Mathematical modelling of the transient response of pipeline

Taler, Dawid; Kaczmarski, Karol

doi:10.1007/s11630-016-0897-0

Cited by 25 publications

(22 citation statements)

References 3 publications

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“…The value of heat transfer coefficient significantly affects the value of the thermal stress [5]. Time changes in optimum fluid temperature determined from the condition of not exceeding the stress at a point lying on the inner surface of the pressure component, very strong depend on the heat transfer coefficient [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Simple heat transfer correlations for turbulent tube flow

Taler

2017

E3S Web Conf.

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Abstract. The paper presents three power-type correlations of a simple form, which are valid for Reynolds numbers range from 3·10 3 ≤ Re ≤ 10 6 , and for three different ranges of Prandtl number: 0.1 ≤ Pr ≤ 1.0, 1.0 < Pr ≤ 3.0, and 3.0 < Pr ≤ 10 3 . Heat transfer correlations developed in the paper were compared with experimental results available in the literature. The comparisons performed in the paper confirm the good accuracy of the proposed correlations. They are also much simpler compared with the relationship of Gnielinski, which is also widely used in the heat transfer calculations.

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Section: Introductionmentioning

confidence: 99%

Simple heat transfer correlations for turbulent tube flow

Taler

2017

E3S Web Conf.

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“…These correlations are appropriate only for high Reynolds numbers when the Rew is larger than 4000. Recently, Taler [8][9] proposed a new correlation to calculate the Nusselt number for the transitional and turbulent fluid flow inside the tubes at a given tube surface temperature or constant heat flux. In this paper, theoretical and empirical relationships were found.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, theoretical and empirical relationships were found. The tube-side heat transfer correlations proposed in [8,9] were generalized to account that transitional flow begins at Rew,trb and ends at Rew,tre. It was assumed in [8,9] that Rew,trb = 2300 and Rew,tre = 3000.…”

Section: Introductionmentioning

confidence: 99%

“…The tube-side heat transfer correlations proposed in [8,9] were generalized to account that transitional flow begins at Rew,trb and ends at Rew,tre. It was assumed in [8,9] that Rew,trb = 2300 and Rew,tre = 3000. However, the experimental results obtained by Ghajar et al [10] and Meyer and co-workers [11] showed that the values of Rew,trb and Rew,tre can differ from the values 2300 and 3000, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Performance of Air-Cooled Heat Exchanger with Laminar, Transitional, and Turbulent Tube Flow

Taler

2018

MATEC Web Conf.

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Some air-cooled heat exchangers, especially in air conditioning and heating installations, heat pumps, as well as car radiators, work in a wide range of loads when the liquid flow in the tubes can be laminar, transitional or turbulent. In this paper, a semi-empirical and empirical relationship for the Nusselt number on the liquid-side in the transitional and turbulent range was derived. The friction factor in the transition flow range Rew,trb ≤ Rew ≤ Rew,tre was calculated by linear interpolation between the values of the friction factor for Rew,trb =2,100 and Rew,tre =3,000. Based on experimental data for a car radiator, empirical heat transfer relationships for the air and water-side were found by using the least squares method. The water temperature at the outlet of the heat exchanger was calculated using P-NTU (effectiveness-number of transfer units) method. The heat flow rate from water to air was calculated as a function of the water flow rate to compare it with the experimental results. The theoretical and empirical correlation for the water-side Nusselt number developed in the paper were used when determining the heat flow rate. The calculation results agree very well with the results of the measurements.

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“…This is difficult to achieve in practice as this state settles in the pressure element wall only after it has been heated at a constant rate for 20-30 minutes. Due to high rates of changes in steam temperatures in time, the quasi-stationary temperature field is very seldom to occur [7,8]. Moreover, the element heating and cooling times determined based on the TRD-301 regulations or the EN 12952-3 standard can cause excessive stress on the edges of the holes.…”

Section: Introductionmentioning

confidence: 99%

New start-up curves for a 200 MW steam boiler with natural circulation

Dzierwa

2018

MATEC Web Conf.

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The paper shows the method of determining the start-up curves of a steam boiler, which enables its faster start-up. Faster temperature changes cause thermal stress, especially in thick-walled boiler elements. Critical elements that limit the rate of change of working fluid units include drums, outlet chamber, injection chamber, fresh steam superheater of steam coolers, tees and valve casings, rotor and turbine casing. The walls of these elements have the thickest walls due to the high pressure values occurring in them during operation. Allowable changes in temperature and pressure during start-up and shut-down can be determined by the European Standard EN 12952-3. The article shows how the start-up curves of a steam boiler can be determined using the European Standard and the method proposed by the author. Calculation results show that the starting time of the analyzed block can be significantly shortened.

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Mathematical modelling of the transient response of pipeline

Cited by 25 publications

References 3 publications

Simple heat transfer correlations for turbulent tube flow

Simple heat transfer correlations for turbulent tube flow

Performance of Air-Cooled Heat Exchanger with Laminar, Transitional, and Turbulent Tube Flow

New start-up curves for a 200 MW steam boiler with natural circulation

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