Linear Matrix Operator Formalism for Basic Heat Exchanger Thermal Design

1988 ◽  
Vol 110 (2) ◽  
pp. 297-303 ◽  
Author(s):  
A. Pignotti
Keyword(s):  
Heat Exchanger ◽  
Variable Temperature ◽  
Practical Interest ◽  
Thermal Design ◽  
Matrix Operator ◽  
Linear Matrix ◽  
Inlet Temperature ◽  
Matrix Formalism ◽  
Temperature Distributions ◽  
The Matrix

The matrix formalism used for the thermal description of heat exchangers is extended to include streams with variable temperature distributions. In this approach, a heat exchanger is described by a temperature-independent matrix operator, which, acting on the inlet temperature distributions, generates the outlet ones. This formalism is particularly useful for the evaluation of the thermal effectiveness of complex heat exchanger configurations that can be broken into simple constitutive parts, linked to each other by unmixed streams. Applications to crossflow configurations of practical interest are shown.

Some Alternative Technologies for Solar Thermal Power Generation

Solar Energy ◽  
2006 ◽  
Author(s):  
Motoaki Utamura ◽  
Yutaka Tamaura ◽  
Hiroshi Hasuike
Keyword(s):  
Heat Exchanger ◽  
Thermal Power ◽  
Thermal Design ◽  
Optical Systems ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Regenerative Heat ◽  
Turbine Inlet ◽  
The Cross ◽  
Field Efficiency

Two advanced optical systems and a highly efficient thermal cycle suitable for beam-down power tower with thermal storage are presented. (1) To increase field efficiency, the “cross beam” heliostat array concept is proposed. Using continuum optical model, the characteristics of the cross beam concept and its economy were investigated. (2) To protect the central reflector (CR) against wind force, a “multi-ring CR” concept is proposed. The concentration performance of multi-ring CRs is calculated using the ray-tracing method. It shows no worse results than the case with a single hyperboloid mirror. (3) The potential of a closed gas turbine cycle with supercritical carbon dioxide as a working fluid was investigated. An optimal cycle configuration involves a regenerative cycle with pre-cooling and inter-cooling cycles, in which theoretically achievable cycle thermal efficiency is 47% at the turbine inlet temperature of 800 K and turbine inlet pressure of 20 MPa. Detailed thermal design of a critical component, regenerative heat exchanger (RHX) is carried out using a newly developed printed heat exchanger (PCHE). It proved to be a feasible design.

Matrix Formalism for Complex Heat Exchangers

1984 ◽  
Vol 106 (2) ◽  
pp. 352-360 ◽  
Author(s):  
A. Pignotti
Keyword(s):  
Finite Number ◽  
Model Calculation ◽  
Heat Exchangers ◽  
Practical Interest ◽  
Explicit Solutions ◽  
Matrix Formalism ◽  
Normal Flow ◽  
The Matrix ◽  
Shell And Tube

The matrix formalism introduced by Domingos for the calculation of the effectiveness of assemblies of heat exchangers is extended to the case of complex exchangers, for which the restriction of complete mixing for each fluid in the inlet and outlet streams is relaxed. Rectangular matrices are used to relate the inlet and outlet temperatures, and their properties are discussed. The method can be used to find explicit solutions for configurations of practical interest, which are analyzed as assemblies of simpler units, coupled together in various ways. The formalism is illustrated by a model calculation of a 1–2 shell-and-tube exchanger with a finite number of baffles, for TEMA E (normal flow) and TEMA J (divided flow) types of shells.

Temperature Transients in a Triple Heat Exchanger

1984 ◽  
Vol 198 (3) ◽  
pp. 145-154
Author(s):  
P C Chiu ◽  
E H K Fung
Keyword(s):  
Heat Exchanger ◽  
Nuclear Reactor ◽  
Reactor Power ◽  
Solar Heating ◽  
Inlet Temperature ◽  
Exchange Processes ◽  
Flow Experiments ◽  
Heating Plant ◽  
Reactor Power Plant ◽  
Secondary Fluid

A triple heat exchanger, so called because there are three heat exchange processes taking place in it, was built to simulate the system behaviour of a nuclear reactor power plant or a solar heating plant which is characterized by the two circulating loops of the fluid flow. Experiments were carried out to study the temperature transients under disturbances in secondary fluid inlet temperature and power output from immersion heaters. Numerical results were obtained from the weighted residual formulation of the proposed dynamic model and they were shown to be in general agreement with the two sets of experimental responses.

scholarly journals LMI-Based Stability Criterion of Impulsive T-S Fuzzy Dynamic Equations via Fixed Point Theory

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Ruofeng Rao ◽  
Zhilin Pu
Keyword(s):  
Fixed Point ◽  
Stability Criterion ◽  
High Efficiency ◽  
Fixed Point Theory ◽  
Point Theory ◽  
Linear Matrix ◽  
The Matrix ◽  
Matrix Exponential Function ◽  
Takagi Sugeno ◽  
First Time

By formulating a contraction mapping and the matrix exponential function, the authors apply linear matrix inequality (LMI) technique to investigate and obtain the LMI-based stability criterion of a class of time-delay Takagi-Sugeno (T-S) fuzzy differential equations. To the best of our knowledge, it is the first time to obtain the LMI-based stability criterion derived by a fixed point theory. It is worth mentioning that LMI methods have high efficiency and other advantages in largescale engineering calculations. And the feasibility of LMI-based stability criterion can efficiently be computed and confirmed by computer Matlab LMI toolbox. At the end of this paper, a numerical example is presented to illustrate the effectiveness of the proposed methods.

Dynamic Analysis of Elastic Link Mechanisms by Reduction of Coordinates

1972 ◽  
Vol 94 (2) ◽  
pp. 577-581 ◽  
Author(s):  
R. C. Winfrey
Keyword(s):  
Dynamic Analysis ◽  
Complete Solution ◽  
Practical Interest ◽  
Elastic Behavior ◽  
Computational Time ◽  
Linear Matrix ◽  
Considerable Saving ◽  
Matrix Differential Equations ◽  
Elastic Link ◽  
Matrix Differential

Techniques for the solution of linear matrix differential equations have previously been applied to the dynamic analysis of a mechanism. However, because the mechanism changes geometry as it rotates, a large number of solutions are necessary to predict the mechanism’s elastic behavior for even a few revolutions. Also, a designer is frequently concerned with the elastic behavior of only one point on the mechanism and has no practical interest in a complete solution. For these reasons, a method is given here for reducing the total number of coordinates to one coordinate at the point of design interest. A considerable saving in computational time is obtained since the dynamic solution involves one degree of freedom instead of many. Further, since any solution will make use of some limiting assumptions, results here indicate that, for design purposes, reducing the coordinates does not significantly affect comparable accuracy.

Design and Control of Bypass Condensers

2012 ◽  
Author(s):  
Ranga Nadig ◽  
Michael Phipps
Keyword(s):  
Thermal Design ◽  
Waste To Energy ◽  
Inlet Temperature ◽  
Circulating Water ◽  
Large Shell ◽  
Small Tube ◽  
And Performance ◽  
And Control ◽  
Proper Performance ◽  
Energy Plants

In waste to energy plants and certain genre of cogeneration plants, it is mandatory to condense the steam from the boiler or HRSG in a separate bypass condenser when the steam turbine is out of service. The steam from the boiler or HRSG is attemperated in a pressure reducing desuperheating valve and then condensed in a bypass condenser. To avoid flashing of condensate in downstream piping it is customary to subcool the condensate in the bypass condenser. Circulating water from the steam surface condenser is used to condense the steam in the bypass condenser. Some of the challenges involved in the design of the bypass condenser are: • High shellside design pressure and temperature • Condensate subcooling • Large circulating water (tubeside) flow rate • Relatively low circulating water (tubeside) inlet temperature • Large Log Mean Temperature Difference (LMTD) • Large shell diameters • Small tube lengths The diverse requirements complicate the mechanical and thermal design of the bypass condenser. This paper highlights the complexities in the design and performance of the bypass condenser. Similarities with the design and operation of steam surface condensers and feedwater heater are reviewed. The uniqueness of the bypass condenser’s design and operation are discussed and appropriate solutions to ensure proper performance are suggested.

scholarly journals Analytical and Experimental Investigation of a Plate Fin Heat Exchanger at Cryogenics Temperature

2021 ◽  
Vol 39 (4) ◽  
pp. 1225-1235
Author(s):  
Ajay K. Gupta ◽  
Manoj Kumar ◽  
Ranjit K. Sahoo ◽  
Sunil K. Sarangi
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Cryogenic Temperature ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Compact Size

Plate-fin heat exchangers provide a broad range of applications in many cryogenic industries for liquefaction and separation of gasses because of their excellent technical advantages such as high effectiveness, compact size, etc. Correlations are available for the design of a plate-fin heat exchanger, but experimental investigations are few at cryogenic temperature. In the present study, a cryogenic heat exchanger test setup has been designed and fabricated to investigate the performance of plate-fin heat exchanger at cryogenic temperature. Major parameters (Colburn factor, Friction factor, etc.) that affect the performance of plate-fin heat exchangers are provided concisely. The effect of mass flow rate and inlet temperature on the effectiveness and pressure drop of the heat exchanger are investigated. It is observed that with an increase in mass flow rate effectiveness and pressure drop increases. The present setup emphasis the systematic procedure to perform the experiment based on cryogenic operating conditions and represent its uncertainties level.

scholarly journals Thermal Analysis of the Effects of Multifaceted Conditions on Performance of Shell-and-Tube Heat Exchanger

2021 ◽  
Vol 6 (1) ◽  
pp. 69-75
Author(s):  
Taiwo O. Oni ◽  
Ayotunde A. Ojo ◽  
Daniel C. Uguru-Okorie ◽  
David O. Akindele
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Parallel Flow ◽  
Hot Water ◽  
Inlet Temperature ◽  
Fiber Glass ◽  
Counter Flow ◽  
Tube Heat Exchanger ◽  
Shell And Tube ◽  
Flow Configurations

A shell-and-tube heat exchanger which was subjected to different flow configurations, viz. counter flow, and parallel flow, was investigated. Each of the flow configurations was operated under two different conditions of the shell, that is, an uninsulated shell and a shell insulated with fiber glass. The hot water inlet temperature of the tube was reduced gradually from 60 oC to 40 oC, and performance evaluation of the heat exchanger was carried out. It was found that for the uninsulated shell, the heat transfer effectiveness for hot water inlet temperature of 60, 55, 50, 45, and 40 oC are 0.243, 0.244, 0.240, 0.240, and 0.247, respectively, for the parallel flow arrangement. For the counter flow arrangement, the heat transfer effectiveness for the uninsulated shell are 2.40, 2.74, 5.00, 4.17, and 2.70%, respectively, higher than those for the parallel flow. The heat exchanger’s heat transfer effectiveness with fiber-glass-insulated shell for the parallel flow condition with tube hot water inlet temperatures of 60, 55, 50, 45, and 40 oC are 0.223, 0.226, 0.220, 0.225, and 0.227, respectively, whereas the counter flow condition has its heat transfer effectiveness increased by 1.28, 1.47, 1.82, 1.11, and 1.18%, respectively, over those of the parallel flow.

IMPORTANCE OF 3D VEHICLE HEAT EXCHANGER MODELING

2021 ◽  
pp. 1-10
Author(s):  
Michal Schmid ◽  
Fatih Bozkurt ◽  
Petr Pašcenko ◽  
Pavel Petržela
Keyword(s):  
Fluid Flow ◽  
Heat Exchanger ◽  
Fluid Velocity ◽  
Coolant Temperature ◽  
Inlet Temperature ◽  
Vehicle Simulation ◽  
Velocity Magnitude ◽  
Primary Fluid ◽  
The Difference ◽  
Inlet Conditions

Abstract The work demonstrates, via a comprehensive study, the necessity of using a 3D CFD approach for heat exchanger (HTX) modelling within underhood vehicle simulation. The results are presented as the difference between 1D and 3D CFD approaches with a focus on auxiliary fluid (e.g. coolant) temperature prediction as a function of primary fluid (e.g. air) inlet conditions. It has been shown that the 1D approach could significantly underpredict auxiliary fluid inlet temperature due to neglecting the spatial distribution of primary fluid velocity magnitude. The resultant difference in the auxiliary fluid flow HTX inlet temperature is presented and discussed as a function of the Uniformity Index (UI) of the primary fluid flow velocity magnitude. Additionally, the 3D HTX model's importance is demonstrated in an industrial example of full 3D underhood simulation.

Sign in / Sign up

Export Citation Format

Share Document