Dusan Gvozdenac - Academia.edu (original) (raw)

Papers by Dusan Gvozdenac

Research paper thumbnail of Two-pass countercrossflow heat exchangers with both fluids unmixed throughout

Wärme- und Stoffübertragung (Zeitschrift. 1968), Jun 1, 1986

Research paper thumbnail of Dynamic response of the crossflow heat exchanger with finite wall capacitance

Wärme- und Stoffübertragung (Zeitschrift. 1968), Jul 1, 1991

This paper shows how the transient response of a cross-flow heat exchanger with finite wall capac... more This paper shows how the transient response of a cross-flow heat exchanger with finite wall capacitance may be calculated by analytical method. Making usual idealizations for the analysis of dynamic behavior of the heat exchanger, the model is based on three local energy balance equations which are solved by using the Laplace transform method for step change of the primary fluid inlet temperature. The solutions are found in the case of constant initial conditions and expressed in the explicit analytical form used to find temperature distributions of both fluids and the wall as well as the mean mixed fluid temperatures at the exit. Presented solutions are valid in cases where fluid velocities are different or equal and finite or infinite, respectively.The solutions can be very suitable for mathematical modeling systems containing such types of heat exchangers.ZusammenfassungDiese Arbeit zeigt wie das Eigenschwingverhalten von einem Querstrom-Wärmeaustauscher mit endlicher Wärmekapazität durch ein analytisches Verfahren berechnet werden kann. Es wurden gewöhnliche Idealisierungen für die Berechnung des dynamischen Verhaltens des Wärmeaustauschers gemacht. Das Modell basiert auf der Grundlage der drei lokalen Energiebilanzgleichungen, welche mit der Laplace-Transformation gelöst werden, für die schrittweise Änderung der primären Fluideintrittstemperatur. Lösungen wurden für den Fall gefunden, daß die Anfangsbedingungen konstant sind und werden in der expliziten Schreibweise ausgedrückt, um die Temperaturverteilungen der beiden Fluide und der Wand genauso gut zu erhalten wie die Fluidgemischtemperaturen am Ausgang. Die dargestellten Lösungen sind für den Fall gültig, daß die Fluidgeschwindigkeiten verschieden oder gleich bzw. endlich oder unendlich sind. Diese Lösungen können für mathematische Modellsysteme, die diese Typen des Wärmeaustauschers beinhalten, sehr geeignet sein.

Research paper thumbnail of Compressed Air System

John Wiley & Sons, Ltd eBooks, Mar 18, 2009

Research paper thumbnail of Analytical Solution of the Transient Response of Gas-to-Gas Crossflow Heat Exchanger With Both Fluids Unmixed

Journal of heat transfer, Nov 1, 1986

The dynamic response of a single-pass crossflow heat exchanger with both fluids unmixed to arbitr... more The dynamic response of a single-pass crossflow heat exchanger with both fluids unmixed to arbitrary time varying inlet temperatures of fluids is investigated analytically. The initial spatial temperature distribution of the heat exchanger core is arbitrary as well. Analytical solutions for temperature distributions of both fluids and the wall as well as the mean mixed fluid temperatures at the exit are presented. The solutions are found by using Laplace transform method and special functions in the form of series of modified Bessel functions.

Research paper thumbnail of Sustavno gospodarenje energijom i upravljanje utjecajima na okoliš u industriji

Research paper thumbnail of Analytical Solution of Transient Response of Gas-to-Gas Parallel and Counterflow Heat Exchangers

Journal of heat transfer, Nov 1, 1987

This paper shows how the transient response of gas-to-gas parallel and counterflow heat exchanger... more This paper shows how the transient response of gas-to-gas parallel and counterflow heat exchangers may be calculated by an analytical method. Making the usual idealizations for analysis of dynamic responses of heat exchangers, the problem of finding the temperature distributions of both fluids and the separating wall as well as the outlet temperatures of fluids is reduced to the solution of an integral equation. This equation contains an unknown function depending on two independent variables, space and time. The solution is found by using the method of successive approximations, the Laplace transform method, and special functions defined in this paper.

Research paper thumbnail of Experimental prediction of heat transfer coefficients by use of a double-blow method

Wärme- und Stoffübertragung (Zeitschrift. 1968), Jun 1, 1994

A new method is proposed for evaluating heat transfer coefficients in a heat exchanger matrix. In... more A new method is proposed for evaluating heat transfer coefficients in a heat exchanger matrix. In comparison with the well known single-blow method, a new double-blow method offers prediction of heat transfer coefficients on both sides of the heat exchanger wall by using one run only, because temperatures of both fluids flowing through the heat exchanger matrix are changed and measured.The experimental technique, data collection procedure, and the method of analysis are derived from an analysis of the analytical solution of the transient response of gas-to-gas cross flow heat exchanger with finite wall capacitance.ZusammenfassungZur Ermittlung von Wärmeübergangskoeffizienten in einer Wärmetauschermatrix wird ein neues Verfahren vorgeschlagen. Im Vergleich mit der wohlbekannten Einzelbeaufschlagungsmethode ermöglicht ein neues Doppelbeaufschlagungsverfahren die Ermittlung von Wärmeübergangskoeffizienten auf beiden Seiten der Wärmetauschertrennwand in nur einem Versuchslauf, da die Temperaturen beider, den Wärmetauscher durchströmenden Medien gemessen werden.Die experimentelle Technik, das Datenkollokationsverfahren und das Berechnungsverfahren wurden ausgehend von der analytischen Lösung für das Übertragungsverhalten eines Gas/Gas-Kreuzstrom-Wärmetauschers mit endlicher Wärmekapazität der Wand entwickelt bzw. abgeleitet.

Research paper thumbnail of Industrial Steam System

John Wiley & Sons, Ltd eBooks, Mar 18, 2009

This chapter contains sections titled: System Description System Performance Definition Principle... more This chapter contains sections titled: System Description System Performance Definition Principles of Performance Analysis Analysis of Boiler Performance Factors Influencing Boiler Performance Opportunities for Boiler Performance Improvement Software for Boiler Performance Analysis Boiler Performance Monitoring Steam Distribution and Condensate Return System Condensate Return System Environmental Impacts Bibliography ]]>

Research paper thumbnail of Nonlinear transient temperature field in a hexagon

Ingenieur-Archiv, 1980

SummaryAn approximate direct method for solving nonlinear transient heat conduction problem in th... more SummaryAn approximate direct method for solving nonlinear transient heat conduction problem in the hexagon, based on Gauss' principle of least constraint is presented. The problem is reduced to the algebraic minimization of a quadratic form with respect to the physical components of the temporal and spatial changes of temperature field. For various values of specific heat and thermal conductivity temperature coefficients the comparison of approximate solutions with the numerical ones is performed and an agreement is found.ÜbersichtEs wird eine auf dem Gaußschen Prinzip des kleinsten Zwanges gegründete direkte Näherungsmethode für die Lösung nichtlinearer instationärer Wärmeleitungsprobleme dargestellt. Das Problem wird auf die algebraische Minimisation einer quadratischen Form bezüglich der physikalischen Parameter der Zeit- und Raumvariablen des Temperaturfeldes zurückgeführt. Die Lösung wird für verschiedene Werte der Temperaturkoeffizienten, der spezifischen Wärmekapazität und der Wärmeleitfähigkeit mit der numerischen Lösung verglichen, wobei eine gute Übereinstimmung erreicht wird.

Research paper thumbnail of Analytical solution for transient response of counter flow heat exchanger with finite wall capacitance

Wärme- und Stoffübertragung (Zeitschrift. 1968), Jun 1, 1993

Research paper thumbnail of Analytical Solution of Dynamic Response of Heat Exchanger

InTech eBooks, Mar 9, 2012

Heat Exchangers-Basics Design Applications 54 in which both fluids are gases. The paper (Gvozdena... more Heat Exchangers-Basics Design Applications 54 in which both fluids are gases. The paper (Gvozdenac, 1987) shows analytical solution for transient response of parallel and counter flow heat exchangers. However, these solutions are limited to the case in which heat capacities of both fluids are negligibly small in relation to the heat exchanger's separating wall capacity. Moreover, it is important to mention that papers (Romie, 1983), (Gvozdenac, 1986), (Spiga & Spiga, 1987) and (Spiga & Spiga, 1988) deal with two-dimensional problems of transition for cross flow heat exchangers with both fluids unmixed throughout. The last paper is the most general one and provides opportunities for calculating transient temperatures of wall temperatures and of both fluids by an analytical method for finite flow velocities and finite wall capacity. The paper (Gvozdenac, 1990) shows analytical solution of transient response of the parallel heat exchanger with finite heat capacity of the wall. The procedure presented in the above paper is also used for resolving dynamic response of the cross flow heat exchanger with the finite wall capacity (Gvozdenac, 1991). A very important book is that of Roetzel W and Xuan Y (Roetzel & Xuan, 1999) which provides detailed analysis of all important aspects of the heat exchanger's dynamic behavior in general. It also gives detailed overview and analysis of literature. This paper shows solutions for energy functions which describe convective heat transfer between the wall of a heat exchanger and fluid streams of constant velocities. The analysis refers to parallel, counter and cross flow heat exchangers. Initial fluids and wall temperatures are equal but at the starting moment, there is unit step change of inlet temperature of one of the fluids. The presented model is valid for finite fluid velocities and finite heat capacity of the wall. The mathematical model is comprised of three linear partial differential equations which are resolved by manifold Laplace transforms. To a certain extent, this paper presents a synthesis of the author's pervious papers with some simplified and improved final solutions. The availability of such analytical solutions enables engineers and designers a much better insight into the nature of heat transfers in parallel, counter and cross flow heat exchangers. For the purpose of easier practical application of these solutions, the potential users are offered MS Excel program at the web address: www.peec.uns.ac.rs. This program is open and can be not only adjusted to special requirements but also modified. 2. Mathematical formulation Regardless of seeming similarity of partial differential equations arising from mathematical modeling, this paper analyzes parallel, cross and counter flow heat exchangers separately. However, simplifying assumptions in the derivation of differential equations are the same and are as follows: a. Heat transfer characteristics and physical properties are independent of temperature, position and time; b. The fluid velocity is constant in each flow passage; c. Axial conduction is negligible in both fluids and the wall; d. Overall heat losses are negligible; e. The heat generation and viscous dissipation within the fluids are negligible; f. Fluids are assumed to be finite-velocity liquids or gases. This means that the fluid transit or dwell times are not small compared to the duration of transience.

Research paper thumbnail of Transient response of the parallel flow heat exchanger with finite wall capacitance

Ingenieur-Archiv, 1990

This paper shows how the transient response of the parallel heat exchanger with finite wall capac... more This paper shows how the transient response of the parallel heat exchanger with finite wall capacitance may be calculated by an analytical method. Making usual idealizations for the analysis of dynamic behavior of the heat exchanger, the model is based on three local energy balance equations which are solved by using ~he Laplace transform method for step change of the primary fluid inlet temperature. The solutions are found in the case of constant initial conditions and expressed in explicit analytical form in terms of the number of transfer units, heat capacity ra~ios, heat transfer resistance and flow capacitance ratios. The presented solutions are valid in cases where fluid velocities are different or equal and finite or infinite. The solutions can be very suitable for the mathematical modeling of systems containing such types of heat exchangers. Das (~bergangsverhalten des Gleichstrom-W~irmetauschers mit endlieher Wiirmekapazit~it der W~nde [~bersieht: Vorgestellt wird eine analytische Berechnungsmethode ffir das Ubergangsverhalten helm Gleichstrom-W~.rmetauscher mit endlicher Wandkapaziti~t. Mit den fiblichen Idealisierungen ffir die Behandlung des dynamischcn Verhaltens yon W~rmetauschern geht die Modellierung aus yon drei lokalcn Energiebilanz-Gleichungen, die mit I-Iilfe der Laplace-Transformation ffir einen Sprung in der Einlauftemperatur des prim~ren Fluids gel6st werden. Die L6sungen, die man ffir konstante Anfangsbedingungen erh~lt, werden in expliziter analytischer Form und in Abhi~ngigkeit yon der Zahl der ~bertragungseinheiten, der Verhiiltnisse der WgrmeinhMte, der W~rmefibergangswiderstiinde and Durchflugkapazitgten dargestellt. Die angegebenen LSsungcn gelten fiir gleiche und verschiedene sowie endliche oder unendliche Str6mungsgeschwindigkeiten.

Research paper thumbnail of Relationship between Energy Use and Production Volume

John Wiley & Sons, Ltd eBooks, Mar 18, 2009

This chapter contains sections titled: Introduction Energy/Production Relationship by Design Ener... more This chapter contains sections titled: Introduction Energy/Production Relationship by Design Energy/Production Relationship by Standard Operational Procedure Presenting the Dynamics of the Energy/Production Relationship by Scatter Diagram Interpretation of Energy/Production Data Pattern on the Scatter Diagram Statistical Methods for Energy/Production Variability Analysis Meaning and Use of the Regression Line in Energy Performance Evaluation Summary of Presenting and Analyzing the Energy/Production Relationship Bibliography

Research paper thumbnail of Performances of Three-Fluid Single Pass Crossflow Heat Exchanger

Research paper thumbnail of Systematic management of energy and environmental impacts in the industry

Knjiga „Sustavno gospodarenje energijom i upravljanje utjecajima na okolis u industriji“ pruža op... more Knjiga „Sustavno gospodarenje energijom i upravljanje utjecajima na okolis u industriji“ pruža opsežan pregled problematike energetske efikasnosti i utjecaja na okolis s naglaskom na primjenu tehnickih i menadžerskih rjesenja za povecanje energetske efikasnosti industrijskih postrojenja Ova knjiga ce sigurno biti i dobar sveucilisni udžbenik za studente, ali i odlicna strucna podloga svim ljudima koji brinu o potrosnji energije i utjecajima na okolis u industrijskim pogonima i ciji je cilj kontinuirano poboljsavanje energetske efikasnosti i smanjenje stetnih emisija u okolis.

Research paper thumbnail of The Influence of Power Loss Coefficient and Other Factors to the Primary Energy Saving of a Cogeneration Power Plant in Thailand

For CHP plants which include fully or partially condensing steam turbine, electrical/mechanical e... more For CHP plants which include fully or partially condensing steam turbine, electrical/mechanical electricity generation will decline as steam extraction increases for a given fuel energy consumption, hence there needs a balance between increasing heat energy recovery and reducing electrical/mechanical energy output assuming a constant fuel energy input. Through a daily energy supply data over a year in one of the cogeneration power plants in Thailand, the influence of power loss coefficient to Primary Energy Saving (PES) or efficiency is analyzed. Power loss coefficient used in the calculations was defined as per the basic theory of power loss coefficient in CHP Manual by EU Parliament and CHP Methodology by UNFCCC. Calculation of saving of primary energy according using cogeneration system follows the EU Manual; setting of CHP overall efficiency must be same with overall efficiency of power plant. Power loss coefficient just makes senses for calculation of power generated by CHP mod...

Research paper thumbnail of A Mathematical Model for Heat Transfer in Combustion Chambers of Steam Generators

Journal of Engineering for Power, 1981

This paper describes a mathematical model for determining the total heat transfer in combustion c... more This paper describes a mathematical model for determining the total heat transfer in combustion chambers of steam generators. The model is based on the energy balance of radiation in a spherical combustion chamber which is divided into a combustion zone and gaseous zone. The model was tested on a Hewlett-Packard Type 9815 A computer with 2008 program memories. Calculations were made for a number of steam generator combustion chambers of different furnace loads for which all important factors were established. The model allows a didactic analysis of factors influencing the process of combustion and heat transfer.

Research paper thumbnail of Applied Industrial Energy and Environmental Management

Applied Industrial Energy and Environmental Management, 2008

Boiler feed water (suction) 0.5-1.0 6. Boiler feed water (discharge) 1.5-2.5 7. Condensate 1.0-2.... more Boiler feed water (suction) 0.5-1.0 6. Boiler feed water (discharge) 1.5-2.5 7. Condensate 1.0-2.0 8. Circulation of hot water 1.0-3.0 STEAM 9. High pressure saturated steam 25-40 10. Medium and low pressure saturated steam 30-40 11. Saturated seam at peak load up to 50 12. Wet steam up to 25 13. Superheated steam 50-100 OIL 14. Suction line of pump up to 0.5 16. Suction line of pump (low pressure) 0.1-0.2 17. Discharge line of booster pump 1.0-2.0 18. Discharge line of burner pump up to 1.0 AIR AND SIMILAR GASES 19. Combustion air duct 12-20 20. Air inlet to boiler house 1.0-3.0 21. Compressed air pipes 20-30 22. Air with natural draft 2.0-4.0 23. Ventilation ducts (hospitals, theaters, etc.) 1.8-4.0 24. Ventilation ducts (office buildings, etc.) 2.0-4.5 EXHAUST GAS 25. Ducts at minimum load up to 4.0 26. Stack at minimum load up to 5.0 27. Boiler with one-step burner (on-off) 5.0-8.0 28. Boiler with two-step burner (high-low) 10-15 29. Boiler with modulating burner (3:1) 15-25 To keep the surface free of soot, the velocities should always exceed 3.0-4.0 m/s

Research paper thumbnail of Condensation intensity in vapour/gas mixture

W�rme - und Stoff�bertragung, 1993

Research paper thumbnail of Performances of three-pass crossflow heat exchangers: Inverted order flow arrangements

Wärme- und Stoffübertragung, 1994

ABSTRACT

Research paper thumbnail of Two-pass countercrossflow heat exchangers with both fluids unmixed throughout

Wärme- und Stoffübertragung (Zeitschrift. 1968), Jun 1, 1986

Research paper thumbnail of Dynamic response of the crossflow heat exchanger with finite wall capacitance

Wärme- und Stoffübertragung (Zeitschrift. 1968), Jul 1, 1991

This paper shows how the transient response of a cross-flow heat exchanger with finite wall capac... more This paper shows how the transient response of a cross-flow heat exchanger with finite wall capacitance may be calculated by analytical method. Making usual idealizations for the analysis of dynamic behavior of the heat exchanger, the model is based on three local energy balance equations which are solved by using the Laplace transform method for step change of the primary fluid inlet temperature. The solutions are found in the case of constant initial conditions and expressed in the explicit analytical form used to find temperature distributions of both fluids and the wall as well as the mean mixed fluid temperatures at the exit. Presented solutions are valid in cases where fluid velocities are different or equal and finite or infinite, respectively.The solutions can be very suitable for mathematical modeling systems containing such types of heat exchangers.ZusammenfassungDiese Arbeit zeigt wie das Eigenschwingverhalten von einem Querstrom-Wärmeaustauscher mit endlicher Wärmekapazität durch ein analytisches Verfahren berechnet werden kann. Es wurden gewöhnliche Idealisierungen für die Berechnung des dynamischen Verhaltens des Wärmeaustauschers gemacht. Das Modell basiert auf der Grundlage der drei lokalen Energiebilanzgleichungen, welche mit der Laplace-Transformation gelöst werden, für die schrittweise Änderung der primären Fluideintrittstemperatur. Lösungen wurden für den Fall gefunden, daß die Anfangsbedingungen konstant sind und werden in der expliziten Schreibweise ausgedrückt, um die Temperaturverteilungen der beiden Fluide und der Wand genauso gut zu erhalten wie die Fluidgemischtemperaturen am Ausgang. Die dargestellten Lösungen sind für den Fall gültig, daß die Fluidgeschwindigkeiten verschieden oder gleich bzw. endlich oder unendlich sind. Diese Lösungen können für mathematische Modellsysteme, die diese Typen des Wärmeaustauschers beinhalten, sehr geeignet sein.

Research paper thumbnail of Compressed Air System

John Wiley & Sons, Ltd eBooks, Mar 18, 2009

Research paper thumbnail of Analytical Solution of the Transient Response of Gas-to-Gas Crossflow Heat Exchanger With Both Fluids Unmixed

Journal of heat transfer, Nov 1, 1986

The dynamic response of a single-pass crossflow heat exchanger with both fluids unmixed to arbitr... more The dynamic response of a single-pass crossflow heat exchanger with both fluids unmixed to arbitrary time varying inlet temperatures of fluids is investigated analytically. The initial spatial temperature distribution of the heat exchanger core is arbitrary as well. Analytical solutions for temperature distributions of both fluids and the wall as well as the mean mixed fluid temperatures at the exit are presented. The solutions are found by using Laplace transform method and special functions in the form of series of modified Bessel functions.

Research paper thumbnail of Sustavno gospodarenje energijom i upravljanje utjecajima na okoliš u industriji

Research paper thumbnail of Analytical Solution of Transient Response of Gas-to-Gas Parallel and Counterflow Heat Exchangers

Journal of heat transfer, Nov 1, 1987

This paper shows how the transient response of gas-to-gas parallel and counterflow heat exchanger... more This paper shows how the transient response of gas-to-gas parallel and counterflow heat exchangers may be calculated by an analytical method. Making the usual idealizations for analysis of dynamic responses of heat exchangers, the problem of finding the temperature distributions of both fluids and the separating wall as well as the outlet temperatures of fluids is reduced to the solution of an integral equation. This equation contains an unknown function depending on two independent variables, space and time. The solution is found by using the method of successive approximations, the Laplace transform method, and special functions defined in this paper.

Research paper thumbnail of Experimental prediction of heat transfer coefficients by use of a double-blow method

Wärme- und Stoffübertragung (Zeitschrift. 1968), Jun 1, 1994

A new method is proposed for evaluating heat transfer coefficients in a heat exchanger matrix. In... more A new method is proposed for evaluating heat transfer coefficients in a heat exchanger matrix. In comparison with the well known single-blow method, a new double-blow method offers prediction of heat transfer coefficients on both sides of the heat exchanger wall by using one run only, because temperatures of both fluids flowing through the heat exchanger matrix are changed and measured.The experimental technique, data collection procedure, and the method of analysis are derived from an analysis of the analytical solution of the transient response of gas-to-gas cross flow heat exchanger with finite wall capacitance.ZusammenfassungZur Ermittlung von Wärmeübergangskoeffizienten in einer Wärmetauschermatrix wird ein neues Verfahren vorgeschlagen. Im Vergleich mit der wohlbekannten Einzelbeaufschlagungsmethode ermöglicht ein neues Doppelbeaufschlagungsverfahren die Ermittlung von Wärmeübergangskoeffizienten auf beiden Seiten der Wärmetauschertrennwand in nur einem Versuchslauf, da die Temperaturen beider, den Wärmetauscher durchströmenden Medien gemessen werden.Die experimentelle Technik, das Datenkollokationsverfahren und das Berechnungsverfahren wurden ausgehend von der analytischen Lösung für das Übertragungsverhalten eines Gas/Gas-Kreuzstrom-Wärmetauschers mit endlicher Wärmekapazität der Wand entwickelt bzw. abgeleitet.

Research paper thumbnail of Industrial Steam System

John Wiley & Sons, Ltd eBooks, Mar 18, 2009

This chapter contains sections titled: System Description System Performance Definition Principle... more This chapter contains sections titled: System Description System Performance Definition Principles of Performance Analysis Analysis of Boiler Performance Factors Influencing Boiler Performance Opportunities for Boiler Performance Improvement Software for Boiler Performance Analysis Boiler Performance Monitoring Steam Distribution and Condensate Return System Condensate Return System Environmental Impacts Bibliography ]]>

Research paper thumbnail of Nonlinear transient temperature field in a hexagon

Ingenieur-Archiv, 1980

SummaryAn approximate direct method for solving nonlinear transient heat conduction problem in th... more SummaryAn approximate direct method for solving nonlinear transient heat conduction problem in the hexagon, based on Gauss' principle of least constraint is presented. The problem is reduced to the algebraic minimization of a quadratic form with respect to the physical components of the temporal and spatial changes of temperature field. For various values of specific heat and thermal conductivity temperature coefficients the comparison of approximate solutions with the numerical ones is performed and an agreement is found.ÜbersichtEs wird eine auf dem Gaußschen Prinzip des kleinsten Zwanges gegründete direkte Näherungsmethode für die Lösung nichtlinearer instationärer Wärmeleitungsprobleme dargestellt. Das Problem wird auf die algebraische Minimisation einer quadratischen Form bezüglich der physikalischen Parameter der Zeit- und Raumvariablen des Temperaturfeldes zurückgeführt. Die Lösung wird für verschiedene Werte der Temperaturkoeffizienten, der spezifischen Wärmekapazität und der Wärmeleitfähigkeit mit der numerischen Lösung verglichen, wobei eine gute Übereinstimmung erreicht wird.

Research paper thumbnail of Analytical solution for transient response of counter flow heat exchanger with finite wall capacitance

Wärme- und Stoffübertragung (Zeitschrift. 1968), Jun 1, 1993

Research paper thumbnail of Analytical Solution of Dynamic Response of Heat Exchanger

InTech eBooks, Mar 9, 2012

Heat Exchangers-Basics Design Applications 54 in which both fluids are gases. The paper (Gvozdena... more Heat Exchangers-Basics Design Applications 54 in which both fluids are gases. The paper (Gvozdenac, 1987) shows analytical solution for transient response of parallel and counter flow heat exchangers. However, these solutions are limited to the case in which heat capacities of both fluids are negligibly small in relation to the heat exchanger's separating wall capacity. Moreover, it is important to mention that papers (Romie, 1983), (Gvozdenac, 1986), (Spiga & Spiga, 1987) and (Spiga & Spiga, 1988) deal with two-dimensional problems of transition for cross flow heat exchangers with both fluids unmixed throughout. The last paper is the most general one and provides opportunities for calculating transient temperatures of wall temperatures and of both fluids by an analytical method for finite flow velocities and finite wall capacity. The paper (Gvozdenac, 1990) shows analytical solution of transient response of the parallel heat exchanger with finite heat capacity of the wall. The procedure presented in the above paper is also used for resolving dynamic response of the cross flow heat exchanger with the finite wall capacity (Gvozdenac, 1991). A very important book is that of Roetzel W and Xuan Y (Roetzel & Xuan, 1999) which provides detailed analysis of all important aspects of the heat exchanger's dynamic behavior in general. It also gives detailed overview and analysis of literature. This paper shows solutions for energy functions which describe convective heat transfer between the wall of a heat exchanger and fluid streams of constant velocities. The analysis refers to parallel, counter and cross flow heat exchangers. Initial fluids and wall temperatures are equal but at the starting moment, there is unit step change of inlet temperature of one of the fluids. The presented model is valid for finite fluid velocities and finite heat capacity of the wall. The mathematical model is comprised of three linear partial differential equations which are resolved by manifold Laplace transforms. To a certain extent, this paper presents a synthesis of the author's pervious papers with some simplified and improved final solutions. The availability of such analytical solutions enables engineers and designers a much better insight into the nature of heat transfers in parallel, counter and cross flow heat exchangers. For the purpose of easier practical application of these solutions, the potential users are offered MS Excel program at the web address: www.peec.uns.ac.rs. This program is open and can be not only adjusted to special requirements but also modified. 2. Mathematical formulation Regardless of seeming similarity of partial differential equations arising from mathematical modeling, this paper analyzes parallel, cross and counter flow heat exchangers separately. However, simplifying assumptions in the derivation of differential equations are the same and are as follows: a. Heat transfer characteristics and physical properties are independent of temperature, position and time; b. The fluid velocity is constant in each flow passage; c. Axial conduction is negligible in both fluids and the wall; d. Overall heat losses are negligible; e. The heat generation and viscous dissipation within the fluids are negligible; f. Fluids are assumed to be finite-velocity liquids or gases. This means that the fluid transit or dwell times are not small compared to the duration of transience.

Research paper thumbnail of Transient response of the parallel flow heat exchanger with finite wall capacitance

Ingenieur-Archiv, 1990

This paper shows how the transient response of the parallel heat exchanger with finite wall capac... more This paper shows how the transient response of the parallel heat exchanger with finite wall capacitance may be calculated by an analytical method. Making usual idealizations for the analysis of dynamic behavior of the heat exchanger, the model is based on three local energy balance equations which are solved by using ~he Laplace transform method for step change of the primary fluid inlet temperature. The solutions are found in the case of constant initial conditions and expressed in explicit analytical form in terms of the number of transfer units, heat capacity ra~ios, heat transfer resistance and flow capacitance ratios. The presented solutions are valid in cases where fluid velocities are different or equal and finite or infinite. The solutions can be very suitable for the mathematical modeling of systems containing such types of heat exchangers. Das (~bergangsverhalten des Gleichstrom-W~irmetauschers mit endlieher Wiirmekapazit~it der W~nde [~bersieht: Vorgestellt wird eine analytische Berechnungsmethode ffir das Ubergangsverhalten helm Gleichstrom-W~.rmetauscher mit endlicher Wandkapaziti~t. Mit den fiblichen Idealisierungen ffir die Behandlung des dynamischcn Verhaltens yon W~rmetauschern geht die Modellierung aus yon drei lokalcn Energiebilanz-Gleichungen, die mit I-Iilfe der Laplace-Transformation ffir einen Sprung in der Einlauftemperatur des prim~ren Fluids gel6st werden. Die L6sungen, die man ffir konstante Anfangsbedingungen erh~lt, werden in expliziter analytischer Form und in Abhi~ngigkeit yon der Zahl der ~bertragungseinheiten, der Verhiiltnisse der WgrmeinhMte, der W~rmefibergangswiderstiinde and Durchflugkapazitgten dargestellt. Die angegebenen LSsungcn gelten fiir gleiche und verschiedene sowie endliche oder unendliche Str6mungsgeschwindigkeiten.

Research paper thumbnail of Relationship between Energy Use and Production Volume

John Wiley & Sons, Ltd eBooks, Mar 18, 2009

This chapter contains sections titled: Introduction Energy/Production Relationship by Design Ener... more This chapter contains sections titled: Introduction Energy/Production Relationship by Design Energy/Production Relationship by Standard Operational Procedure Presenting the Dynamics of the Energy/Production Relationship by Scatter Diagram Interpretation of Energy/Production Data Pattern on the Scatter Diagram Statistical Methods for Energy/Production Variability Analysis Meaning and Use of the Regression Line in Energy Performance Evaluation Summary of Presenting and Analyzing the Energy/Production Relationship Bibliography

Research paper thumbnail of Performances of Three-Fluid Single Pass Crossflow Heat Exchanger

Research paper thumbnail of Systematic management of energy and environmental impacts in the industry

Knjiga „Sustavno gospodarenje energijom i upravljanje utjecajima na okolis u industriji“ pruža op... more Knjiga „Sustavno gospodarenje energijom i upravljanje utjecajima na okolis u industriji“ pruža opsežan pregled problematike energetske efikasnosti i utjecaja na okolis s naglaskom na primjenu tehnickih i menadžerskih rjesenja za povecanje energetske efikasnosti industrijskih postrojenja Ova knjiga ce sigurno biti i dobar sveucilisni udžbenik za studente, ali i odlicna strucna podloga svim ljudima koji brinu o potrosnji energije i utjecajima na okolis u industrijskim pogonima i ciji je cilj kontinuirano poboljsavanje energetske efikasnosti i smanjenje stetnih emisija u okolis.

Research paper thumbnail of The Influence of Power Loss Coefficient and Other Factors to the Primary Energy Saving of a Cogeneration Power Plant in Thailand

For CHP plants which include fully or partially condensing steam turbine, electrical/mechanical e... more For CHP plants which include fully or partially condensing steam turbine, electrical/mechanical electricity generation will decline as steam extraction increases for a given fuel energy consumption, hence there needs a balance between increasing heat energy recovery and reducing electrical/mechanical energy output assuming a constant fuel energy input. Through a daily energy supply data over a year in one of the cogeneration power plants in Thailand, the influence of power loss coefficient to Primary Energy Saving (PES) or efficiency is analyzed. Power loss coefficient used in the calculations was defined as per the basic theory of power loss coefficient in CHP Manual by EU Parliament and CHP Methodology by UNFCCC. Calculation of saving of primary energy according using cogeneration system follows the EU Manual; setting of CHP overall efficiency must be same with overall efficiency of power plant. Power loss coefficient just makes senses for calculation of power generated by CHP mod...

Research paper thumbnail of A Mathematical Model for Heat Transfer in Combustion Chambers of Steam Generators

Journal of Engineering for Power, 1981

This paper describes a mathematical model for determining the total heat transfer in combustion c... more This paper describes a mathematical model for determining the total heat transfer in combustion chambers of steam generators. The model is based on the energy balance of radiation in a spherical combustion chamber which is divided into a combustion zone and gaseous zone. The model was tested on a Hewlett-Packard Type 9815 A computer with 2008 program memories. Calculations were made for a number of steam generator combustion chambers of different furnace loads for which all important factors were established. The model allows a didactic analysis of factors influencing the process of combustion and heat transfer.

Research paper thumbnail of Applied Industrial Energy and Environmental Management

Applied Industrial Energy and Environmental Management, 2008

Boiler feed water (suction) 0.5-1.0 6. Boiler feed water (discharge) 1.5-2.5 7. Condensate 1.0-2.... more Boiler feed water (suction) 0.5-1.0 6. Boiler feed water (discharge) 1.5-2.5 7. Condensate 1.0-2.0 8. Circulation of hot water 1.0-3.0 STEAM 9. High pressure saturated steam 25-40 10. Medium and low pressure saturated steam 30-40 11. Saturated seam at peak load up to 50 12. Wet steam up to 25 13. Superheated steam 50-100 OIL 14. Suction line of pump up to 0.5 16. Suction line of pump (low pressure) 0.1-0.2 17. Discharge line of booster pump 1.0-2.0 18. Discharge line of burner pump up to 1.0 AIR AND SIMILAR GASES 19. Combustion air duct 12-20 20. Air inlet to boiler house 1.0-3.0 21. Compressed air pipes 20-30 22. Air with natural draft 2.0-4.0 23. Ventilation ducts (hospitals, theaters, etc.) 1.8-4.0 24. Ventilation ducts (office buildings, etc.) 2.0-4.5 EXHAUST GAS 25. Ducts at minimum load up to 4.0 26. Stack at minimum load up to 5.0 27. Boiler with one-step burner (on-off) 5.0-8.0 28. Boiler with two-step burner (high-low) 10-15 29. Boiler with modulating burner (3:1) 15-25 To keep the surface free of soot, the velocities should always exceed 3.0-4.0 m/s

Research paper thumbnail of Condensation intensity in vapour/gas mixture

W�rme - und Stoff�bertragung, 1993

Research paper thumbnail of Performances of three-pass crossflow heat exchangers: Inverted order flow arrangements

Wärme- und Stoffübertragung, 1994

ABSTRACT