconductor Nano Electrothermal Film

The traditional electric heating device mainly used resistance wire as the electric vehicle components. A novel semiconductor nanoelectrothermal film as a heating material was to study its feasibility. By analyzing the heating mechanism of electrothermal film and comparing the existing heating device, an energy-saving heater was designed based on semiconductor nanoelectrothermal film. In STC89C52 micro-controller core, a practical and stable temperature control system was devised by a variety of control methods - shock control, relay control, pressure control, and so on. The energy consumption experiments were done between new electric heating device and conventional heater, and the results showed that new electric heating device had more energy efficient. On the basis of this study, a series of electric heating products could be developed with low power and environmental protection, and it was a useful exploration for technology upgrades for the electric heating industry.

Utilizing Thermoelectric Heat Pump to Heat Recovery of Shower Waste Water

The discharge of the shower wastewater is not only caused energy waste, but also caused a certain thermal pollution to the environment. The thermoelectric heat pump system, compared with the electric heating device, has a more effective output of heat energy. By recycling heat of shower wastewater, it can be both energy-saving and environmental. With a growing ratio of the energy consumption of hot water, the thermoelectric heat pump system may give us a new perspective in the area of waste heat recovery and energy efficiency in buildings.

Design and study of an electrical liquid heater using conductive polymer composite tubes

This study focuses on both the design and testing of an electrical heating device using current passage tubes made of Conductive Polymer Composites (CPC). To obtain such materials, an insulating polymer matrix is combined with electrical conductive fillers (carbon black, carbon fibres or metal particles). Power dissipation is observed when an electrical current is passed through the charged polymer matrix. To optimise heater design, two different axisymmetric, T(r,z) finite element models were developed with COMSOL®. The first model represents the electro-thermal behaviour of a current passage tube with internal water flow only. The second one takes into account water circulation both inside and outside the heating tube.A prototype was developed based on four immersed CPC tubes supplied electrically and hydraulically in parallel in a PVC casing. The experimental sequences performed on this pilot coupled with a hydraulic circuit made it possible to validate the two models. Analysis of the experimental recordings indicated that thermoelectric efficiency was higher than 90%. The thermal behaviour of such heaters was well defined on the basis of the information obtained from these tests and on the numerical simulations.

Experimental Inverstigation on Thermal Expansion Coefficients of SnO<sub>2</sub> Thin Film

As a kind of wide band-gap material focused on in recent years, SnO2 thin Film with μm level has been widely applied in many fields such as solar cells, electric heating devices, transparent electrodes, and gas sensors, ect. This paper develops a real-time system to measure thermal expansion coefficients of SnO2 thin film, which can obtain directly surface morphology information of the samples. Micro-imaging and digital image correlation method is adopted to investigate the correlation by comparing the object surface image before deformation with that after deformation. Because of the lower demand for measurement environment and no damage to object, it’s easy to acquire on-line images, calculate synchronously and display real-time results. In the paper, thermal expansion coefficients of SnO2 thin film are determined in situ with change of the temperature. Both of ceramic and SnO2 thin film have shown anisotropy thermal expansion, thermal and residual stress appears between the ceramic substrate and SnO2 thin film as a result of thermal expansion coefficients mismatch. According to experimental results, the maximum stress values can be calculated between film and substrate and inside the substrate.

A microwave reactor for characterization of pyrolyzed biomass

A microwave reactor (MWR) was designed to investigate microwave-induced pyrolysis of biomass. Condensation of tars on the quartz reactor and the pipelines was prevented by an electric heating device, and a temperature control function allowed determination of product characteristics at constant temperatures. Temperature had an important influence on microwave pyrolysis; the yields of gas products increased from 17.69wt.% to 22.27wt.% and the ratio of combustible gas to total gas products increased from 67.21vol.% to 77.14vol.% as the temperature increased from 400°C to 600°C. A large number of volatiles was released as temperature increased, resulting in an increase in the number of pores of the coke and a uniform pore structure was obtained. The specific surface area of coke increased from 0.89m2/g (400°C) to 9.81m2/g (600°C) and the pore volume increased from 0.006cm3/g (400°C) to 0.012cm3/g (600°C), but the average pore size decreased from 282.16nm (400°C) to 46.64nm (600°C).

Influence of glass frits on working properties of kaolins

This paper presents a report of the effects of glass frits on the properties of some Nigerian clays. Eight test pieces of various compositions with 10, 20, 30, up to 80% glass frit addition were prepared and analyzed. The samples were tested for properties such as cold crushing strength, linear shrinkage, fusion point and loss on ignition. The samples with 50% glass frits showed optimum strength and lowest shrinkage. The minimum strength was obtained from the sample with 80% glass frit. The optimal operating temperature for all the samples was 1000 °C. Thus Nigerian clays reinforced with appropriate quantities of glass frits are suitable for different low temperature applications such as in electrical heating devices, vitrified tiles and tablewares.

Numerical and analytical modelling of entropy noise in a supersonic nozzle with a shock

Analytical and numerical assessments of the indirect noise generated through a nozzle are presented. The configuration corresponds to an experiment achieved at DLR by Bake et al. [The entropy wave generator (EWG): a reference case on entropy noise, Journal of Sound and Vibration 326 (2009) 574–598] where an entropy wave is generated upstream of a nozzle by an electrical heating device. Both 3-D and 2-D axisymmetric simulations are performed to demonstrate that the experiment is mostly driven by linear acoustic phenomena, including pressure wave reflection at the outlet and entropy-to-acoustic conversion in the accelerated regions. Moreover, the spatial inhomogeneity of the upstream entropy fluctuation has no visible effect for the investigated frequency range (0–100 Hz). Similar results are obtained with a purely analytical method based on the compact nozzle approximation of Marble and Candel [Acoustic disturbances from gas nonuniformities convected through a nozzle, Journal of Sound and Vibration 55 (1977) 225–243] demonstrating that the DLR results can be reproduced simply on the basis of a low-frequency compact-elements approximation. Like in the present simulations, the analytical method shows that the acoustic impedance downstream of the nozzle must be accounted for to properly recover the experimental pressure signal. The analytical method can also be used to optimize the experimental parameters and avoid the interaction between transmitted and reflected waves.

Thermal–electric numerical simulation of a target for the production of radioactive ion beams

The production target is the core of the facilities aimed at the production of Radioactive Ion Beams. In the facility analysed in this paper, a proton beam directly impinges a target made of uranium carbide that generates the radioactive isotopes needed to produce Radioactive Ion Beams. To work properly, the target has to maintain the average temperature of two thousands Celsius degrees, but the proton beam power is not sufficient to maintain this temperature level; as a consequence an electric heating device has to be added. In this work the production target and its heating system are analysed by means of both analytic and numerical thermal–electric models. In particular, the numerical model was implemented by means of a commercial finite element code and fully coupled thermal–electric analyses were performed with a proper solution method for the radiative heat transfer problem. Theoretical results have been compared with experimental data in terms of temperature and electric potential difference, showing the substantial reliability of both the analytic and the numerical models. Subsequent to the validation of the finite element model, a sensitivity analysis was performed to investigate the influence of some design variables and construction details on the target temperature distribution.

Topochemical investigation into the delignification of Eucalyptus globulus chips during semi-chemical sulfite pulping

The course of delignification of Eucalyptus globulus fibers during neutral semi-chemical sulfite pulping (NSSC) was studied by universal microspectrophotometry (UMSP 80, ZEISS). UV-investigation into a cellular level enables the topochemical analyses of delignification within individual cell wall layers during cooking. Cooks were carried out in a laboratory seven liter digester with liquor circulation and electrical heating device. Chip samples were taken throughout the cooking for chemical and UV microscopic analyses. UV microscopy analysis revealed for Eucalyptus globulus chips a preferred lignin removal during NSSC cooking in cell corner and compound middle lamella regions.

Exposure assessment and risk characterisation for consumers associated to the use of electrical diffuser for insecticides

Insecticides are mainly used in the home environment, and most of them are recognised to pose risks for the human health. In particular, pyrethroids are an insecticide category widely used in agriculture and households, and for industrial purposes to get protection from mosquitoes, cockroaches and other insects. In this study, both exposure and risk following the application of insecticides by using an electrical heating device have been characterised. The indoor exposure levels have been estimated by using ConsExpo Model. The exposure values have been compared with the toxicological data from the WHO Specifications. Thus, the risks have been estimated by calculating the Derived No-Effect Level (DNEL) and the risks result to be very low. However, a potential risk might occur at the beginning of the exposure. Therefore, possible risk reduction measures should be put in place, such as avoiding people to stay while the electrical heating device is functioning.

Numerical and analytical investigation of the indirect combustion noise in a nozzle

Analytical and numerical assessments of the indirect noise generated through a nozzle are presented. The configuration corresponds to an experimental setup operated at DLR by Bake et al. (2008) where an entropy wave is generated upstream of the nozzle by means of an electrical heating device. Both 3-D and 2-D axisymmetric simulations are performed to demonstrate that the experiment is mostly driven by linear acoustic phenomena, including pressure wave reflection at the outlet and entropy-to-acoustic conversion in the accelerated regions. Results show that the acoustic impedance downstream of the nozzle must be accounted for appropriately in order to recover the experimental pressure signal. A good agreement is also obtained with a purely analytical assessment based on the Marble and Candel compact nozzle approximation. To cite this article: M. Leyko et al., C. R. Mecanique 337 (2009).

Synthesis of Urea-Nitryle-Urethanes with Aid of Microwaves

Polymerisation of urea-nitryle-urethanes performed in electric heating devices. It was suggested to manufacture these materials using microwave radiation as the heat source. As a part of this research project urea urethanes were fabricated using various strength of microwave radiation. The structure and properties of manufactured materials were investigated.

A new heat recovery technique for air-conditioning/heat-pump system

A new heat recovery technique for an air-conditioning/heat-pump (AC/HP) system is proposed in this paper. The new technique employs a compound air-cooling and water-cooling condensing module to replace the traditional sole air-cooling condensing module of the AC/HP system. The system adopting this technique can be called a multi-function AC/HP system. It can improve cooling and heating effects, and recover condensing heat for heating sanitary water. A fluid bypass pneumatic controlled reversing valve is also added to the system. It makes sure that the system can shift flexibly between different working modes according to the building users’ requirement. An experimental unit of the new technique AC/HP system has been made and tested. Testing results indicate that the new AC/HP system is able to perform stably and flexibly under various conditions. The system has relatively large coefficient of performance (COP) which can be as high as about 6.0. It is suggested that a supplementary electric heating device should be used to heat water to a higher temperature in the winter before starting sanitary water.

Development of Thermoelectric Heat Pump Water Heaters

Experiments verified that a thermoelectric heat pump system is more efficient than an electrical heating device, for its heating coefficient reached more than 1.6 with suitable operating conditions. Two novel instantaneous water heaters were developed and tested successively. The prototype with circulating water pump can save power consumption more than 40% in comparison with conventional electric water heaters, while the prototype integrating with thermosiphon can save more than 38%. Comparing two prototypes, the latter prototype becomes more compact, more technologically advanced and practical, because it eliminated the working life choke-point of the former, while holding the advantages, such as high efficiency, reliability, safety, environmental friendly.

A novel water heater integrating thermoelectric heat pump with separating thermosiphon

Experiments verified that a thermoelectric heat pump system is more efficient than an electrical heating device, for its heating coefficient reached more than 1.6 with suitable operating conditions. On the base of experimental data, a novel instantaneous water heater was developed by means of integrating thermoelectric (TE) heat pump with separating thermosiphon. The original flow path of the prototype facilitated heat recovering from drainage, and remarkably reduced the temperature difference between heat sink and source of the TE heat pump, thus its performance is improved greatly. Performance tests illustrated that the prototype can save more than 38% of the power consumption compared with that of conventional electric water heaters. It is of great practical interest in building energy saving, supplying hot water for carriages, ships and other analogous movable spaces.

Residential load modeling for predicting distribution transformer load behavior, feeder load and cold load pickup

This paper presents a physically based model for computing the electric load on residential distribution feeders and on distribution transformers. The load is assumed to consist of electric space heating, electric water heating and other miscellaneous devices. Validation against field tests and field monitoring records shows the accuracy of the approach both for steady-state operation and for power restoration conditions. The magnitude and duration of cold load pickup is predicted more accurately with the approach presented than with previous models.

Improved Start-Up for the Ammonia Oxidation Reaction

The start-up operation in a nitric acid plant is one of the most important stages, from the viewpoint of safety and platinum loss, in the entire ammonia oxidation process. Usually, flame burners using hydrogen or hydrogen-containing gas preheat the platinum alloy gauze catalyst to the operating temperature. However, there are disadvantages and peculiarities in this method of initiating the start-up reaction. These are discussed here and a new electrical heating device and a new technique are described for preheating the platinum alloy gauze catalyst. The device and technique are free of these disadvantages, and together they reduce the explosive hazard and platinum losses during start-up. Results from their commercial utilisation over a 12-year period at various nitric acid plants are described.

An energy-saving method of heating for a chemomechanical poly( N-isopropylacrylamide) gel with Joule's heat

Macroporous poly( N-isopropylacrylamide) gel, swollen in NaCl solution, showed electric conductivity inside the gel. Swollen gel could be heated electrically by the application of AC voltage (100 V, 50 Hz) through the inserted electrodes within both ends of the gel rod. Joule's heat generated inside the gel was effective in bringing about a phase transition of gel. The gel swollen in 0.5 M NaCl solution at 22°C could generate the contractile stress with increasing temperature of gel after applying AC voltage. The deswelling rate and the maximum stress generated were 1.3 kPa s −1 and 8.0 kPa, respectively. The device of a bundle of 5 gel rods ( = 1.5 mm) could lift the weight (10 kPa as tensile strength) within 20 s, and work mechanically faster than the device of magnetic heating reported in our previous paper. The electric heating device gel could save more energy by reducing heat loss due to radiation.

Operation of a catalytic reverse flow reactor for the purification of air contaminated with volatile organic compounds

AbstractCatalytic oxidation in a reverse flow reactor is an attractive process for the decontamination of air polluted with volatile organic compounds (VOCs). In this paper several aspects of operating this type of reactor for air purification under strongly varying conditions will be discussed.For a successfit operation of such reactor a minimum amount of combustibles is required, and a simple theory is developed to predict this minimum value. This minimum amount is strongly influenced by the reaction kinetics, the heat transport in the packed bed and the adiabaticity of the reactor. To cope with a too low temperature level in the reactor for a complete conversion, an electrical heating device should be installed in the centre of the reactor bed to increase locally the temperature rapidly and efficiently. To control the maximum temperature in case of too high concentrations, extra air should be added to the feed.

Is space heating in offices really necessary?

New office buildings in Sweden are thoroughly insulated due to the Swedish building code. This code, however, does not consider the type of activity occurring in the building. This means that the heating equipment is designed as if no activity at all is going on. In modern offices there is a lot of equipment installed which uses electricity. This electricity is converted into heat which can be utilized for heating the premises, mostly in a direct way but also by the use of exhaust-air heat-pumps or heat exchangers. This paper deals with a modern office building plus office hotel complex located in Linköping, Sweden, about 200 km south of Stockholm. The tenants deal with the design of hard- and software for computers. The lighting and computers in the building use electricity which converts into heat. In this paper, it is shown that this electricity is all that is needed during normal conditions, i.e. when people work in the building. The building is also equipped with a district-heating system, which is designed as if no activity goes on in the building, so subsequently the heating equipment is larger than it need be. In this special case, it might have been better to install an electric heating device for hot-water heating and very cold winter conditions, instead of using district heating. This is so even if district heat is about half the unit price compared with that due to the dissipation of electricity. At present, when district heating is used, no measures for saving heat can be profitable due to the low district-heating price. The fact is that the tenants complain of too much heat instead of too little: the prevailing indoor temperature was about 24° C in January 1990 even though 20° C would have been sufficient. There is subsequently a need for a properly working regulation system. The one currently in use is designed to a modern standard, but is not able to maintain temperatures at a modest level.