Influence of coolant flow rates on the heat exchanger parameter at variable operation modes

Rafalskaya, Tatyana; Rudyak, V. Ya.

doi:10.22227/1997-0935.2019.5.621-633

Cited by 4 publications

(2 citation statements)

References 14 publications

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“…Преимущественное использование именно пластинчатого теплообменного оборудования по отношению к кожухотрубному объясняется компактностью их конструкции (по габаритным размерам) и высокой тепловой эффективностью [10,11]. В то же время относительно близкий уровень востребованности кожухотрубных теплообменников [7,10,11,12], формирует понимание того, что пластинчатые теплообменные аппараты далеко несовершенны в своем исполнении и требуют дополнительного улучшения собственных эксплуатационных характеристик [13][14][15].…”

Section: Financingunclassified

Thermal Condition in the Channels of Plate Heat Exchangers

Elistratova

Seminenko

Uvarov

2023

Proceedings of the SWSU

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Equipping heat points with plate-type heat exchangers is an integral structural element of the 3rd generation heat and power network and a component of the reliability of the heat supply system as a whole. It has been established that the optimization calculations of heat exchangers of this type are difficult due to the absence of dependences on heat transfer and hydraulic resistance between the channels in the structural space of the heat exchanger.Purpose of research. To clarify the method of calculating plate heat exchangers, excluding the equality of thermal and hydraulic conditions from the generally accepted assumptions.Methods. The research methodology is based on the use of the law of conservation of mass in order to determine the temperature parameters of working fluids in each channel. The solution of this problem is proposed in the form of a system of equations, each of the equations of which characterizes the thermal balance of the channel under consideration. A computer model of the heat exchanger is constructed in order to conduct a numerical study of the thermal regime of the heat exchanger.Results. It is indicated that as an assumption in the well-known mathematical model for calculating the thermal regime of a plate-type heat exchanger, the condition of equal distribution of fluid flows between channels is accepted. This restriction leads to equalization of liquid temperatures in each channel. Taking into account the geometric arrangement of the channels, the excess of the final temperature of the heating and heated coolant in the first and last channels with respect to known data is up to 10%. The results of the study confirm the hypothesis of uneven heating of the coolant along the length of the plate package due to the uneven flow distribution between the channels.Conclusion. The results of analytical calculation and modeling in the SolidWorks environment of the temperature regime in the channels of a plate-type heat exchanger indicate a significant influence of the geometric arrangement on the thermal regime in the channels. The formulated provisions of the mathematical description of the unevenness of the thermal regime of heat exchange channels, taking into account the location of the plates, are recommended to be used when improving the design parameters of plate-type heat exchangers.

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Section: Financingunclassified

Thermal Condition in the Channels of Plate Heat Exchangers

Elistratova

Seminenko

Uvarov

2023

Proceedings of the SWSU

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“…The analysis of various variable modes of operation of heat exchangers, performed in [13], made it possible to obtain a formula describing the change in the heat exchanger parameter in variable mode [14]:…”

Section: Predict Of Return Network Water Temperaturementioning

confidence: 99%

Problems of energy efficiency of heat supply systems

Rafalskaya

2019

E3S Web Conf.

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The main task of energy-efficient heat supply is to ensure full compliance between the produced and consumed thermal power, subject to a minimum of reduced costs. To achieve this goal, various methods of central and local regulation are applied. Analysis of the thermal schemes of some cities in Russia showed that most of the heat sources of centralized heat supply systems are not able to support the design hightemperature graphs with central regulation. Therefore, the area of centralized qualitative method of regulation of heat load has decreased substantially. A perspective direction for the further development of heat supply systems is to appeal to the experience of foreign countries, i.e. the use of qualitative-quantitative and quantitative methods of central regulation and low-temperature heat supply. There is also an acute problem of the complete use of heat by consumers, since overstating of the temperature of the return water substantially reduces the efficiency of heat sources. A new formula has been obtained which makes it possible to predict the temperature of the return network water in variable operating modes of heating points. The resulting formula can be used to set up programmable regulators and will allow correcting irrational modes of operation of heat supply systems.

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Influence of scale deposits on the temperature conditions in the channels of plate-type heat exchangers

2023

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Introduction. At the present stage of development of the heat supply system, the transfer from shell-and-tube constructions to the plate version of heat exchange apparatus is observed. Their main advantages are compactness and efficiency.The main operational problem is the fouling of the inter-plate channels as a result of which the thermal efficiency decreases and operational costs increase. The aim of the work is to establish the dependence of fouling and individual hydraulic conditions in each channel on the temperature regime of a plate-type heat exchanger. Since this issue in the theory of heat exchange apparatuses is not well studied in and has significant assumptions, the diagnosis of fouling of channels is incorrect. Materials and methods. The theory of resistance characteristics of hydraulic systems is used to determine the hydrodynamic mode of plate-type heat exchange apparatus. The temperatures of heating and heated heat carriers at the outlet of each heat exchange channel are determined on the basis of the mass conservation law. This method made it possible to use the results of hydrodynamic calculation of resistance characteristics to calculate the temperature conditions of a plate heat exchange apparatus along the length of the plate pack, including the effect of scale deposits. The validity of the proposed methods was determined by comparing the Pearson’s and Student’s criteria with the results of computer modelling. Results. The dependence between final temperatures of the coolant at outlet of channels depending on the flow distribution of the coolant, taking into account channel impurity was found. The application of the theory of resistance characteristics to calculate the thermal-hydrodynamic mode of the plate heat exchanger and the proposed calculation of the thermal regime, including taking into account the factor of fouling, will improve the accuracy of pollution diagnosis and reduce operating losses. Conclusions. The conducted research confirms the influence of fouling of heat-exchange apparatuses and individual hydraulic conditions of inter-plate channels on the temperature regime. Results of research represent scientific and practical interest at studying and development of the intensified surfaces of heat exchange with the purpose of increase of power indicators of heat-exchange apparatuses, and also in the field of diagnostics of mode parameters of water-heating equipment in the period of its operation.

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Influence of coolant flow rates on the heat exchanger parameter at variable operation modes

Cited by 4 publications

References 14 publications

Thermal Condition in the Channels of Plate Heat Exchangers

Thermal Condition in the Channels of Plate Heat Exchangers

Problems of energy efficiency of heat supply systems

Influence of scale deposits on the temperature conditions in the channels of plate-type heat exchangers

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