A general steady state mathematical model for fin-and-tube heat exchanger based on graph theory

2004 ◽  
Vol 27 (8) ◽  
pp. 965-973 ◽  
Author(s):  
Jian Liu ◽  
WenJian Wei ◽  
GouLiang Ding ◽  
Chunlu Zhang ◽  
Masaharu Fukaya ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Graph Theory ◽  
Steady State ◽  
Heat Exchanger ◽  
Tube Heat Exchanger

Interaction Between Secondaries in a Thermal-Hydraulic Network

2006 ◽  
Vol 128 (4) ◽  
pp. 820-828 ◽  
Author(s):  
Weihua Cai ◽  
Walfre Franco ◽  
Gregor Arimany ◽  
Mihir Sen ◽  
K. T. Yang ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Heat Exchanger ◽  
Flow Rate ◽  
Significant Interaction ◽  
Step Change ◽  
The Other ◽  
Thermal Interaction ◽  
Order Of Magnitude ◽  
Hydraulic Network

The design of one secondary loop of a complex network often neglects the effect that its operation has on the others. The present is a study of hydrodynamic and thermal interaction between secondaries in a thermal-hydraulic network as the system goes from one steady state to another. Experimental results are related to those derived from a mathematical model. The network consists of a primary and three secondary loops. There is a water-to-water heat exchanger on each secondary, with the cooling coming from the primary and the heating from a separate loop. A step change is introduced by manually actuating a valve in one of the secondaries, resulting in changes in the other loops also. The response time of the temperature is found to be an order of magnitude higher than that of the flow rate, which is again an order of magnitude higher than the pressure difference. The steady-state results show that there is significant interaction, and that it is dependent on the initial operating condition. The hydrodynamic and thermal responses are found to be very different.

Techno-Economic Analysis of an Earth-Air Heat Exchanger for Cooling and Heating of a Building

2005 ◽  
Author(s):  
Ashish Shukla ◽  
G. N. Tiwari ◽  
M. S. Sodha
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Heat Exchanger ◽  
Air Temperature ◽  
New Delhi ◽  
Quasi Steady State ◽  
Significant Saving ◽  
Air Conditioners ◽  
Heating And Cooling ◽  
Heating Loads

In this communication a quasi-steady state mathematical model is developed to predict the air temperature at the outlet of an earth-air heat exchanger and seasonal heating and cooling potential, associated with the use of the exchanger. Seasonal values of heating and cooling potential are estimated theoretically and validated by experiments in two distinct seasons, i.e. winter and summer, corresponding to composite climate of New Delhi (28° 35′ N, 77° 12′ E) India. It is observed that there is significant saving of energy and money by reducing cooling and heating loads on air-conditioners, if earth air heat exchanger is used. There is fair agreement between theoretical values and experimentally observed values of the seasonal values of heating and cooling potentials for each season (i.e. winter and summer).

scholarly journals Experimentation and Performance Analysis of Natural Draft Wire on Tube Condenser

2019 ◽  
Vol 8 (3) ◽  
pp. 4303-4308
Keyword(s):  
Mathematical Model ◽  
Heat Exchanger ◽  
Energy Saving ◽  
Optimum Design ◽  
Cost Reduction ◽  
Atmospheric Temperature ◽  
Tube Length ◽  
Two Phase ◽  
Tube Heat Exchanger ◽  
Tube Condenser

This project is sponsored by the company Whirlpool of India Limited, situated at Ranjangaon MIDC, Pune. A simple design methodology of Wire on Tube heat exchanger used in domestic refrigeration systems focuses on both energy saving and cost reduction in this study. A wire on tube condenser is two-phase natural convection heat exchanger which rejects heat absorbed by the refrigerant in the evaporator and heat addition by compressor to atmospheric temperature changing its phase. The main objective of this research paper is to study impact of condenser tube length and number of wires, its pitches on performance of domestic refrigerator and desire to find optimum design of wire on tube heat exchanger compatible with on/off compressor in 185 liter 3 star single door model. Mathematical model are used to analyze performance of entire refrigeration system. Experiments were conducted under controlled climatic chamber and varying ambient temperature as per BEE standard and procedures. It was found that experimental results have 5% to 8% deviation range with results obtained from mathematical model. Optimum design of wire on tube heat exchanger selected has main focus on both energy saving and cost reduction

Investigations on RELAP5-3D to RELAP5-3D Coupling Methodology by PVMEXEC

2016 ◽  
Author(s):  
Valeria Parrinello ◽  
Marco Lanfredini ◽  
Alessandro Petruzzi ◽  
Marco Cherubini
Keyword(s):  
Steady State ◽  
Heat Exchanger ◽  
Nuclear Power ◽  
Power Plants ◽  
Coupled Model ◽  
Nuclear System ◽  
Tube Heat Exchanger ◽  
Parallel Virtual Machine ◽  
Solution Algorithms ◽  
Accident Scenarios

In the framework of a BEPU (Best Estimate Plus Uncertainty) approach within the licensing process of a nuclear power plant, the need to extend the resources of nuclear system thermal-hydraulics codes, such as RELAP5-3D, arises to allow more detailed simulations of the complex 3D reality of Nuclear Power Plants (NPPs), either under normal steady-state or during various accident scenarios. Currently, it is not possible to achieve the same degree of detail for a whole nuclear system when it is simulated with RELAP5-3D and this is due to the inherent limitations in the number of components and volumes to be used for the analysis. For this reason, it is of extreme interest the use of tools for codes coupling that enable the use of different codes for the simulation of different portions of a system in a unified analysis. In this paper the attention will be focused on the decomposition of the thermal-hydraulic domain of a system into subsystems to be simulated by different instances of the same code (e.g. RELAP5-3D) coupled together by means of PVMEXEC program and parallel virtual machine (PVM) technology. Explicit and semi-implicit solution algorithms were used for the analyses. Among the analyzed cases, the following will be discussed in detail with the aim to provide additional guidelines for the use of the PVMEXEC tool: (i) the Edward’s pipe blowdown test, (ii) a simplified countercurrent heat exchanger, (iii) different hydraulics and heat structure coupling schemes for a shell-tube heat exchanger and (iv) a three-task coupled model of a simplified BWR model.

scholarly journals Experimental Verification of an Analytical Mathematical Model of a Round or Oval Tube Two-Row Car Radiator

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3399
Author(s):  
Dawid Taler ◽  
Jan Taler ◽  
Marcin Trojan
Keyword(s):  
Mathematical Model ◽  
Heat Exchanger ◽  
Heat Flow ◽  
Heat Exchangers ◽  
Cfd Simulation ◽  
Experimental Studies ◽  
Hot Water ◽  
Heat Flow Rate ◽  
Cfd Modelling ◽  
Tube Heat Exchanger

The paper presents an analytical mathematical model of a car radiator, which takes into account various heat transfer coefficients (HTCs) on each row of pipes. The air-side HTCs in a specific row of pipes in the first and second passes were calculated using equations for the Nusselt number, which were determined by CFD simulation by the ANSYS program (Version 19.1, Ansys Inc., Canonsburg, PA, USA). The liquid flow in the pipes can be laminar, transition, or turbulent. When changing the flow form from laminar to transition and from transition to turbulent, the HTC continuity is maintained. Mathematical models of two radiators were developed, one of which was made of round tubes and the other of oval tubes. The model allows for the calculation of the thermal output of every row of pipes in both passes of the heat exchangers. Small relative differences between the total heat flow transferred in the heat exchanger from hot water to cool air exist for different and uniform HTCs. However, the heat flow rate in the first row is much higher than the heat flow in the second row if the air-side HTCs are different for each row compared to a situation where the HTC is constant throughout the heat exchanger. The thermal capacities of both radiators calculated using the developed mathematical model were compared with the results of experimental studies. The plate-fin and tube heat exchanger (PFTHE) modeling procedure developed in the article does not require the use of empirical correlations to calculate HTCs on both sides of the pipes. The suggested method of calculating plate-fin and tube heat exchangers, taking into account the different air-side HTCs estimated using CFD modelling, may significantly reduce the cost of experimental research for a new design of heat exchangers implemented in manufacturing.

MATHEMATICAL MODEL AND CFD SIMULATION OF A DOUBLE TUBE HEAT EXCHANGER

2018 ◽  
Author(s):  
Daniel Florez ◽  
Elena Peñaranda ◽  
Abdul Orlando Cárdenas Gómez ◽  
ENIO BANDARRA FILHO
Keyword(s):  
Mathematical Model ◽  
Heat Exchanger ◽  
Cfd Simulation ◽  
Tube Heat Exchanger
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