scholarly journals Calculation of substitution scheme parameters inductive-conductive heater

2021 ◽  
pp. 7-16
Author(s):  
Anatoly Elshin ◽  
◽  
Vyacheslav Kozhukhov ◽  
Petr Elshin ◽  
◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Equivalent Circuit ◽  
Operating Conditions ◽  
Hot Water ◽  
Production Costs ◽  
Water Supply Systems ◽  
Stationary Mode ◽  
Secondary Circuit ◽  
Preliminary Calculation ◽  
Heating Chamber

To reduce production costs in the design and creation of an inductive-conductive heater (ICH), it is necessary to carry out a preliminary calculation as accurately as possible. This is possible when using the most approximate electrical circuit for replacing the ICH to a real object. It becomes possible to assess the work of the ICH in various operating conditions, including emergency conditions, using simpler modeling. An inductive-conductive heater transformertype is a three-rod W-shaped magnetic circuit with primary windings, which are covered by a heat exchanger (HE) of three concentric systems of electrically conductive cylinders with an internal slotted channel for the coolant. The energy from the mains supply is inductively transferred to the heat exchanger through the air gap by means of the primary winding. The secondary circuit of an electromagnetic device is a heat exchanger in which electrical energy is converted into heat. The heat flux from the heated cylindrical walls of the HE conductively heats the coolant circulating in the system to the required temperature. The large surface area of the HE allows you to avoid its overheating in relation to the coolant, which has a positive effect during the operation of the ICH in heating and hot water supply systems, significantly reducing the deposition of water impurities on the walls of the HE. The service life of the device is increased to 100 thousand hours or more. In the work, the synthesis of elements of the ICH equivalent circuit is carried out and the results of calculating the characteristics of the stationary mode of a number of products are presented. The equivalent circuit allows you to simulate electromagnetic processes in devices of different power, voltage and industrial frequencies in the range of 50…1000 Hz. If the configuration of the heating chamber (secondary circuit) is changed, the parameters of the elements of the equivalent circuit are adjusted without changing the general construction algorithm. For new products of inductive-conductive heating, there are no bibliographic data for calculating the elements of the equivalent circuit, especially regarding the formation of the replacement circuit of the secondary circuit, determined by the design of the heating chamber. To fill this gap, the authors have done this work.

Cogeneration System Modeling Based on Experimental Results

2010 ◽  
Author(s):  
Flore Marion ◽  
Fred Betz ◽  
David Archer
Keyword(s):  
Heat Exchanger ◽  
Steam Generator ◽  
System Modeling ◽  
Primary Component ◽  
Performance Model ◽  
Operating Conditions ◽  
Hot Water ◽  
Plant Design ◽  
Absorption Chiller ◽  
Cogeneration System

A 25 kWe cogeneration system has been installed by the School of Architecture of Carnegie Mellon University that provides steam and hot water to its Intelligent Workplace, the IW. This cogeneration system comprises a biodiesel fueled engine generator, a steam generator that operates on its exhaust, a hot water heat exchanger that operates on its engine coolant, and a steam driven absorption chiller. The steam and hot water are thus used for cooling, heating, and ventilation air dehumidification in the IW. This cogeneration system is a primary component of an overall energy supply system that halves the consumption of primary energy required to operate the IW. This cogeneration system was completed in September 2007, and extensive tests have been carried out on its performance over a broad range of power and heat outputs with Diesel and biodiesel fuels. In parallel, a detailed systems performance model of the engine generator, its heat recovery exchangers, the steam driven absorption chiller, a ventilation and air dehumidification unit, and multiple fan coil cooling/heating units has been programmed making use of TRNSYS to evaluate the utilization of the heat from the unit in the IW. In this model the distribution of heat from the engine to the exhaust, to the coolant, and directly to the surroundings has been based on an ASHRAE model. While a computational model was created, its complexity made calculation of annual performance excessively time consuming and a simplified model based on experimental data was created. The testing of the cogeneration system at 6, 12, 18 and 25 kWe is now completed and a wealth of data on flow rates, temperatures, pressures throughout the system were collected. These data have been organized in look up tables to create a simplified empirical TRNSYS component for the cogeneration system in order to allow representative evaluation of annual performance of the system for three different mode of operation. Using the look up table, a simple TRNSYS module for the cogeneration system was developed that equates fuel flow to electricity generation, hot water generation via the coolant heat exchanger, and steam production via the steam generator. The different modes of operation for this cogeneration system can be design load: 25 kWe, following the thermal — heating or cooling — load, following the ventilation regeneration load. The calculated annual efficiency for the different mode is respectively 66% 68% and 65%. This cogeneration installation was sized to provide guidance on future cogeneration plant design for small commercial buildings. The new cogeneration TRNSYS component has been created to be applicable in the design of various buildings where a similar cogeneration system could be implemented. It will assist in selection of equipment and of operating conditions to realize an efficient and economic cogeneration system.

A Transient Immersed Coil Heat Exchanger Model

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
William R. Logie ◽  
Elimar Frank
Keyword(s):  
Heat Exchanger ◽  
Water System ◽  
Operating Conditions ◽  
Hot Water ◽  
Simulation Environment ◽  
One Dimensional ◽  
Solar Fraction ◽  
Coil Heat Exchanger ◽  
Side Flow ◽  
Coil Heat

The aim of this paper is to present a transient one-dimensional (1D) radial immersed coil heat exchanger model that accounts for the effect that geometry and operating conditions have on heat transfer performance. Insights gained through its use in both an analysis of experimental data and an implementation in the simulation environment TRNSYS are shown and discussed. While variation in the external convection coefficient of immersed coil heat exchangers has little effect on the annual solar fraction of a generic solar domestic hot water system, variation in collector side flow can influence the solar fraction as great as ±5%, in particular low collector side flow improves stratification inside the store.

scholarly journals An Investigation on the Effect of the Total Efficiency of Water and Air Used Together as a Working Fluid in the Photovoltaic Thermal Systems

Processes ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 516 ◽  
Author(s):  
Mustafa Atmaca ◽  
İmdat Zafer Pektemir
Keyword(s):  
Heat Exchanger ◽  
Climatic Conditions ◽  
Hot Water ◽  
Working Fluid ◽  
Photovoltaic Module ◽  
Water Supply Systems ◽  
Total Efficiency ◽  
Electrical Efficiency ◽  
Pv Panel ◽  
T System

The temperature of a PV (photovoltaic) panel increases when it produces electricity but its electrical efficiency decreases when the temperature increases. In addition, the electrical efficiency of the PV panel is very limited. To increase the PV efficiency, the rest of the solar irradiance must be used, together with the temperature being kept at an optimum value. With this purpose, an experimental study was conducted. Firstly, two specific photovoltaic-thermal (PV/T) systems were designed. The first was the PV/T system which used only a water heat exchanger. The other one was the PV/T system that used a water and air heat exchanger. In the latter PV/T system, air passed through both the top of the PV panel and the bottom of it while water passed through only the bottom of the panel in a separate heat exchanger. In this way, the water and air absorbed the thermal energy of the panel by means of separate heat exchangers, simultaneously. In addition to the two systems mentioned above, an uncooled photovoltaic module was also designed in order to compare the systems. As a result, three different modules were designed. This study was conducted in a natural ambient environment and on days which had different climatic conditions. The thermal, electrical and overall efficiencies of each PV/T module were determined. The results were compared with the uncooled module electrical efficiency. The results showed that when water and air were used together, it was more efficient than single usage in a PV/T system. The thermal gain of the working fluids was also found to be fairly high and so, the gained energy could be used for different purposes. For example, hot air could be used in drying systems and air condition systems. Hot water could be used in hot water supply systems.

Experimental Characterization of a Natural Convection Heat Exchanger for Solar Domestic Hot Water Systems

Solar Energy ◽  
2006 ◽  
Author(s):  
Cynthia A. Cruickshank ◽  
Stephen J. Harrison
Keyword(s):  
Natural Convection ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Computational Models ◽  
Operating Conditions ◽  
Hot Water ◽  
Test Method ◽  
Convection Flow ◽  
Convection Heat ◽  
Domestic Hot Water

To predict the long-term performance of solar domestic hot water (SDHW) systems requires computational models that can characterize the systems under a range of operating conditions. The development of detailed fundamental models that suitably describe the operation of systems with natural convection heat exchangers is, however, difficult and time consuming. The fact that the natural convection flow through the heat exchanger is intrinsically self-controlling and temperature dependent complicates the analysis. One approach to modeling this type of system is to use performance characteristics, empirically derived from experimental data, to predict the performance of the heat exchanger under typical operating conditions. Unfortunately, a significant number of tests may be required to characterize the full operation of the device. This paper presents a simplified test method that was developed to allow pre-configured SDHW systems that use natural convection heat exchangers, to be characterized. The results of this test method produce performance coefficients for simple empirical expressions that describe the fluid flow and heat transfer in the heat-exchange loop. These empirically derived coefficients are an input to a general simulation routine that allows overall system performance to be determined for various loads and climatic conditions. In this paper, data is presented for a typical heat exchanger under a range of operational conditions.

scholarly journals Heat Exchanger Design and System Balance of an Air Source Heat Pump/Chiller Using Brazed Plate Heat Exchangers

1997 ◽  
Author(s):  
Changiz Tolouee
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Operating Conditions ◽  
Hot Water ◽  
Pump Efficiency ◽  
Plate Heat ◽  
Air Source Heat Pump ◽  
Water Side ◽  
Brazed Plate Heat Exchangers

Air Source heat pump/chiller is used to provide chilled water for cooling and hot water for heating purposes. This is one investment for both applications with no requirement for boiler and fuel with the advantage of heat pump efficiency. In this paper we are going to analyse both air side and water side heat exchangers used in air source heat pump/chiller with special attention and emphasis on brazed plate heat exchanger which is used in refrigerant to water side of this unit in order to achieve optimum performance in both the heat pump and chiller operations. Due to compactness of brazed plate heat exchangers it is very important to balance system volume in both operating conditions which will also be examined in this paper.

scholarly journals On the efficiency of the control of the circulation of hot water

2021 ◽  
Vol 22 (6) ◽  
pp. 117-129
Author(s):  
P. V. Rotov ◽  
A. A. Sivukhin ◽  
M. A. Rotova ◽  
R. A. Gafurov ◽  
A. V. Gorshkov
Keyword(s):  
Water Supply ◽  
Flow Control ◽  
Residential Buildings ◽  
Operating Conditions ◽  
Hot Water ◽  
Heat Consumption ◽  
Load Control ◽  
Water Supply Systems ◽  
Hot Water Supply ◽  
Supply Systems

PURPOSE. Perform analysis of the actual heat energy consumption for cold water heating for the hot water utility to the approved standard. Compare different methods of flow control in circulation pipelines of hot water supply systems. Identify ways to improve the efficiency of hot water systems. METHODS. The passive engineering experiment was used to study the operating modes of hot water supply systems of several groups of houses, in which various methods of regulating water consumption in hot water supply systems are implemented. Data collection was carried out using the online system of control and commercial accounting of energy resources. RESULTS. Existing hot water supply systems in residential buildings of Ulyanovsk were inspected under various methods of flow control in circulation pipelines. Features of static and dynamic load control of hot water supply systems were investigated. Analysis of influence of methods of control of thermal load of hot water supply systems on their actual heat consumption was performed. The possibility of bringing the actual operation mode of hot water supply systems to the standard value, on the basis of which consumption is calculated, is estimated. CONCLUSION. Known methods of load control in hot water supply systems and their actual operating conditions do not allow to reach the level of heat consumption that meets the established standards. Conclusions were drawn on the need to revise the regulated indicators of hot water quality and to adjust the method of calculating consumption in hot water supply systems.

scholarly journals Diagnostics of a Domestic Hot Water Storage Tank under Operating Conditions

Processes ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1771
Author(s):  
Paweł Obstawski ◽  
Monika Janaszek-Mańkowska ◽  
Arkadiusz Ratajski
Keyword(s):  
Heat Exchanger ◽  
Dynamic Properties ◽  
Water Storage ◽  
Operating Conditions ◽  
Hot Water ◽  
Domestic Hot Water ◽  
Water Storage Tank ◽  
Coil Heat Exchanger ◽  
Coil Heat

This paper presents a new method for the diagnostics of a hot water storage tank under operating conditions. Depending on the operating point of the tank, the method enables determination of thermal conductivity coefficients of the coil heat exchanger, which allows us to determine the intensity of heat transfer between the transfer medium and water in the tank as well as of tank walls, which consequently enables determination of heat losses to the environment. Furthermore, the dynamic properties of the tank may also be determined by applying this method. The advantage of this method is possibility of analyzing changes in the material constants of the coil heat exchanger, tank walls, and dynamic properties of the tank as a function of mass flow of the medium supplying the coil heat exchanger. The possibility of determining coefficients of thermal conductivity as well as the inertia of tank and exchanger, based on temperature measurements acquired in operating conditions is a novelty in this paper. Knowing the variability of material constants and of dynamic properties of the tank as a function of medium flow rate allows multicriteria optimization to be performed which, with a conventional design of the tank, results in a reduction of up to 10% in the time taken to prepare domestic hot water.

Experimental Investigation of Heat Transfer Enhancement by Using Different Number of Fins in Circular Tube

2018 ◽  
Vol 6 (3) ◽  
pp. 1-12
Author(s):  
Kamil Abdul Hussien
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Cold Water ◽  
Finned Tube ◽  
Hot Water ◽  
Copper Tube ◽  
Smooth Tube ◽  
Tube Heat Exchanger ◽  
Mass Flow Rates ◽  
Flow Heat

Abstract-The present work investigates the enhancement of heat transfer by using different number of circular fins (8, 10, 12, 16, and 20) in double tube counter flow heat exchanger experimentally. The fins are made of copper with dimensions 66 mm OD, 22 mm ID and 1 mm thickness. Each fin has three of 14 mm diameter perforations located at 120o from each to another. The fins are fixed on a straight smooth copper tube of 1 m length, 19.9 mm ID and 22.2 mm OD. The tube is inserted inside the insulated PVC tube of 100 mm ID. The cold water is pumped around the finned copper tube, inside the PVC, at mass flow rates range (0.01019 - 0.0219) kg/s. The Reynold's number of hot water ranges (640 - 1921). The experiment results are obtained using six double tube heat exchanger (1 smooth tube and the other 5 are finned one). The results, illustrated that the heat transfer coefficient proportionally with the number of fin. The results also showed that the enhancement ratio of heat transfer for finned tube is higher than for smooth tube with (9.2, 10.2, 11.1, 12.1 13.1) times for number of fins (8, 10, 12, 16 and 20) respectively.

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