Average Condensation Heat Transfer Coefficient Research Articles

Comparative analysis of condensation heat transfer and pressure drop of low GWP near-Azeotropic mixture and R-290 in a plate heat exchanger

Downward condensation of a near-azeotropic low GWP refrigerant mixture of R290/R1270 (65%/35% wt.), named HC01, was investigated inside an offset strip-fin (OSF) flow-structured plate heat exchanger (PHE). This study tested the prototype heat exchanger with HC01 and compared the condensation heat transfer coefficient (CHTC) and pressure drop (CPD) with the pure R-290 for working conditions of refrigerant mass flux (G) = 20–50 kg/m2s, inlet vapor quality (xin) = 0.2–0.9, saturation temperature (Tsat) = 40–55 °C, and heat flux (q) = 4–13 kW/m2. It was observed that the condensation of HC01 occurred entirely within the forced convection condensation flow regime, despite a slight change in the CHTC at a lower xin as the G increased. The CHTC demonstrated an increase in response to higher values of G and q, but decreased with increasing Tsat. Similarly, the CPD exhibited an increase with higher G and a decrease with lower Tsat, whereas the q had minimal influence. Comparison results showed that the HC01 exhibited 14.2% higher average CHTC but 6.5% lower CPD than that of R-290 because of the differences in properties, such as liquid thermal conductivity, viscosity, surface tension, latent heat, and discrepancies in liquid and vapor phase densities. Correlations were generated to predict the values of the Nusselt number (Nu) and friction factor (FF) of HC01, with mean absolute errors of 12.1% and 12.7%, respectively.

NUMERICAL AND EXPERIMENTAL INVESTIGATIONOF STEAM FILM CONDENSATION ON A VERTICAL TUBE

NUMERICAL AND EXPERIMENTAL INVESTIGATIONOF STEAM FILM CONDENSATION ON A VERTICAL TUBE

The Effect of Heat Exchanger Tube Structure on the Condensation Heat Transfer of R1234ze(E)/R152a Inside Smooth Tubes

Abstract In this paper, the flow condensation heat transfer characteristics of the environmentally friendly nearly-azeotropic refrigerant R1234ze(E)/R152a (mass ratio of 40:60) in smooth tubes with varying structures were numerically investigated. Under the operating conditions of mass flux of 400 kg/m2/s, heat flux of 12 kW/m2, and saturation temperature of 308.15 K, this study investigated the influence of circular tube inner diameter, elliptical tube aspect ratio, and installation orientation on condensation heat transfer, while the influence on pressure drop has not been taken into account in the present study. The results indicate that the condensation heat transfer coefficient in the tube increases as the inner diameter of the circular tube decreases. The condensation heat transfer coefficient increases by 1.086 times when the circular tube inner diameter is reduced from 10.7 mm to 5 mm. Under identical operating conditions, the condensation heat transfer coefficient of the mixed refrigerant in elliptical tubes increases with an increase in the aspect ratio. The average condensation heat transfer coefficient increases by 18.21% as the aspect ratio of the elliptical tube increases from 1 to 2. Compared to a vertical elliptical tube, a horizontal elliptical tube is more favorable for condensation heat transfer within the tube.

Condensation heat transfer characteristics and generalized correlations of R404A, R448A, and R454C in a plate heat exchanger

Although numerous studies have been carried out on alternatives to R134a and R410A to cope with regulations, the heat transfer characteristics of refrigerants with a low-global warming potential to replace R404A in a plate heat exchanger (PHE) have not yet been intensively investigated. Generally, R448A has been considered as a short-term alternative to R404A, while R454C has been nominated as a long-term alternative to R404A. In this study, the thermal and hydrodynamic characteristics of R404A, R448A, and R454C in a PHE during condensation are experimentally investigated at vapor qualities (x) of 0.2–0.8, mass fluxes (G) of 15–35 kg m−2 s−1, heat fluxes (q”) of 3–7 kW m−2, and saturation temperatures (Tsat) of 20–27 °C. The results of the analysis show that the condensation heat transfer coefficient (HTC) and frictional pressure drop (FPD) are predominantly affected by the x and G, while the q” barely affects the FPD. The average condensation HTC and FPD of R448A and R454C exceed those of R404A by 17.25–20.57% and 9.6–10.72%, respectively. Additionally, new generalized correlations of the condensation Nusselt number and frictional pressure drop for R404A, R448A, and R454C in a PHE are developed with mean relative deviations of −1.905% and 1.01%, respectively.

Experimental study on heat transfer characteristics of steam underwater direct-contact condensation

Introduction: The direct-contact condensation (DCC) of steam under water injection is the basic thermodynamic process of the bubble deaerator. In order to understand the complex coupling behavior of strong turbulence and fast phase-change heat transfer involved in the process.Methods: This study uses a visualized method and convective heat transfer model.Results: Since the contact area is affected by steam injection flow and sub-cooled degree is affected simultaneously, the trend of the condensation heat-transfer coefficient depends on the degree of their respective effects under each condition, and the maximum variation of the coefficient exceeds 104 W/m2.°C. Moreover, they still effect the period of steam plume, and the maximum variation of the period was beyond 80 ms.Discussion: Calculated the average condensation heat transfer coefficient and then produces the variation law of heat transfer coefficient under various conditions in one steam plume evolution period.

Experimental comparison on condensation and evaporation outside double-side enhanced horizontal tubes

Experimental investigations of the condensation and evaporation of R410A on the outside of two double-side enhanced heat transfer tubes were conducted, and the tube performance was compared with that of a smooth copper tube. The research object consisted of a smooth tube with a length of 2000 mm and an outer diameter of 25.4 mm and two double-side enhanced tubes of the same size. The evaporation experiments were run under the following conditions: the evaporation saturation temperature was 7°C, water inlet temperature was 8°C–18°C, and water flow rate was 0.6–1.6 m3/h. The condensation experiments were run under the following conditions: the saturation temperature was 35°C, water inlet temperature was 21°C–30°C, and water flow rate was 0.4–1.6 m3/h. During the data processing, the heat transfer coefficient of the water side was obtained using the Gnielinski-Wilson method, and that of the refrigerant side was obtained using the thermal resistance separation method. The effect of the surface structure on the heat transfer performance was analyzed, and a strengthening measure was proposed. The experimental results indicate that the evaporation heat transfer coefficients outside the smooth tube increased with the raise of the inlet water temperature, while the double-side enhanced tubes decreased; both the condensation heat transfer coefficients outside the smooth tube and the enhanced tubes increased with the increase of the water flow rate. Due to the different type of enhanced tube ribs, tube #3 surface structure is more conducive to the formation of vaporization core, which is about 30% higher than the outer heat transfer coefficient of tube #2. It is more in line with the requirements of strengthening horizontal single tube external pool boiling heat transfer. In the condensation experiment, the condensation heat transfer coefficients outside the smooth tube increased with the raise of the inlet water temperature, while the double enhanced tubes decreased; both the condensation heat transfer coefficients outside the smooth tube and the enhanced tubes increased with the increase of the water flow rate. With the analysis of the rib structure, the outer surface structure of tube #2 has stronger drainage capacity, and the external average condensation heat transfer coefficient is about 7% higher than that of tube #3, which is more in line with the requirements of condensing heat transfer outside the single tube.

임계점 부근의 이산화탄소-메탄 혼합물의 관내 응축 열전달 특성 연구

The condensation heat transfer coefficient and pressure drop for pure CO₂ and CO₂+CH₄ mixture were investigated under the near-critical condition, which simulates the CO₂ transporting conditions under Carbon Capture and Storage (CCS) process. The experimental facility consisted of a test section, heat exchangers, mass flow meters, temperature sensors, a magnetic gear pump, and a differential pressure transducer. The test section made with a copper tube was assembled with Polyvinyl Chloride (PVC) pipe to form a double tube. The condensation temperature and mole fraction of CH₄ in the CO₂ mixture ranged from 20℃ to 30℃, and 1% to 5%, respectively. The mass flux was changed from 500, 600, and 700 kgm-2s-1. The two-phase flow pattern under the set conditions was estimated to be the annular flow. When the mole fraction of methane in the mixture increased from 1% to 5% at 20℃ of condensation temperature, the average condensation heat transfer coefficients and the pressure drop for CO₂+CH₄ decreased from 4.97% to 19.9%, and 30.0% to 54.5%, respectively, compared to those for pure CO₂

Experimental study on enhancement characteristics of steam/nitrogen condensation inside horizontal multi-start helical channels

Abstract The aim of this study was to reveal the internal mechanism of enhanced condensation heat transfer, by experimentally performing steam condensation with higher inlet velocity in the horizontal multi-start helical channels (HMSHCs), and investigating the influences of pressure of steam, mass flowrate of cooling water, and mass fraction of noncondensable (NC) gas on steam condensation performance. Taking steam condensation in horizontal circular condensation channel (HCCC) as a reference, the condensation heat transfer coefficients (CHTCs), the outlet condensate mass flowrates (CMFRs), and the total steam condensation pressure drops (SCPDs) were compared and discussed, respectively. The results indicated that NC gas had a strong inhibitory effect on steam condensation, and average condensation characteristics decreased with the increase in NC gas fraction for lower Rem. But for higher Rem, the gas–liquid interfacial shearing stress can likely weaken the negative effect of NC gas. In addition, increasing the cooling water flowrate can entirety promote steam condensation. The comparison results indicated that steam condensation performance of HMSHC is better than that of HCCC under same experimental conditions. For the specific experimental scope, the average CHTCs and the outlet CMFRs in HMSHC are approximately 2.35 and 1.25 times of that inside HCCC, respectively, while the overall SCPDs in HMSHC are about 1.16 times of that inside HCCC. After introducing the performance evaluation factor, the calculation results revealed that the performance evaluation factor h PEC {h}_{\text{PEC}} of the average CHTCs in HMSHC is approximately 2.02, and the performance evaluation factor m PEC {{m}}_{\text{PEC}} of the outlet CMFRs in HMSHC is approximately 1.08. The two evaluating values are reasonable.

A neural network model for free-falling condensation heat transfer in the presence of non-condensable gases

Condensation heat transfer has been widely studied for various applications such as power generation, water desalination, data centers, chemical and pharmaceutical syntheses, heating and air conditioning systems, and especially, the passive containment cooling system (PCCS) in nuclear power plants. The PCCS is designed to reduce the risk resulting from a loss of AC power or compounding human error. In a hypothetical accident situation, one of the main safety systems, the PCCS, condenses water vapor with gravity-driven force to remove the heat from the containment vessel. Although the condensation heat transfer in the presence of non-condensable gases for predicting the heat transfer performance of the PCCS has been successfully investigated, there is still no generalized model or correlation available. In this work, we focused on the development of universal models for predicting the heat transfer coefficients of free-fall condensation heat transfer on the external surfaces of vertical tubes in the presence of non-condensable gases. For this, we created a consolidated database covering a broad range of geometric values and operating conditions, including tube hydraulic diameter Dh = 10–41.2 mm, tube length L = 0.3–3.5 m, total pressure Ptot = 0.15–2.0 MPa, wall subcooling temperature ΔTsub = 5–71 K, average condensation heat transfer coefficients of 90 ≤ ͞h ≤ 19,400 W/m2K, and Reynolds numbers of the film of 8 ≤ Refilm ≤ 7160. We analyzed the influence of varying the geometric and operational parameter values by using this database. Conventional machine learning techniques such as nonlinear regression and multilayer perceptron (MLP) neural network methods were adopted to predict the condensation heat transfer rate based on the consolidated database. Moreover, the prediction accuracies of the condensation heat transfer rates of the proposed prediction models and 12 relevant correlations were compared by using the consolidated database. The proposed nonlinear regression model exhibited good prediction accuracy with a mean absolute error (MAE) of 12.7 % for average ͞h, which is much lower than those achieved by previously proposed relevant correlations. In addition, the MLP neural network model showed excellent prediction accuracy with an MAE of 4.2 % for the consolidated database.

Thermal-hydraulic test facility for nuclear reactor containment: Engineering design methodology and benchmarking

The paper describes detailed thermal and mechanical design procedure of a CONtrolled FLOw (CONFLO) facility and a complimentary Thermal HYdraulic test facility for CONtainment (THYCON), to investigate the post-severe accident scenarios in Nuclear Power Plant (NPP) containments, involving condensation of steam in the presence of non-condensable gases (NCGs), such as air and hydrogen/helium. The former setup allows the study of flow condensation of steam on flat surfaces kept inside a rectangular flow section of 250 mm × 200 mm, under different inlet conditions of mixture concentration, pressure and temperature. The latter is a large cylindrical chamber of total height = 3.6 m and diameter = 0.96 m (vessel volume of 2.7 m3), mimicking a containment, wherein steam condensation and mixing transport of non-condensable gases can be experimentally simulated, as per conditions close to accident scenarios. Parameters of interest are local and average condensation heat transfer coefficient, NCG concentrations, flow Reynolds number, volumetric Richardson number, operating gas/vapour pressure, temperature and inclination angle of condensing surfaces. After due benchmarking of both the setups, the generated experimental data is being used for developing the design equation(s) to model steam condensation in containment environments and for suggesting locations for condensers and passive autocatalytic recombiners essential for containment safety. Ongoing experiments are also providing data for the validation of computer codes. The thermal-hydraulic experiments suggest that the condensation heat transfer inside NPP containments is primarily governed by several interlinked phenomena, such as stratification, mixing, turbulence and condensation.

A Comparative Study on the Condensation Heat Transfer of R-513A as an Alternative to R-134a

This paper presents the two-phase condensation heat transfer and pressure drop characteristics of R-513A as an alternative refrigerant to R-134a in a 9.52-mm OD horizontal microfin copper tube. The test facility had a straight, horizontal test section with an active length of 2.0 m and was cooled by cold water circulated in a surrounding annular space. The annular-side heat transfer coefficients were obtained using the Wilson plot method. The average heat transfer coefficient and pressure drop data are presented at the condensation temperature of 35 °C in the range of 100–440 kg·m−2·s−1 mass flux. The test data of R-513A are compared with those of R-134a, R-1234yf, and R-1234ze(E). The average condensation heat transfer coefficients of the R-513A and R-1234ze(E) refrigerants were similar to R-134a at the lower mass flux (100~150 kg·m−2·s−1), while they were up to 10% higher than R-134a as the mass flux increased. The pressure drop of R-513A was similar to R-1234yf and 10% lower than that of R-134a at the higher mass flux. The R-1234ze(E) pressure drops were 20 % higher compared to those of R-134a at the higher mass flux.

Precise determination of inundation effect coefficient of film condensation on an array of horizontal new three-dimensional finned tube

To accurately evaluate the condensation heat transfer performance of new 3D finned tubes in shell-and-tube condenser, the inundation effect of the film condensation of R-134a on an array of 6 horizontal new 3D (three-dimensional) finned tubes is experimentally investigated with a new experiment method of homologous method. And the precise inundation effect coefficient of film condensation is determined. A novel test facility, whose test section contains two arrays of 8 horizontal tubes to realize the homologous method, is developed and constructed. The outer diameter of the tube and effective tube length in the test section are 19.05 and 500 mm, respectively. The condensation heat transfer coefficient of new 3D finned tube and inundation effect coefficient of new 3D finned tube bundle are determined under different conditions. The results show that the inundation effect coefficient of new 3D finned tube bundle decreases from 1.00 to 0.78 as Re increases from 75 to 1860. And the effect of heat flux on the inundation effect is more sensitive than the condensing temperature. Furthermore, for new 3D finned tube, the condensation heat transfer and inundation effect models are established, and the deviations of results between experiment and models are almost within ±6.0%. In comparison with literatures, the average inundation effect coefficient of new 3D finned tube bundle is 10.0-25.0% higher than that of 3D finned tube bundle in literatures, within 3.0% lower than that of two-dimensional finned tube bundle, and 15.2% higher than that of plain tube bundle. And the average condensation heat transfer coefficient of new 3D finned tube bundle in this article is 5.0-25.0% higher than that of 3D finned tube bundle in literatures, 10.0-30.0% higher than that of 2D finned tube bundle, and more than 10 times that of plain tube bundle. The precise inundation effect coefficients can be used as benchmark data to build precise and universal inundation effect model of 3D finned tube, and the models established in this study will help guide the thermal design of the new 3D finned tube applied in shell-and-tube condenser.

Experimental investigation on steam/nitrogen condensation characteristics inside horizontal enhanced condensation channels

Abstract In order to investigate heat transfer characteristics of steam/nitrogen condensation inside horizontal enhanced condensation channels (HECCs), experiments have been performed, respectively, inside HECC and horizontal circular channel (HCC). HECC is formed by inserting different reinforcers into HCC including horizontal multi-start straight channels (HMSSCs) and horizontal spiral channels (HSCs). Effects of nitrogen mass fractions on average condensation heat transfer coefficients (CHTCs), average outlet condensate mass flowrates (CMFRs), and average steam-side pressure drops (SSPDs) are analyzed, respectively. The results indicate that HECC has better condensation performance than HCC under the same conditions, while average SSPDs of HECC will increase slightly. Then, HMSSC is compared against HCC, and enhancement factors of average CHTCs and average outlet CMFRs are about 1.45 and 1.12, respectively, while the enlargement factor of average SSPDs is about 1.16. Similarly, HSC is compared against HCC, and enhancement factors of average CHTCs and average outlet CMFRs are about 1.25 and 1.05, respectively, while the enlargement factor of average SSPDs is about 1.12.

Numerical Simulation of Condensation Heat Transfer and Structural Optimization in Dryer of Paper Machine

In order to improve the heat transfer efficiency of the multi-channel dryer, based on the Navier-Stokes equations and the standard two equation kinetic-ε (epsilon) turbulent model, the Volume of Fluid model in fluent software was used to simulate the two-phase flow field of the condensation heat transfer in a micro-channel of dryer, the structural optimization and the influence of process parameters on the uniformity of temperature distribution were analyzed. The results showed that the saturated water vapor began to condense and release heat when it entered the channel, and with the flow of water vapor in the channel, the channel surface presented a certain range of temperature distribution, the condensate converged at the bottom of the channel and the liquid film gradually thickened along the channel. In general, the heat transfer coefficient of the multichannel dryer is high, and the temperature difference between the inlet and outlet of the channel can be reduced by the reverse convection heat transfer in the multi-channel dryer with double inlet, the relationship between the speed of dryer and the average condensation heat transfer coefficient shows an increasing trend of slope decreasing.

Experimental study on film condensation heat transfer characteristics of R134a, R1234ze(E) and R1233zd(E) over condensation tube with enhanced surfaces

This paper presents an experimental study on the film condensation heat transfer characteristics of a horizontal smooth tube and an enhanced tube using R134a, R1233zd(E) and R1234ze(E). The objectives of this paper are to develop experimental correlations of heat transfer for enhanced tubes used in a film type condenser and to provide a guideline for design of the film type condenser. Tests are performed on a horizontally smooth tube with a 19.05 mm diameter and three enhanced tubes. The temperature of the saturated vapor inside the condenser is 38 °C. In the case of the horizontal smooth tube, the film condensation heat transfer coefficients of R1234ze(E) and R1233zd(E) were approximately 10.97% and 10.04% lower than those of R134a, respectively. The experimental values obtained from the horizontal smooth tube agreed well with the theoretical value of Nusselt’s film which were within the ±10% error range. In the enhanced tubes experiment, the film condensation heat transfer characteristics according to the number of knurling and Fin per inch were examined. The enhanced tubes E.T(C)-1 and E.T(C)-3 exhibit a fin per inch number value of 55 and 85 and 107, respectively. Moreover, the fin per inch and knurling number of E.T(C)-5 are 60 and 117, respectively. As a result, the film condensation heat transfer coefficient was found to decrease with increasing heat flux, and E.T (C) -5 showed the highest average film condensation heat transfer coefficient for all refrigerants. Based on the experimental results, the effect of the fin per inch number on the heat transfer coefficient outside the tube is greater than that of the knurling number. In this study, the equations for film condensation heat transfer coefficient for each refrigerant and each enhanced were derived tube according to the heat flux, and a total of nine correlations were observed to have an accuracy of ±10% within the experimental range.

Mechanism of Condensation Enhancement by Corrugated Low Finned Tubes in Presence of Noncondensable Gas

Corrugated tubes are the most convenient reinforcement techniques to enhance intube condensation. In this paper, the average condensation heat transfer coefficients inside the corrugated low finned tube and smooth tube were firstly introduced. The distribution of local heat transfer coefficient was presented at lower and higher inlet noncondensable gas mass fractions. The results show that the major heat transfer resistance is the thermal resistance of liquid film at lower inlet gas fraction. So the mechanism of condensation enhancement by corrugated low finned tubes is the increase of liquid film condensation coefficient. But at higher inlet gas fraction gas layer mass transfer resistance becomes the control thermal resistance. The spiral ribs inside corrugated low finned tube can thinner not only the gas layer thickness but also the liquid film thickness. The mechanism of condensation enhancement is the increase of both gas layer and liquid film condensation coefficient.

Obtaining a model for the determination of the average condensation heat transfer coefficient in ACC systems

This work presents the results of the continuity of the research process carried out in the Energy Studies Center belonging to the Faculty of Technical Sciences of the University of Matanzas, which involves the establishment of a dimensionless model to determine the average condensation heat transfer coefficient of Air Coleed Condenser (ACC) systems in straight and inclined tubes. The research consists in obtaining in an analytical way the solution of the differential equation of the velocity profile, considering that condensation is of pellicular type, finally the empirical condition of Roshenow is combined with the theoretical solution to generate a numerical expression that allows obtaining with a 15.2% of deviation in 2,192 tests, a value of the average coefficient of heat transfer by condensation very similar to the one obtained with the use of the most referenced model in the consulted literature, the empirical model of Chato.

Comparative study of heat transfer enhancement on liquid-vapor separation plate condenser

AbstractBasic structures of liquid-vapor separation cooling plates (LSCPs) and a liquid-vapor separation plate condenser (LVSPC) are innovatively designed. Strengthening heat transfer principle of the LSCPs is demonstrated by theoretical analysis. The average condensation heat transfer coefficients (ACHTCs) of the LSCPs are calculated and compared with conventional cooling plate (CCP). Results show that for a laminar flow, the ACHTCs of 2-parts liquid-vapor separation cooling plate and 3-parts liquid-vapor separation cooling plate are respectively 19% and 32% higher than the ACHTCs of the CCP in the same conditions. The ACHTC ratio of N-parts liquid-vapor separation cooling plates (NLSCP) to CCP is $\sqrt[4]{N}$in the same conditions. For a turbulent flow, results show the smaller the height of condensation area, the greater the ACHTCs of cooling plate. In the LVSPC study, operation conditions include the refrigerant R134a mass flux ranging from 22 to 32 kg/(m2.s) and inlet vapor quality from 0.5 to 1 for the saturated temperature of 40∘C. Calculation results showed that the ACHTCs of the LVSPC are 6–24% higher than the ACHTCs of the given common plate condenser (CPC), and similar to the CPC, the ACHTCs of the LVSPC increases with the increase of mass flux and vapor quality.

Theoretical Modeling of Vapor Condensation in the Presence of Noncondensable Gas on a Horizontal Tube

Abstract Double-boundary layer theory was adopted to investigate the distributions of the liquid film, gas film, heat transfer coefficient, and condensate mass fluxes around a horizontal tube for vapor condensation with noncondensable gases like steam–air and steam–CO2 mixtures under free convection. The investigation considered the effects of the noncondensable gas concentration, surface subcooling temperature, and pressure. The thicknesses of the liquid and gas films increase gradually along the wall from top to bottom, whereas the local heat transfer coefficient and the condensate mass flux decrease. The film thicknesses do not change significantly around the upper part of the tube but increase sharply around the lower part. The liquid film thicknesses, gas film thicknesses, condensate mass fluxes, and heat transfer coefficients of steam–air systems are compared with those of steam–CO2 systems. The condensate mass flux in the steam–air system is smaller than that of steam–CO2 system under the condition of the same surface subcooling and gas mass fraction because air has more moles of molecules in the mixture than CO2 and the steam more easily diffuses through CO2 than through air. The predicted average condensation heat transfer coefficients agree well with the available experimental data.

Experimental study on condensation heat transfer of FC-72 in a narrow rectangular channel with ellipse-shape pin fins: Ground and microgravity experiments

A new type of three-dimensional pin–fin plate with elliptical cross-section was proposed. Condensation heat transfer of FC-72 in a narrow rectangular channel with the proposed pin fins was experimentally studied in normal gravity and microgravity. The effects of pin geometry, thermal conductivity, mass flow rate and gravity on condensation heat transfer were investigated. The visualization experiment under microgravity was carried out and the condensate behaviour was observed by high CCD camera. The results showed that all the elliptical pin-fin plates exhibited substantially better performance than the flat plate. The influence of pin geometry and thermal conductivity on condensation heat transfer coefficient was great. The smaller pin size and higher thermal conductivity were favourable for condensation enhancement. The average condensation heat transfer coefficient increased with the increase of mass flow rate. In microgravity, obvious fluctuations and climbs occurred in gas-liquid interface. However, the condensate behaviour on the condensing surface was unconspicuous. For unsteady state, the vapor-side temperature difference increased evidently in microgravity. Microgravity had a certain effect on temperature evolution of the condensing base. Short-term microgravity degraded the condensation heat transfer coefficient in quasi-steady state or unsteady state, but had little effect on pulsating state.