Heat transfer and flow resistance in flow boiling in minichannels of a new fluids with the parameters close to thermodynamic critical point

Complex experimental and theoretical research of flow boiling in channels with low diameters (<3 mm) with parameters close to thermodynamic critical and supercritical point in vertical channels will be conducted. The project anticipates research of three types of media. Measurements of the temperature of the heating surface shall be conducted simultaneously with three different methods, including contact measurement (point by point – thermoelements) and contactless measurement (LCD thermography, thermal vision). In the course of the research, the heat flux delivered to the heating surface will be gradually increased and then decreased through the control of the delivered power which will initiate boiling and its further development. Measurement data will allow the construction of the heating curves, determination of local heat transfer coefficients and local friction coefficients. Planned visualization of the transfer structures will allow the determination of the saturation degree and degree of dryness of the two-phase flux and creation of the maps of the structures of two-phase flux. Systematic cycles of experimental research will allow the determination of the conditions of the appearance and development of boiling in the flow of various media in the function of the set thermal-flow parameters (mass flow, Reynolds number, pressure and underheating of the fluid to the temperature of saturation at the outflow). Special interest shall be taken in the nature of the changes of flow resistance and the values of the degree of saturation (real volumetric share) of liquid and gaseous phase in a two-phase mixture. Collected experimental data shall be used to develop a dedicated theoretical model of the process and to verify own calculation model which has been developed for years within the research team. The research will allow direct observation of physical phenomena occurring during the boiling process and will facilitate creating a complex mathematical description of the development of boiling in minichannels within the range of near-critical parameters. A proprietary, more general calculation model of the process shall be made. Integrated results will contribute to the development of the DSc thesis of Rafał Andrzejczyk, PhD, ME and at least one MSc thesis.

Details

Financial Program Name:: OPUS
Organization:: Narodowe Centrum Nauki (NCN) (National Science Centre)
Agreement:: UMO-2017/25/B/ST8/00755 z dnia 2018-03-05
Realisation period:: 2018-03-05 - 2021-09-04
Project manager:: prof. dr hab. inż. Dariusz Mikielewicz
Realised in:: Department of Energy and Industrial Apparatus
Project's value:: 773 200.00 PLN
Request type:: National Research Programmes
Domestic:: Domestic project
Verified by:: Gdańsk University of Technology

Papers associated with that project

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total: 6

Modelling study of flow boiling heat transfer of perspective fluids for refrigeration technology
Publication
- M. Pysz
- D. Mikielewicz
- Year 2020
There is a gap of knowledge on flow boiling at high saturation temperatures and higher values of reduced pressure. Thus far, the in-house developed semi-empirical model for flow boiling and flow condensation showed a satisfactory accuracy for calculations for various refrigeration fluids for a wide scope of reduced pressures. This study presents results of calculations of heat transfer coefficient of perspective refrigeration fluids,...
Pressure drop and heat transfer during boiling and condensation at subcritical region
Publication
- Year 2020
Most of the data presented in the literature relate to saturation temperatures in the range - 20°C to 40°C due to the application in refrigeration technology. There is necessity to extend databases to higher values of saturation temperature due to new applications such as Organic Rankine Cycle and high temperature heat pumps. Only few papers contain data for high reduced pressure for low boiling point liquids. This paper focus...
Analysis of Organic Rankine Cycle efficiency and vapor generator heat transfer surface in function of the reduced pressure
Publication
- D. Mikielewicz
- J. Mikielewicz
- ENERGY - Year 2022
In the paper presented is analysis of the influence of reduced pressure on efficiency and heat transfer area of vapor generator of Organic Rankine Cycle (ORC) in case of subcritical and supercritical parameters of operation. Compared are two cases of subcritical and supercritical ORC featuring a similar arrangement of heat source supply and heat removal, that is featuring the same temperatures of working fluid before the turbine,...

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An improved method for flow boiling heat transfer with account of the reduced pressure effect
Publication
- B. Jakubowska
- D. Mikielewicz
- Thermal Science - Year 2019
In the paper are presented the results using the authors own model to predict heat transfer coefficient during flow boiling. The model has been tested against a large selection of experimental data to investigate the sensitivity of the in-house developed model. In the work are presented the results of calculations obtained using the semi-empirical model on selected experimental flow boiling data of the refrigerants: R134a, R1234yf,...

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Modelling of heat transfer in supercritical pressure recuperators
Publication
- D. Mikielewicz
- J. Mikielewicz
- ENERGY - Year 2020
In the paper presented is analysis of convective flow heat transfer at supercritical pressure in channels of heat exchanger working in the thermodynamic cycle. The modelling is based on the division of the flow into three regions, namely the heavy fluid, a two phase flow consisting of the heavy and light fluids and finally the light fluid flow. Modelling is concentrated on the region of simultaneous flow of two fluids divided into...

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Flow boiling of R1233zd(E) in a 3 mm vertical tube at moderate and high reduced pressures
Publication
- M. Pysz
- D. Mikielewicz
- EXPERIMENTAL THERMAL AND FLUID SCIENCE - Year 2023
The results of flow boiling of R1233zd(E) in a 3 mm vertical stainless steel tube are presented at moderate and high saturation temperatures. Integral flow characteristics in the form of pressure drop and heat transfer coefficient are discussed for saturation temperatures ranging from 115 to 145 °C (corresponding reduced pressures from 0.2 to 0.7), mass velocity of 800 kg/m2s and heat flux of 20 kW/m2. All of the obtained heat...

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