Olga Arsenyeva

22033364500

Publications - 5

Heat transfer intensification in compact heat exchangers with channels of various geometries and size

Olga Arsenyeva Petro Kapustenko Leonid Tovazhnyanskyy Petar Sabev Varbanov

Publication Name: International Communications in Heat and Mass Transfer

Publication Date: 2025-09-01

Volume: 167

Issue: Unknown

Page Range: Unknown

Description:

The need to decrease the sizes and masses of heat exchangers while preserving their performance has stipulated the development in compact heat exchangers (CHEs). It is supported by the additional push from process industries for increased recuperation of heat energy, facilitating better energy efficiency in process plants with strict limitations for space, material and cost. The adequate substitution of conventional heat exchangers by CHE in the same process conditions requires maintaining the same heat load not exceeding the allowable pressure losses. The different ways to increase the compactness of CHE are analysed, including the change of hydraulic diameter of heat exchanger channels, and the use of various methods of heat transfer intensification by changing channel geometry and flow structure. The Nusselt numbers and friction factors correlations for plane tubes, enhanced tubes and channels of plate heat exchangers are compared based on available literature data. A newer form of the core velocity equation is developed, which allows a comparison of the performance of CHE heating surfaces with different enhancement techniques and varying scales in specific process conditions. The results of the calculations illustrate the influence of the channel's hydraulic diameter and length on CHE thermal and hydraulic performance for channels with heat transfer intensification. The recommendations on choosing the best channel geometry and size, depending on specified process conditions and stream nature, are formulated.

Open Access: Yes

DOI: 10.1016/j.icheatmasstransfer.2025.109273

Retrofit Synthesis of Industrial Heat Exchanger Networks with Different Types of Heat Exchangers

Olga Arsenyeva Ákos Orosz Ferenc Friedler

Publication Name: Chemical Engineering Transactions

Publication Date: 2021-01-01

Volume: 88

Issue: Unknown

Page Range: 613-618

Description:

Heat Exchanger Network (HEN) synthesis is a powerful tool for the development of more efficient processes with high utilization of mass and energy resources. The implementation of compact heat exchangers with enhanced heat transfer into the industrial flowsheets can provide more efficient and economically feasible solutions. Plate Heat Exchanger (PHE) is one of established types of enhanced HEs. To estimate possible benefits of that kind of heat transfer enhancement, a mathematical model of PHE, which accounts for different plate types and corresponding corrugations geometry, is used. The integration of this model with the P-graph-based HEN synthesis approach allowed to create the method, which considers different types of heat exchangers. This approach enables to integrate not only conventional shell-and-tube heat exchangers, but also PHEs, which overall heat transfer coefficient is in average 2-3 times higher, during the optimization process of a new or existing HEN. The capabilities of the proposed method are presented via a case study for oil preheat train, where an existing network is retrofitted; first with shell-and-tube heat exchangers only, then with the consideration of both shell-and-tube and plate heat exchangers.

Open Access: Yes

DOI: 10.3303/CET2188102

Selection of Heat Transfer Enhancement Technique for Compact Mini and Micro Heat Exchangers Design

Olga Arsenyeva Petro Kapustenko Andrea Nemet Leonid Tovazhnyanskyy Leonid Tovazhnyanskyy Igor Plazl Petar Sabev Varbanov Zdravko Kravanja

Publication Name: Chemical Engineering Transactions

Publication Date: 2025-01-01

Volume: 120

Issue: Unknown

Page Range: 475-480

Description:

The need to decrease the sizes and masses of heat exchangers while preserving their performance has stipulated the development of compact heat exchangers with mini and micro channels (MCHE). It is supported by the need for increased recuperation of heat energy, facilitating better energy efficiency with strict limitations for space, material and cost. The adequate substitution of conventional heat exchangers with MCHE requires maintaining the same heat load, not exceeding the allowable pressure losses. The different ways to increase the compactness are analysed, including the change of hydraulic diameter, and the use of various methods of heat transfer intensification by changing the channel geometry and flow structure. The Nusselt numbers and friction factors correlations for plane tubes and criss-cross flow channels of plate heat exchangers are compared. A newer form of the core velocity equation has been developed, which allows comparison of the performance of MCHE heating surfaces with different enhancement techniques in specific process conditions. The results of the calculations illustrate the influence of the channel's hydraulic diameter and length on the MCHE performance for channels with the considered methods of heat transfer intensification. The ways to decrease channel size to mini and micro scales are determined. The recommendations on choosing the best channel geometry and size, depending on specified process conditions and stream nature, are formulated.

Open Access: Yes

DOI: 10.3303/CET25120080

Thermal-hydraulic performance of heat exchanger mini- and micro-channels with single-phase flows. A comprehensive review and a comparative study

Olga Arsenyeva Andreja Nemet Petro Kapustenko Ting Pan Leonid Tovazhnyanskyy Boton Bertok Leonid Tovazhnyanskyy Igor Plazl Petar Sabev Varbanov Zdravko Kravanja

Publication Name: Renewable and Sustainable Energy Reviews

Publication Date: 2026-04-01

Volume: 230

Issue: Unknown

Page Range: Unknown

Description:

The efficient use of energy is a prerequisite for the sustainable development of modern society. It requires increasing heat recuperation in various energy-reliant systems, which is possible with heat transfer devices of intensive action, operating in conditions of limited space for installation and material availability for their production. This is achieved by heat exchangers with mini- and micro-channels, regarded as the next generation of heat transfer equipment. A survey of publications on heat transfer and pressure losses in mini- and microchannels is presented, with focus on their thermal-hydraulic performance. It includes straight channels of various cross-sectional forms, channels with enhanced heat transfer for electronic cooling, additively manufactured microchannels, crisscross flow channels of microturbine recuperators, and plate heat exchangers. A novel Micro Heat Factor for the comparison of mini- and microchannels thermal-hydraulic performance is derived. For the detailed estimation of channel performance in specified process conditions, accounting for the differences in hydraulic diameters, the equation for optimal fluid velocity is proposed. The comparison of thermal-hydraulic performance for different types of mini- and micro channels is performed, and the possibilities of their use in heat exchangers at specific applications are discussed, followed by directions of future studies.

Open Access: Yes

DOI: 10.1016/j.rser.2026.116722

Selection of the mini- and micro-channels geometry for improved heat recuperation in specific industrial conditions

Olga Arsenyeva Julia Riese Petro Kapustenko Leonid Tovazhnyanskyy Leonid Tovazhnyanskyy Petar Sabev Varbanov

Publication Name: International Journal of Thermal Sciences

Publication Date: 2026-11-01

Volume: 229

Issue: Unknown

Page Range: Unknown

Description:

The sustainable development of modern society requires the efficient use of energy in industry and in the communal sector. This is possible by increasing heat recuperation and using intensified heat exchangers. Recuperative heat exchangers enable the use of heat from streams exiting high-temperature processes to heat the cold supply streams. They have a lot of applications, such as ammonia and methanol synthesis, high-temperature nuclear reactors, the Brayton power cycle, pasteurisation of food products, etc. A new method for selecting the best channel geometry for specific applications of recuperative heat exchangers is proposed, based on the use of mini- and micro-channels of various types and sizes. It involves the numerical solution of a novel equation developed to evaluate the thermal-hydraulic performance of mini- and micro-channels in certain process conditions. This allows the comparison of performance for channels using different methods of heat transfer enhancement. The new simplified formulas for micro-channel performance evaluation in the laminar flow regime are also proposed. The influence of operating heat load on optimal channel geometry is discussed, and the way to modernise channel parameters specifically for use in micro-process systems. The methodology is illustrated by the example of an industrial application. Compared to macro-channels, the heat transfer area of HE with mini-channels can be reduced by 1.2 to 3 times for intensified mini-channels with a hydraulic diameter of 1 mm, with possible reduction by 3 to 5 times in micro-channels of the hydraulic diameter 0.1 mm. The use of the proposed equation and the correct adjustment of the channel length results in up to 12% smaller heat transfer area with channels of the same geometry. It can be improved by about 37% by selection of a proper channel type.

Open Access: Yes

DOI: 10.1016/j.ijthermalsci.2026.111129