Condensation Heat Transfer Coefficient Research Articles

Numerical simulation of condensation heat transfer characteristics of R134a at high vapor velocity under different angles

Heat pipe is widely used as an efficient built-in heat exchanger for thermal management of high pulse and heat flux power supplies. Enhanced heat dissipation at the condensing side is an important issue in heat pipe research, where vapor velocity is an essential factor affecting the condensing heat transfer characteristics. This study adopted the CFD method to numerically simulate the condensation heat transfer of R134a flowing in a smooth pipe. The flow condensation heat transfer characteristics, such as film thickness and heat transfer coefficient (HTC), were investigated under vapor velocities v = 20–100 m/s and tube inclinations β =-90–90° Geometric and numerical heat transfer modeling is established in high vapor velocity flow condensation. The error of numerical simulation results and model validation is 10%. The HTC increases rapidly with the change in vapor velocity under 60 m/s, increasing the rate to 0.4. When the vapor velocity exceeds 60 m/s, the growth trend slows to 0.15, 37.5% of the original increase. At high vapor velocities above 60 m/s, the effect of pipe inclination on condensation heat transfer coefficient can be almost negligible. A modified empirical correlation suitable for high vapor velocities is proposed, which has higher predictive accuracy when the vapor velocity exceeds 80 m/s.

The problem of the surface condenser overall heat transfer coefficient determining at high temperatures of cooling water

The article presents a comparison of the real overall heat transfer coefficient, based on thermal tests of the condenser of the steam turbine PT-25-90 KTZ during off-design operation (with a degraded vacuum) and its expected value, calculated via the Metropolitan Vickers formula. The average cooling water inlet temperature was 61.2 °C, average exhaust steam pressure was 0.542 bar during thermal tests. The average deviation of the expected overall condenser heat transfer coefficient from the real value was 27,18%. The calculations showed a higher difference between the real and expected value at the regimes with low cooling water velocity and with high exhaust stem pressure. The obtained results showed the need to refine the methodology of the condenser's overall heat transfer coefficient calculation in the degraded vacuum mode. This can be done by adding correction factors to the water temperatures that are typical for the degraded vacuum regime.

Experimental study on the correlation between bubble heat transfer coefficient and pressure oscillation frequency in the bubbling regime of steam jet

Direct contact condensation of steam–water is widely applied in the industrial and food fields. In this work, the bubble condensation pressure oscillation frequency and heat transfer coefficient in vertical upward and downward directions are studied. The steam mass flux range is 22.12–50.13 kg m−2 s−1, and the water subcooling degree is 20–40 K. The bubble heat transfer coefficient and the pressure oscillation frequency have a positive correlation in the two steam jet directions. The mechanism of the positive correlation is analyzed. An artificial neural network model is proposed to calculate the bubble heat transfer coefficient. The proposed model can accurately predict the bubble heat transfer coefficient with correlation coefficient R2 = 0.97, which provides a convenient path for obtaining the coefficient of heat transfer.

Heat transfer enhancement of actively-adjusting liquid–vapor in a double-row microchannel condenser

A novel double-row microchannel condenser used the actively-adjusting liquid–vapor mechanism and is then called the double-row liquid–vapor separation microchannel condenser (DLSMC). This study theoretically calculates the condensation heat transfer coefficient (HTC) and the pressure drop and ranks the in-tube thermodynamic performance of the DLSMCs. Then, the thermodynamic performance of the optimal DLSMC and a double-row parallel microchannel condenser (DPFMC) is studied experimentally. Results show that the tube number of a path affects the thermodynamic performance of the DLSMC, and the in-tube entropy generation difference between the optimal DLSMC and the other DLSMCs are approximately 0.7%–2.6%. Compared with the theoretical in-tube entropy generation of the DLSMC, the experimental in-tube entropy generation of the DLSMC is 0.9%–2.7% larger. Compared with the experimental in-tube entropy generation of the DPFMC, the experimental in-tube entropy generation of the DLSMC is 1.3%–4.4% lower. In addition, the HTC and the pressure drop of the first row are approximately 7.7%–9.5% and 13.3%–20.0% lower than those of the second row, respectively, indicating that both rows have different thermodynamic performance.

Laser Textured Superhydrophobic SiC Ceramic Surface and the Performance of Condensation Heat Transfer

Chemical modification is usually utilized for preparing superhydrophobic SiC surfaces, which has the problems of long processing time, high environmental contamination risk, and high cost. To enhance the condensation heat transfer efficiency of SiC, the superhydrophobic SiC surface was fabricated through laser texturing and heat treatment. In this study, the SiC surface was processed by laser texturing with a nanosecond laser, followed by heat treatment. Surface microstructures and compositions were investigated with SEM and XPS, and the heat transfer coefficient of the superhydrophobic SiC surface was tested. The results indicated that the laser-textured SiC surface had a super hydrophilic contact angle of 0°; after heat treatment, SiC ceramic became superhydrophobic (surface contact angle reaches 164°) because organic contamination on the original SiC surface could be cleaned by using laser texturing, which caused a chemical reaction and the formation of SiO2 on the surface. Moreover, the distribution of relatively low-energy SiOX was formed after heat treatment; then, SiC ceramic became superhydrophobic. Due to the formation of nanoscale sheet-like protrusion structures by heat treatment, the SiC superhydrophobic surface exhibited typical dropwise condensation, and the condensation heat transfer coefficient reached 331.8 W/(m2·K), which was 2.3 times higher than that of the original surface.

Experimental study on wet gas condensation heat transfer and flow resistance in horizontal intensified tube

The heat transfer and flow resistance characteristics of in-tube vapor condensation with high content non-condensable gas is significant for designing waste heat recovery devices of gas-fired boilers. In this paper, the forced convection condensation of wet gas in the horizontal tube is experimentally investigated with a non-condensable gas mass fraction of 83–95%. The condensation heat transfer coefficient, thermal resistance and pressure drop are compared between bare tube and two intensified tubes, i.e., the corrugated and spiral tube, under various Reynolds number, wall subcooling degree and inlet humidity. The results show that the in-tube condensation heat transfer coefficient increases with increasing Reynolds number and inlet humidity, but decreases with increasing wall subcooling degree. Compared with the bare tube, the heat transfer coefficient and pressure drop increase up to 47.13% and 16.00% respectively for the spiral tube, and 116.04% and 88.48% respectively for the corrugated tube. When combing the heat transfer and flow resistance factors, the maximum comprehensive performance coefficients are 1.71 and 1.44 for corrugated tube and spiral tube respectively. The superiority of corrugated tube in the wet gas condensation is benefit from effective breaking the non-condensable gas film and promoting the vapor diffusion on the interface.

Numerical Study of Steam–CO2 Mixture Condensation over a Flat Plate Based on the Solubility of CO2

In order to successfully study the condensation and separation of a steam–CO2 mixture, a boundary layer model was applied to the mixture condensation of steam and CO2 on horizontal and vertical plates. The modified condensation boundary layer model of steam and CO2, given the CO2 solubility in the condensate, was established, numerically solved, and verified with existing experimental data. Different condensation data of steam–air and steam–CO2 mixtures were compared, and the effect of CO2 solubility on the mixed gas condensation was analyzed under multiple pressure conditions (1 atm–10 MPa). The simulation data show that the presence of CO2 will deteriorate the condensation heat transfer, just like air. Given that CO2 is slightly soluble, some CO2 can pass through the gas–liquid interface to enter the condensate film and reduce the accumulated CO2 on the gas–liquid interface, which improves the condensation. However, the solubility of CO2 is only significant under high-pressure conditions, inducing its effects on condensation. A comparison of the condensation coefficients of the steam–CO2 mixture shows the lower impact of CO2 condensation on the horizontal plate compared to that on the vertical plate. For most conditions, the steam–CO2 mixture gas condensation heat transfer coefficient on the vertical plate surface is still larger than that on the horizontal plate surface, and the improvement in the condensation heat transfer coefficient caused by low CO2 solubility (2 or 10%) at 10 MPa on the vertical plate is also larger than that of the horizontal plate.

Prediction of heat transfer coefficient and pressure drop of R1234yf and R134a flow condensation in horizontal and inclined tubes using machine learning techniques

Machine learning techniques have great potential to predict two-phase flow characteristics instead of classic empirical correlations. In the present study, four different machine learning models, including multi-layer perceptron artificial neural network (ANNMLP), support vector regression (SVR), K nearest neighbors (KNN), and extreme gradient boosting (XGBoost), are employed to predict the heat transfer coefficient (HTC) and the frictional pressure drop (FPD) of R134a and R1234yf condensation flow in horizontal and inclined tubes. The dataset includes 348 points from previous works and the current research. To extend the data, an experimental study is also performed on the condensation of R134a in a horizontal tube for different mass velocities and vapor qualities. The results show that, in the best model, HTC can be estimated by ANNMLP with the mean absolute percentage error (MAPE) of 7.01%. The best prediction of FPD is achieved using XGBoost machine with MAPE of 10.87% on test data. Also, the feature importance procedure is implemented to recognize the most useful features. Based on the results, the mass velocity and the inclination angle are identified as the most influencing parameters on the prediction of HTC and FPD, respectively.

Micro-grooved circular miniature heat pipe for thermal management: Experimental and analytical investigations

In this paper, thermal performance of a cylindrical micro-grooved heat pipe is experimentally and mathematically investigated. The experimental tests are conducted included the optimum working fluid filling ratio, heat pipe inclination, and input heat load. The new correlations of micro-grooved heat pipe condensation and evaporation heat transfer coefficients are proposed basing on the experimental data. A coupled thermal and hydraulic model is developed to predict the heat pipe local thermal resistances and operating temperature regarding the effect of the architectural size. The Experimental results show that the heat pipe thermal performance is not affected by the inclination angle. Whereas the heat pipe performance is better at horizontal position. It showed that the micro-grooved heat pipe could provide an efficient performance even if the condenser is longer that 40% of the total length and the heat pipe microgrooves aspect ratio higher than 37%.

Condensation characteristics of air–water vapor mixture on the surface of vertical flat plate

The condensation heat transfer of air–water mixed vapor is an important heat transfer phenomenon in production life. An experimental system for condensation heat transfer of the air–water vapor mixed vapor is built in this paper. The condensation characteristics of the mixed vapor and the double boundary layer structure characteristics were investigated. The study mainly discussed the influence of flow velocity on the condensation performance of mixed vapor and summarized the experimental correlation equations considering flow velocity. Results indicate that the condensation performance decreases significantly as the air concentration increases. The mixed vapor flow velocity was increased from 1 to 3 m/s, and the condensation heat transfer coefficient was increased by 34.9–121.0%. The enhanced effect of flow velocity was also observed at high air concentration and low subcooling. The ratio of convective and condensation heat transfer coefficients increases with the rise in air concentration, reaching a maximum of 0.12. The proportion of convective heat transfer can be reduced by increasing the mixed vapor flow velocity. The gas film thickness is substantially higher than the liquid film thickness in mixed vapor condensation, and the gas/liquid film thermal resistance ratio can be more than 30 times. And increasing the flow velocity can significantly reduce the gas film/liquid film thermal resistance ratio. A new experimental correlation equation is fitted based on the experimental results, and this equation can be used as a reference for the design of related heat exchangers.

Experimental study on condensation heat transfer characteristics in C-shaped tube under rolling conditions

C-shaped tube heat exchanger has the advantages of good performance in heat transfer, space-saving, and reliability, and thus it has great potential to be used as passive residual heat removal heat exchanger in offshore nuclear power plants. In the present study, the condensation heat transfer characteristics in a C-shaped tube, which is the basic unit of C-shaped tube heat exchanger, were investigated experimentally, and the experiment was carried out under steady state and rolling conditions respectively. The effect of heat flux and rolling conditions on the condensation heat transfer characteristics were studied. The heat flux varies from 73.3 kW/m2 to 446.7 kW/m2; the rolling amplitude varies from 5° to 15°; and the rolling period ranges from 5 s to 20 s. The experimental results show that the condensation in the C-shaped tube is gravity-dominated. Based on the experiment data, a new correlation used to calculate the heat transfer coefficient of a C-shaped tube under steady state has been obtained. The rolling motion has significant effect on the condensation heat transfer of the C-shaped tube. With the increase of rolling angle from 0° to 15°, the condensation heat transfer performance of the C-shaped tube gradually increases and the increase rate of the condensation heat transfer coefficient is up to 18%. On the other hand, with the increase of rolling period from 5 s to 20 s, the condensation heat transfer performance of the C-shaped tube decreases. Further investigation revealed that, as the heat flux increases, the effect of rolling motion on the condensation heat transfer decreases.

Experimental and Simulation Study on the Direct Contact Condensation of Saturated Steam on Moving Droplets at Sub-Atmospheric Pressure

The recovery of low-temperature steam is of great significance to the effective utilization of energy. Direct contact condensation (DCC) technology is an effective heat recovery method with a low initial investment. An evaluation of the direct contact condensation heat transfer technology of water droplets and low-temperature saturated steam (at an absolute pressure of 7.3–19.9 kPa) was performed using both experimental and computational approaches. In the experiment, an experimental device based on the weighing method was set up, and the direct contact heat transfer process between droplets with a normalized diameter of less than 21.7 and saturated pure steam at 40–60 °C was experimentally investigated. The transient condensation efficiency and heat transfer coefficient were calculated by the real-time mass variation. The rapid condensation stage was classified to discuss the effects of initial droplet diameter, pressure, temperature, and mass flow rate on the heat transfer process. A two-dimensional model was developed using computational fluid dynamics techniques and verified by experimental results. The results indicated that when the normalized diameter of the droplet is less than two, 1.6 is the optimal value for DCC. For droplets with a normalized diameter greater than two, the optimal droplet temperature and mass flow rate are 15 °C and 10 g/s, respectively.

Study of steam heat transfer enhanced by CO2 and chemical agents: In heavy oil production

Steam flooding with the assistance of carbon dioxide (CO 2 ) and chemicals is an effective approach for enhancing super heavy oil recovery. However, the promotion and application of CO 2 and chemical agent-assisted steam flooding technology have been restricted by the current lack of research on the synergistic effect of CO 2 and chemical agents on enhanced steam flooding heat transfer. The novel experiments on CO 2 -chemicals cooperate affected steam condensation and seepage were conducted by adding CO 2 and two chemicals (sodium dodecyl sulfate (SDS) and the betaine temperature-salt resistant foaming agent ZK-05200). According to the experimental findings, a “film” formed on the heat-transfer medium surface following the co-injection of CO 2 and the chemical to impede the steam heat transfer, reducing the heat transfer efficiency of steam, heat flux and condensation heat transfer coefficient. The steam seepage experiment revealed that the temperature at the back end of the sandpack model was dramatically raised by 3.5–12.8 °C by adding CO 2 and chemical agents, achieving the goal of driving deep-formation heavy oil. The combined effect of CO 2 and SDS was the most effective for improving steam heat transfer, the steam heat loss was reduced by 6.2%, the steam condensation cycle was prolonged by 1.3 times, the condensation heat transfer coefficient was decreased by 15.5%, and the heavy oil recovery was enhanced by 9.82%. Theoretical recommendations are offered in this study for improving the CO 2 -chemical-assisted steam flooding technique.

Experimental analysis of the stimulation mechanism of CO2-assisted steam flooding in ultra-heavy oil reservoirs and its significance in carbon sequestration

In this work, the mechanisms of CO2-assisted steam flooding in ultra-heavy oil reservoir development are discussed. One-dimensional models are established to simulate the reservoirs, and the development characteristics of CO2-assisted steam flooding are studied. The feasibility of this development method in carbon sequestration is verified by analyzing the produced oil components. Subsequently, two-dimensional models are used to create the visual reservoir profiles, observe the fluid distribution in the reservoir, and analyze the influence of CO2 on the steam heat transfer. The results show that the steam sweep efficiency of steam flooding is poor due to the unsatisfactory displacement mobility ratio, heat loss and channeling. The oil recovery is below 50%. However, during CO2-assisted steam flooding, the recovery factor is increased to about 60%. The injected CO2 is expanded by heat, pushing steam deeper into the reservoir. It dissolves in oil to form foam, which alleviates channeling while optimizing steam sweep efficiency. In addition, CO2 can indirectly separate heavy components from oil to reduce its viscosity and improve displacement mobility ratio. Meanwhile, it can reduce the thermal conductivity and the condensation heat transfer coefficient of the medium, reduce the steam heat loss, which allows more heat to travel deeper into the formation. Part of the injected CO2 is stored in the reservoir, with a proportion of 14.39%-17.12%, indicating the potential of CO2-assisted steam flooding in carbon sequestration. Based on the wide source and low cost of CO2, it has advantages in waste gas utilization and heavy oil reservoir development.

Experimental study of coupling heat transfer characteristics of boiling and condensation in an asymmetric phase change chamber

The output power of an automobile exhaust thermoelectric generator can be greatly improved by adding a phase change chamber with the condensation area smaller than the boiling area between the hot side of the thermoelectric modules and the exhaust channel. By decreasing the condensation area, the heat flux through the modules increases, which increases the temperature difference between the hot side and the cold side of the modules. Hence, the output power increases. However, the heat transfer characteristics of such kind of chamber with the confined space, the unequal boiling and condensation areas and the coupling interaction between the boiling and the condensation have not been fully studied. In this paper, the boiling and condensation heat transfer characteristics of deionized water in a chamber with the boiling to condensation area ratio of 5:2 were experimentally studied at boiling heat fluxes from 4.50 kW/m2 to 22.70 kW/m2 and filling ratios from 20% to 70%. The results show that the chamber total thermal resistance decreases and the temperature uniformity increases with increasing heat flux. The filling ratio has little effect on the total thermal resistance. The heat transfer coefficients obtained from the experiments were compared with those predicted by the correlations. The results show that the Cooper correlation (the deviation range of −41.3% ∼ − 9.7% from the experimental results), has a higher accuracy than the Rohsenow correlation (the deviation range of −73.6% to +43.9% from the experimental results) for predicting the boiling heat transfer coefficient. Neither the Nusselt correlation nor the Gerstmann-Griffith correlation can accurately predict the condensation heat transfer coefficients. Besides, the behavior of bubbles and condensate was observed during the experiment, explaining the variations of the boiling and condensation heat transfer coefficients versus heat flux.

Enhanced internal condensation of R1233zd(E) on micro- and nanostructured copper and aluminum surfaces

In-tube condensation of refrigerants is an important process which affects thermal efficiency in many applications, ranging from refrigeration and air conditioning to electronics thermal management. In-tube heat transfer and pressure drop are important to heat exchanger sizing and design. In this work, micro- and nanostructured surfaces are applied to the internal wetted areas of copper and aluminum mini-channels to enhance the condensation heat transfer coefficient of hydrofluorocarbon R1233zd(E) refrigerant. To achieve scalable nanomanufacturing, surfaces were uniformly structured by relying on hydrochloric acid etching of aluminum and chemical oxidation of copper. The etched aluminum surfaces exhibited a 150% increase in heat transfer coefficient compared to smooth aluminum channels at specific qualities, with a 66% heat transfer coefficient improvement for complete phase change from saturated vapor to saturated liquid. Copper oxide structures showed no discernable difference in thermal-hydraulic performance when compared to smooth copper channels. Critical dimensionless parameters governing the heat transfer enhancement were identified by varying the tube internal diameter (2.3 mm to 4.7 mm), refrigerant mass flux (50 to 300 kg/(m2·s)), and refrigerant quality (0 to 1). The dimensionless parameters include the Bond number normalized to the condensate film thickness, and the Weber number modified by the vapor friction factor. The relatively small increase in pressure drop (< 10%) associated with these surface enhancements further supports the promise of this method. The scalable and cost-effective techniques used to create these aluminum microstructures may reduce manufacturing cost when compared with current enhancement approaches such as extrusion, drawing, and welding.

Condensation of R1234yf in a plate heat exchanger with an offset strip fin flow structure for electric vehicle heat pumps

The energy-efficient plate heat exchanger (PHE) and refrigerant R1234yf, which has a low global warming potential (GWP), can be used to realize an energy efficient heat pump (HP) system for electric vehicles (EV), extending their driving range. Therefore, the characteristics of R1234yf in an offset-fin strip (OSF) flow-structured PHE are critical for heat-exchanger design. This study investigates the condensation heat transfer coefficient (C-HTC) and two-phase frictional pressure drop (2P-FPD) of R1234yf during condensation in an OSF flow-structured PHE under various operating conditions. First, a modified Wilson plot method was used to determine the multiplier (C) and Reynolds number exponential (n) for the coolant side as −0.426 and 0.494, respectively. When the heat flux (q), average vapor quality (xa), and mass flux (G) increased, the C-HTC increased, whereas it decreased with saturation temperature (Tsat). Despite the force-convective condensation flow regime, the C-HTC increment was minimal with G at lower xa owing to the lesser significance of the shear effect. Additionally, the 2P-FPD was unaffected by q but increased considerably with an increase in xa and G and a decrease in Tsat. Based on the current experimental database, empirical correlations for forecasting friction factor and Nusselt number were developed with a 91% predictability.

Condensation heat transfer coefficient during steam intermittent flows in a horizontal minichannel

Contents of the paper refer to experimental investigations and subsequent prediction of the heat transfer coefficient for condensation of steam flowing in the 2.13 mm i.d. horizontal smooth circular minichannel. Experimental data obtained cover comprehensive span of two-phase flow conditions such that total mass flux is in the range of 178 kg/(m2·s) ≤ G ≤ 885 kg/(m2·s), steam quality varies within 0.003 ≤ x ≤ 0.118 and saturation temperature is ranging between 120.2 °C ≤ Ts ≤ 151.8 °C. The flow patterns were observed visually and images of interest were recorded and subsequently identified based on a map from the literature. There are three basic two-phase flow patterns studied such as slug, slug-annular and churn occurring in the tested minichannel during intermittent flow. Measurements of the local peripherally averaged condensation heat transfer coefficient for each of the patterns considered were carried out using of a heat flux sensor.Based entirely on empirical results achieved the correlation equations specific to the patterns studied have been developed in terms of pertinent dimensionless numbers predicting values of the condensation heat transfer coefficient measured at deviation of ±15%. The correlations show that the condensation process studied combines contributions by gravity induced falling-film condensation with superimposed influence of the liquid phase axial flow, steam quality and interactions by capillarity and surface tension forces.Validity of the correlations proposed is presented in terms of variability ranges of the dimensionless numbers employed specific for each of the pattern studied such as slug, slug-annular and churn. The data predicted on the correlations developed are then compared against those computed on well recognized contributed relationships referenced to steam in flow condensation found in the literature and discrepancies between the predicted and contributed results are displayed and discussed. The comparison reveals some cases for which the results predicted on the correlations proposed can differ substantially from those computed on existing contributions particularly when referenced to intermittent flows at slug and churn patterns.

Improved correlation for predicting heat transfer coefficients during condensation inside smooth horizontal tubes

Abstract This study presents an improved correlation for predicting heat transfer coefficients for condensation inside smooth macro-tubes. Experimental data was obtained for various fluids, including R12, R1234yf, R1234ze, R134a, R22, R263fa, R245a, R32, R404a, R410a, and R600a. Tube diameters ranging from 3 to 14 mm, mass fluxes ranging from 50 to 1400 kg/m2s, and a vapor quality between 0 and 1 were used to cover a wide range of operating conditions. This data included 1683 data points from 50 sources. The comparison of the existing experimental data base with different correlations showed that the Cavallini et al. correlation had a mean absolute deviation of 19%, followed by those made by the correlations of Koyama and Yonemoto (24%), Dobson and Chato (24%), Huang et al. (24%), Shah (29%), and Haraguchi et al. (33%). Based on this comparison, an improved correlation modelled after the correlation of Cavallini et al. correlation was proposed. The accuracy and reliability of the proposed correlations were evaluated by comparing the predicted values with independent experimental data from the literature, wherein it was found that this new correlation predicted the databank with a mean absolute error of 17%. It was also found that this new proposed correlation provided better predictions of the heat transfer coefficient than existing correlations. The proposed correlation will improve the design and optimization of heat exchangers used in various industries, as well as provide valuable insights into condensation behavior inside smooth macro-tubes.

Prediction of effective heat transfer coefficients for vapour condensation inside horizontal tubes in stratified phase flow

In modern condensers of air conditioning systems, heat pumps, evaporators of seawater desalination systems, and heaters of power plants, the process of vapour condensation is carried out mainly inside the horizontal tubes and channels. Heat transfer processes occurring in condensers have a significant effect on the overall energy efficiency of the mentioned systems. In this paper, the experimental investigation of heat transfer during condensation of freons R22, R406a, and R407c in the plain smooth tube with d = 17 mm were carried out with the following parameters: ts = 35–40°C, G = 10–100 kg/(m2s), x = 0.8–0.1, q = 5–50 kW/m2, ΔT = 4–14 K. The unique measurements of circumferential heat fluxes and heat transfer coefficients were carried out with the thick wall method during different condensation modes. It can be inferred that with the increase of the heat flux, at the top part of the tube the thickness of the condensate film increases, which leads to the decrease in heat transfer. At the bottom of the tube, the increase in the heat flux enhances heat transfer coefficient, that is characteristic of the turbulent liquid flow in the tube. The obtained results allowed improving the prediction of effective heat transfer coefficients for vapour condensation, which takes into account the influence of condensate flow in the lower part of the tube on the heat transfer. This method generalises with sufficient accuracy (error ± 30%) the experimental data on condensation of freons R22, R134a, R123, R125, R32, R410a, propane, isobutene, propylene, dimethyl ether, carbon dioxide, and methane under stratified flow conditions. Using this method for designing heat exchangers, which utilise such types of fluids, will increase the efficiency of thermal energy systems.