Condenser Tubes Research Articles

Chaotic quasi-oppositional arithmetic optimization algorithm for thermo-economic design of a shell and tube condenser running with different refrigerant mixture pairs

Chaotic quasi-oppositional arithmetic optimization algorithm for thermo-economic design of a shell and tube condenser running with different refrigerant mixture pairs

Measurements of the liquid film thickness for annular flow during flow condensation in a circular tube

Liquid film thicknesses of R245fa and zeotropic mixtures of R134a/R245fa were measured during flow condensation in circular micro-channel using a CCD camera and a Laser Focus Displacement Meter (LFDM). The fluctuation characteristics were studied along with the average liquid film thickness and the thermal resistance. The average liquid film thickness had no obvious association with the temperature glide. The liquid film fluctuation frequency was most strongly affected by the vapor-liquid interface shear force with the liquid film thickness determining the fluctuation range. Larger mass fluxes weakened the thinning effect of the mass flux. With increasing R134a mass fraction, the impact of mass flux was much obvious. With increasing R134a mass fraction, the liquid film thermal resistance increased. The laminar liquid film momentum equation was used to develop a simple method to predict the mean liquid film thickness.

Active Cooling System for Downhole Electronics in High-Temperature Environments

Abstract Downhole high-temperature environment is an important factor affecting the performance of downhole electronic system. At present, various active cooling technologies and passive cooling technologies have been proposed to reduce the temperature of downhole electric circuit system. However, passive cooling technologies can only provide limited cooling capacity for drilling tools under high-temperature environment, and the duration of cooling is short, which cannot meet the long-time drilling task. This paper presents an active cooling system (ACS) for downhole electronics and the effects of different temperatures on the performance of electronic components are analyzed. The ACS mainly includes a micro supercharger, condenser tube, evaporation pipe, capillary tube, and refrigerant. The theoretical analysis of heat transfer and refrigerant capacity in high-temperature environment is carried out. The thermal characteristics of the ACS are evaluated experimentally. The results show that the temperature of electronic components can be reduced to below 163 °C in the 200 °C downhole environment and components. The geomagnetic field data measured by electronic components at room temperature, 200 °C and with ACS are compared. The results show that ACS can keep electronic components working normally.

Excitation of pipe bending modes by internal pressure: A phenomenon present in refrigerators with skin condenser

The concept of skin condenser refrigerators has been increasingly explored for its capacity to provide a larger internal cabinet volume. However, the discharge pulsation of the cooling gas has become a significant source of noise because it directly excites the cabinet. This paper analyzes the mechanisms of cabinet vibration excitation by gas pulsation in the condenser tubes. Initial tests were performed with vibration measurements on a refrigerator and on segments of the cabinet excited by pulsation only. The results showed that bending modes of cabinet segments were excited by the pulsation in the condenser tube. A theoretical analysis showed that asymmetry in the condenser tube cross section is responsible for bending moment generation and numerical evaluations confirmed this effect for different types of asymmetries.

Numerical Study the Effect of Gap Ratio on Flow Characteristics and Heat Transfer in Staggered Tube Banks

Condenser is a type of heat exchanger that serves as condensation for turbine output steam. In general, a steam power plant uses a surface condenser. This type of condenser is a type of shell and tube. Condensers have a phenomenon of convection heat transfer. The change in distance between condenser tubes is one way to increase the rate of heat transfer. To produce maximum heat transfer, it can be determined by the variety of distances between tubes. The research was conducted by analyzing the flow characteristic and heat transfer around condenser tube banks with gap ratio variation (s/d), which compares transverse distance (ST ) and tube diameter (d) with variations of 3.2, 2.7, 2, and 1.7. 2-dimensional simulation with Computational Fluid Dynamics (CFD) is a numerical method and algorithm for solving and analyzing problems that occur in fluid flows. Based on the results obtained, the smaller the Gap Ratio, the lower the outlet temperature produced and the maximum heat transfer, but the pressure drop value obtained the bigger. Also, the smaller Gap ratio, the bigger v max produced. The lowest outlet temperature value at the variation of 1.7 is 310.66 K, and the coefficient of heat transfer is 103.34 W/m2K. Pressure drop produced at variation 1.7 is 515.99 Pa. Variation 2 is the best gap ratio variation, seen from the heat transfer result and the pressure drop value is not too large. The coefficient heat transfer and pressure drop in variation 2 are 76.95 W/m2K and 119.17 Pa.

Condensation Heat Transfer Performance of Vertical Condenser Tube with Slippery Liquid Infused Surface Coatings

Condensation Heat Transfer Performance of Vertical Condenser Tube with Slippery Liquid Infused Surface Coatings

Degradation of condensation heat transfer on a vertical cylinder by a light noncondensable gas mixed with air-steam mixtures

In this study, the experimental investigation result of steam condensation on a vertical tube in the presence of air and a light noncondensable gas is presented. This study aims at elucidating the effect of hydrogen that may be generated during the progression of a severe accident on the condensation heat transfer. Using helium as a simulant of hydrogen, a series of condensation tests were performed. A novel helium measurement system was introduced to analyze the composition of mixture gas. The condensation heat transfer coefficient was obtained under natural convection conditions on a 1 m long condenser tube having an outer diameter of 21.5 mm. A comprehensive experimental database was obtained to understand the parametric effect of the total mass fraction of noncondensable gases, molar concentration of helium in noncondensable gases, and wall subcooling degree. An empirical correlation for the degradation factor to account for the effect of a light noncondensable gas was proposed for application to the condensation model for the steam–air mixture based on the experimental data. The strategy to adopt the degradation factor was assessed against three steam–air–helium condensation tests.

Effect of Tube Expansion on Heat Transfer and Pressure Drop Characteristics During Condensation in Micro-Fin Tubes

Despite of the large number of research dedicated to condensation heat transfer and pressure drop characteristics in pristine micro-fin tubes, experimental investigation on effects of tube expansion have not been reported in the open literature. The paper reports measured cross-sectional dimensions, condensation heat transfer and pressure drop data of R1234ze(E) in pristine (5.10 mm OD) and expanded (5.26 mm OD) micro-fin tubes with mass fluxes from 100 to 300 kg/(m2·s). Effects of mass flux, vapor quality and tube expansion on the heat transfer coefficients and friction pressure gradients were investigated in the study. When the mass flux is 100 kg/(m2·s), the heat transfer coefficient and pressure drop of R1234ze(E) decrease after tube expansion. However, when the mass fluxes are 200 and 300 kg/(m2·s), tube expansion effects on the heat transfer coefficient and pressure drop are not notable. In addition, the experimental results are analyzed based on the existing condensation heat transfer and pressure drop correlations.

Experimental Analysis of the Vapour Compression Refrigeration System with Microchannel Condenser using R134a and R1234yf Refrigerant

Vapour Compression Refrigeration (VCR) system with high COP, low input power consumption and minimal exergy losses are of great research hotspot. The current research focuses on analysis of exergy and performance of vapour compression refrigeration (VCR) cycle is in a real-world application. Experiments were carried out in the VCR system using round tube condenser and microchannel condenser along with different refrigerants R134a, and R1234yf. Temperatures were varied from +20°C to 5°C for the evaporator and 40°C to 50°C for the condenser. Among the two refrigerants, experimental results show that refrigerants operating in micro-channel condensers have COP of 6% and 4%greater higher with5% and 3% lower exergy loss compared to the round tube condenser for R134a and R1234yf respectively.R1234yf appears to be a better equivalent for R134a, according to the findings. The efficiency defect in the condenser is the greatest and least in the evaporator for the coolants examined.

A case study on experimental and statistical analysis of energy consumption of domestic refrigerator

This paper presents the energy consumption analysis of the refrigerator and the effect of the condenser on it. According to the Bureau of Energy Efficiency (BEE), India, the energy efficiency of electric appliances is the key parameter for testing their performance before domestic use. For energy consumption analyses, the experimentation was conducted on the domestic refrigerator (165 L) top-mounted evaporator by retrofitting the refrigerator with an Elliptical Helical Coil Condenser (EHCC) and existing refrigerator with a Straight Tube Condenser (STC). Box-Behnken Design (BBD) is very significant in determining the significant factor and reducing the number of experiments. BBD has been performed to analyze the significance of factors ambient temperature, fresh food compartment temperature and the heat load in energy consumption, and the Coefficient of Performance (COP) of a refrigerator. The heat load and the ambient temperature are both very significant in determining the refrigerator's energy consumption. The most important thing is to increase the liquid content in the charge before it is supplied to the evaporator to extract more amount of heat to increase the cooling effect. The ANOVA (Analysis of Variance) results show that the ambient temperature and the heat load were more significant in increasing energy consumption and decreasing the COP and vice versa. The results of ANOVA and the experiment are very close; the R2 value 0.995 precisely matches the R2 adj. value 0.994. The statistical analysis using the Box-Behnken design produces a good fitting of the modeled and experimental data set. The present study aims to examine the effects of said factors and the condenser on the domestic refrigerator's energy consumption and COP. The study exhibits some enhancement in the COP to 2.59 contrary to 2.45 and energy consumption reduced to 1191 Wh from 1755 Wh during the trial of 24 h.

Experimental study of condenser material in the air conditioning system

In the air conditioning machine, condenser is considered to be the important component. The present study illustrates the condenser’s performance with relevant experiments. The role of a condenser is to release the observed heat from the cooling system because the energy is removed out and the condensed air get drained out and proceeds with its path through the presence of the expansion valve. This present study literally focuses on the external fins and the condenser tubes through the heat transfer mode by the process of forced convection. The temperature changes were calculated for both air temperature system and refrigerator system and appropriate analysis was performed for evaluating the performance of the condenser. The dimensions of the fins, shape and tubing arrangements are also analyzed. The principle of a condenser is to expel the heat out of the refrigeration system by the condensation of vapor. Generally, there is no phase change occurring in the external fluids. In the condenser operated with forced convection mode, the circulated air over the specific surface is maintained with the help of a blower for effective heat transfer. The heat rejection from the condenser is theoretically calculated from the standard value of the compression cycles, without the considering the addition of heat supplied by the compressor inefficiency. The fluid flow of the refrigerant is assisted by the external gravity and hence the inlet tube is aligned at the top whereas the outlet tube is aligned at the bottom. The concept of pipe rising is excluded from the design and extensive care is taken for the adjustment of pipe levels during installation process. Horizontal or vertical air flow is commonly preferred. In the attempt of comparison with various tubes of different diameters, it is considered to focus on smaller tubes with varying diameters to match with the internal surface area of a larger segmental tube.

Terlambatnya Proses Pendinginan Muatan Gas Polymer Grade Propylene di Kapal LPG/C Coral Millepora

The LPG Carrier is one of the ships that carries liquid gas cargoes below -48o C. The LPG Carrier has facilities in the form of a reliquefaction plant that uses seawater as a coolant for gas cargo. Therefore, the reliquefaction plant has an important role in the smooth loading and unloading process. If one of the reliquefaction plant particles is damaged, of course the cooling process of the polymer grade propylene gas load will be hampered. The purpose of this study is to describe the problem in the cooling process of polymer grade propylene load. The authors conducted research using a qualitative descriptive method through an interview approach, direct observation of the object of research, and supported by paper-based documents or photos. Based on the results of the study, it was found that the causes of delays in the cooling process of polymer grade propylene gas cargo, namely the influence of weather, sea water content, clogged sea water filters, clogged condenser tubes, and condenser shell tube leaks.

Dynamic characteristics of a domestic freezer with a microchannel flat-tube condenser

In this study, a microchannel flat-tube condenser was introduced to a domestic freezer, and experiments were conducted to investigate the dynamic characteristics of the system at different ambient temperatures. Based on the dynamic variations of temperature in the main components, the refrigerant migration during the compressor-off stage and cooling output performance during the compressor-on stage were analyzed. The results show that the time proportion of the no-cooling output stage increased from 4.9% to 7.3%, while that of the refrigerant migration decreased from 25.6% to 21.2%, and energy consumption for no-cooling output stage increases from 0.0016 kW·h to 0.0023 kW·h as the ambient temperature increased from 16 °C to 32 °C. In addition, the freezer was compared to a system with a traditional circular tube condenser. The results show that the microchannel heat exchangers could contain more refrigerant charge due to the multi-channel structure during the compressor-off stage, weakening the “evaporative cooling” effect and reducing the migration loss. Therefore, the microchannel flat-tube condenser exhibited better stability at different ambient temperatures. The results of this study elucidate dynamic characteristics and advantages of applying a microchannel flat-tube condenser to a freezer, and provide a direction for reducing the energy consumption of a domestic freezer.

Improving the Heat Transfer Rate of Air Conditioning Condenser by Material Optimization

Air conditioning systems have condensers that remove unwanted heat from the refrigerant and transfer the heat outdoors. The optimization of the global exploit of heat exchanging devices is still a burdensome task due to different design parameters involved. There is need for more and substantial research into bettering cooling channel materials so as to ensure elevated performance, better efficiency, greater accuracy, long lasting and low cost heat exchanging. The aim of this research work is to improve the heat transfer rate of air conditioning condenser by optimizing materials for different tube diameters. Simulations using thermal analysis and Computational Fluid Dynamic (CFD) analysis were carried out to determine the better material and fluid respectively. The analysis was done using Analysis System software. Different parameters were calculated from the results obtained and graphs are plotted between various parameters such as heat flux, static pressure, velocity, mass flow rate and total heat transfer. The materials used for CFD analysis are R12 and R22, and for thermal analysis are copper and aluminium. From the CFD analysis, the result shows that R22 has more static pressure, velocity, mass flow rate and total heat transfer than R12 at condenser tube diameter 6 mm. In thermal investigation, the heat flux is more for copper material at condenser tube diameter 6 mm. Copper offers maximum heat flux. Also, refrigerant R22 scores maximum for the heat transfer criteria, but cannot be recommended due to toxicity

Performance analysis and efficiency enhancement of cooling tower in 210 MW thermal unit

Heat exchangers, condensers plays a vital role in any kind of power cycle like modified Rankin cycle, these components involves transfer of both sensible and latent heat and have great influence over the power plant performance. The condenser employed in MTPS involves transfer of latent heat into steam. Yet it as to induce a phase change in thereby forming water. Increase in the effectiveness of condenser resulted in the increase of vacuum in the condenser. Thereby work done by steam is increased and coal saving (per ton of steam production) is achieved. This condensation process results in the formation of sludge’s (temporary) and (permanent). Along the inner periphery of the condenser tubes. These permanent scales have decreased thermal conductivity and inhibit the heat transfer rate. The more the thickness of the scale the less the heat is removed from the steam. This scale formation limits the life of the condenser tubes with maximum performance. In this project the thickness of the scale formed in the condenser tubes is calculated theoretically and the performance is analysed before and after scale formation in the condenser. Different materials which involve less scale formation, different ways of reducing scales and various scale removing methods are suggested.

Water recovery from wet flue gas by combining the amplification tube condensation and inlet particle-sorting cyclone separation

• A novel technical route was used to recovery of water from flue gas. • The amplification tube and separators were designed to enhance mass transfer process. • The amplification tube and separators have relatively economic performances. The wet flue gas which is generated after the Wet flue gas desulfurization process contains huge amount of water vapor, soluble salts and insoluble particles. Direct discharging will not only lead to the significant waste of water resources, but also causes continuous smog. Therefore, a series of amplification tube with different sizes (length of 40 mm, 80 mm, 120 mm, 160 mm and 200 mm) were designed to condense water vapor by changing the partial pressure. Meanwhile, a particle storing classifier combining with cyclone was used for improving the collection efficiency of condensed water. The result showed that the water collection efficiency raised first with increasing the length of amplification tube and dropped after it reached to the maximum point (11.2%) at the length of 120 mm with the pressure drop lower than 72.5 Pa. Furthermore, after classifier and cyclone separator were incorporated with the optimized amplification tube, the highest water collection efficiency increased by 9.4%, reaching about 19.4% which is equivalent to reducing the flue gas temperature by 4 °C by conventional heat exchange technique. This novel technology was successfully applied to recover water and deep purify wet flue gas for the first time and has great potential in industrial wet flue gas pollution control.

Experimental investigation of solar energy-based water distillation using inclined metal tubes as collector and condenser

ABSTRACT The solar still utilizes solar energy to produce potable water from brackish water, which may support agricultural and industrial sectors as well as the life of humans and animals. A conventional solar still normally distills an average freshwater of 2 L/m2/day which is not sufficient to meet individual daily demand. As a motivation for productivity enhancement, a new model of solar water distiller has been experimented with under Thailand climatic conditions. Its structure is not like a typical solar still, the low-temperature brackish water was supplied from the water tank to the condenser tubes for condensation rate improvement. After making a turn, the brackish water was heated up in blackened receiver tubes by absorbing solar radiation, which leads to a temperature growth of the feed water. The high temperature of outlet water in the receiver tubes plays a role as an additional heat for brackish water in the basin, which will enhance the temperature of basin water along with the evaporation rate. Various water feed rates and a variety of water depths were studied for their effect on the performance of the proposed solar still. The experimental conditions consisted of 0.5 cm, 1 cm, and 2 cm of water levels and 0.5 L/h and 1 L/h of mass flow rates. As the water level decreased from 2 cm to 0.5 cm, the daily productivity was improved by 34%. Additionally, there is a 28% growth in output as the mass flow rate of feed water declined from 1 L/h to 0.5 L/h. Further remarkably, in comparison with a conventional solar still under the same level of water depth, the daily distillate yield of the proposed model improved double and 58.5% at a water depth of 0.5 cm and 1 cm, respectively.

Transient Thermal Stress Calculation of a Shell and Tube Condenser with Fixed Tubesheet

AbstractThe present article deals with transient thermal stress calculation on a safety horizontal shell and tube condenser. This condenser is used in a power plant for cooling of hot steam diverted from the turbine in the case of its emergency shutdown. The standard stress calculation was provided according to the EN 13445 standard in steady regime. As consistent with this calculation, an expansion joint must be used on the shell. The main aim of this article is to describe a detailed calculation of the transient temperature field on the shell and tubes, using finite element method analysis, and longitudinal thermal stresses on the shell and tubes during the start‐up process. Transient analyses are useable for more accurate EN 13445 calculation and, furthermore, for fatigue calculation.

A generalized prediction model of waterside fouling for internally enhanced tubes in shell and tube condensers

• The applicability of the constant fouling resistance (factor) is verified. • The valid concentration is proposed to improve the accuracy of fouling model. • The effect of velocity on the deposit bond strength is studied experimentally. • The correlations for sticking probability and deposit bond strength are developed. • Two fouling prediction models are developed and verified. Fouling is one of the most significant problems for internally enhanced tubes installed in the shell and tube condensers. Due to the lack of long-term test data, current fouling models are developed based on accelerated particulate fouling tests that have the low precision and hence are inapplicable for predicting combined fouling in most practical cooling tower systems. In addition, the constant values of fouling resistance (factor) recommended by the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) are extremely limited under different operating conditions. To overcome these challenges, this research developed and validated two fouling prediction models based on experimental long-term tests. One of the models was in the form of a ratio of asymptotic fouling resistance of the enhanced tube to that of the plain tube ( R f ∗ / R f , p ∗ ), and the other one was in the form of the asymptotic fouling resistance of the directly enhanced tube ( R f ∗ ). Both models considered water quality, water velocity, and the tube geometries as the variables with the acceptable accuracy for prediction. 1) For the water quality, the parameter of valid concentration ( C com ) of cooling water was defined in this study, which reflected the potential amount of valid components to form the fouling. 2) For the water velocity, its impacts on the two critical parameters of the fouling process: sticking probability ( P ) and deposit bond strength ( ξ ) were investigated using experimental studies. Test results showed that in enhanced tubes with the increased water velocity the sticking probability ( P ) decreased continuously while the deposit bond strength (ξ) initially increased, and then, decreased. 3) For the tube geometries, by taking the parameters of tube geometries as variables the multi-variable correlations of the sticking probability ( P ) and deposit bond strength ( ξ ) were developed. From the results the generalized fouling prediction model as a ratio of asymptotic fouling resistance ( R f ∗ / R f , p ∗ ) was recommended for the application in HVAC&R industry due to its suitability and accuracy in practical project applications.

Sensitivity of the Non-Equilibrium Approach for Mixture Condensation to Heat and Mass Transfer Correlations and Thermophysical Properties

Abstract The prediction of mixture condensation is still complex due to the coupled heat and mass transfer and insufficient data of thermophysical mixture properties. This article analyzes the impact of various heat and mass transfer correlations on the non-equilibrium approach for mixture condensation in a vertical plain tube. Furthermore, the influence of thermophysical properties from different databases is investigated. The results are shown for ethanol-water, but allow conclusions to other fluid mixtures. They indicate that the liquid heat transfer coefficient in the non-equilibrium approach dominates the qualitative behavior of the condensation process, but the vapor mass transfer coefficient can only decrease or increase the quantitative level of the effective heat transfer with minor impact. More importantly, the logarithm in the vapor mass transfer term is central for the prediction of the condensation heat transfer. As this logarithm contains vapor-liquid equilibrium (VLE) data, it proves that there is a strong connection between VLE and overall prediction of mixture condensation. A demonstration of available data for thermophysical mixture properties of ethanol-water shows significant deviations, which affect the calculations as well. Besides, data from our own experiments are presented for mixture viscosity of ethanol-water. It is recommended to focus not only on improved heat and mass transfer correlations but also on thermophysical properties and VLE data for a precise prediction of mixture condensation.