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Loop Heat Pipes (LHPs) are highly efficient two-phase heat transfer cooling system devices extensively utilized in spacecraft. They operate passively and emerged as a significant advancement in spacecraft temperature control technology. It is mainly composed of evaporator, condenser, liquid, and vapor lines. The evaporator where the heat is applied employs a unique sponge-like material called a wick. The liquid from the wick is converted into vapor after absorbing the heat. This vapor is now transferred through the vapor line to the condenser, where the heat is released as it passes through sleek pipes and vapor is converted into liquid. The liquid again reaches the evaporator through liquid line and the cycle is repeated. The working fluid flow takes place with capillary action of wick. This article reviews the basic arrangement, development, and modelling details of LHP. [ABSTRACT FROM AUTHOR]

This paper deals with the improving performance of air conditioning system by reducing the compressor work. The copper tube with the cold-water supply reduces the temperature of the compressor and water is sprayed on the condenser coil. This reduces the temperature of condenser coil because specific heat capacity of water is 4.187kJ/kg, it is higher than that of air (0.718kJ/kg). Therefore, heat rejection can be carried out by both air and water. Spraying the water on the condenser coil also helps in cleaning its surface from the dust. When the temperature of condensing coil is reduced the work done by the compressor is also reduced. This reduction of heat is achieved by circulating the condensed water from the indoor system of an air conditioner. The waste water from the evaporator is used to cool the condenser; due to this additional cost for coolant is eliminated. The condensed water will have the temperature below the room temperature. So, the heat rejection can take place at faster rate. The compressor is prevented from overheating and other failure due to heat. There is continuous generation of water from the indoor unit, hence the cooling happened continuously. [ABSTRACT FROM AUTHOR]

This study presents a performance analysis of a Concentrating Solar Power (CSP) plant coupled to a Multi-Effect Distillation (MED) unit with an Air-Cooled Condenser (ACC) as the MED last condenser (configuration named as MED- ACC) to evaluate the advantage of this integration in comparison to the typical once-through condenser (configuration named as MED-OTC). The analysis has been performed for Crucero, Chile, which is located 100 km far from the coast and 1000 m above sea level. Thus, a seawater pumping system and energy recovery of the brine disposal are considered. The design of the MED-ACC plant has been carried out in terms of the ACC temperature limitations, and the simulation of both configurations has been performed on an hourly basis. Results obtained in the design show that configuration MED- ACC requires a lower number of effects than the MED-OTC configuration, which reduces the capacity and efficiency of the MED plant. A significant advantage of the former configuration is the reduction in the MED electric consumption with respect that of the latter configuration. Regarding annual performance results, it was found that the net electric output of the MED-ACC plant was 14% higher than the MED-OTC plant due to the seawater pumping consumption reduction, while the water production was 43% lower, despite the water capacity factor of both configurations remained similar. [ABSTRACT FROM AUTHOR]

The WASCOP (Water Saving for Concentrated Solar Power) project is an EU project dedicated to water saving in CSP power plants. Among the different technologies and aspects considered in the project, the concept of cold thermal energy storage (cTES) has been developed. cTES is considered in addition to the cooling system and used when ambient temperature is too high and may lead to turbine efficiency and electricity production reductions. In these conditions, heat from the condenser is partially stored in the cTES and evacuated trough the available cooler when ambient temperature is lower, typically during the night. A prototype of cTES has been built in the CEA site of Cadarache. Experimental results are presented and shows the relevancy of the test loop and of the cTES concept. [ABSTRACT FROM AUTHOR]

The temperatures of the condensers' cooling media (water and air) can vary in a wide range depending on the ship's route. For example, on the route from Odessa to Hopen (Norway), the water temperature changes in the range from 18 ° C to -2 ° C, and air does from 20 ° C to -13 ° C (according to the data for April 13, 2018). Therefore, the well-known recommendations for determining the condensation temperature in the existing calculation methods cannot be applied to a refrigeration unit with composite cooling condensers because they provide different condensation temperature values. To determine the condensation temperature and study the operation of the marine refrigeration unit with composite cooling, a technical-and-economic calculation methodology has been developed. This methodology includes the calculation peculiarities of the composite condenser cooling, the cost of the main refrigeration equipment, the electricity cost and climate data for the ship's route. This method solves the problem of determining the condensation temperature to calculate the condensers and compressors of a marine refrigeration unit. The paper shows the results of the parametric analysis performed for a marine refrigerating unit for the route Odessa – Hopen. The recommended design value for the condensation temperature was 27°C (which corresponds to a pressure of 1066 kPa). It has been proven that the condensation temperature can be precisely determined for a composite condenser cooling at constantly changing cooling medium temperatures, while the technical-and-economic parameters of the refrigerating unit will be optimal. New design values of condensing pressures (temperatures) are obtained to calculate and select heat-exchange surfaces of refrigerating unit's condensers. [ABSTRACT FROM AUTHOR]

This article is devoted to the analysis of arising transient effects in rectification unit operation parameter control systems. Mutual influence of transition processes in hydraulic units and heat exchange units leading to the rectification column operation destabilization is shown. A regulatory control system malfunction connected with the inconsistency of characteristics of new efficient heat exchange equipment and regular centrifugal pump is discussed using practical experience of operation the 1,3-butadiene extraction and purification unit. The coordination and stabilization diagram of hydraulic and heat exchange processes in the rectification control system is described. [ABSTRACT FROM AUTHOR]

The use of the Model Predictive Control (MPC) controller in DME production from synthesis gas has shown better results than the Proportional-Integral (PI) controller. However, this SISO MPC controller makes the DME production process uneconomical due to the cost of expensive MPC controllers. In this study, a Multivariable Model Predictive Control (MMPC 4x4) controller was designed with four manipulated variables (MV) and four controlled variables (CV). MMPC controllers are proposed to reduce the number of controllers used and overcome inter-variable interactions that affect control performance. The design of the controller includes the identification of inter-variable interactions through first-order plus dead time (FOPDT) empirical modeling and controller adjustments. The four CV's include condenser temperature, output cooler temperature, condenser liquid level, and column liquid level, while the four MV's include condenser duty, cooler duty, distillate product flow rate, and bottom product flow rate. The results show that the interactions between the variables identified include all variables involved, so that a 4x4 matrix containing 16 FOPDT models is obtained. The control parameter values in the form of sampling time (T), prediction horizon (P), and control horizon (M) with optimum control performance are 2, 24, and 10. MMPC control performance is better than MPC, which is shown by IAE decline was 19.92% to 72.86% and ISE reduction was 19.16% to 83.58%. [ABSTRACT FROM AUTHOR]

In this study a new multi-generation system, which generates power (electricity), thermal energy (heat and cooling) and ash for agriculture has been developed and analysed. The system consists of a Biomass Integrated Gasification Combined Cycle (BIGCC) and Absorption Chiller (AC) systems. Energy and exergy analysis of this multi-generation system has been conducted, and exergy destruction in system components has been calculated. The results of this study show that 3.4 MW of electricity, approximately 4.6 MW of heat, 88 kW of cooling and 90 kg/h of ash for fertilisation can be generated. The exergy analysis shows that highest exergy destruction occurs in the gasifier and combustor of BIGCC system and in the generator, condenser and absorber of AC system. [ABSTRACT FROM AUTHOR]

The effect of ambient wind on the performance of an air conditioning unit has been experimentally tested based on ISO Standard 5151 (2017). The test was conducted under 35°C dry bulb (db) and 24°C wet bulb (wb) ambient temperature, while the indoor is at 27°C db and 19°C wb. A split air conditioning unit was tested under normal condition and windy conditions. Under normal conditions, the outdoor unit was tested as if no wind in the ambient air. Under windy condition, a constant 6.5 m/s wind was directed 30°, 45°, 60°, and 90° from the outlet side of condenser. The results of the experiment showed the increase of refrigerant discharge temperature and condensing temperature when the condenser was subjected to wind. It is also shown that the supply air temperature increases with the presence of wind. The decrease of cooling capacity by 7.9% is found for windy condition while the power consumption increase by 10.2%. This gives the drop of energy efficiency ratio by 16.5%. Overall, the frontal wind (90° direction) has the most devastating effect on the performance of the air conditioning unit. [ABSTRACT FROM AUTHOR]

In the Heating, Ventilation and Air Conditioning (HVAC) field, condenser water is used to remove heat from the refrigerant cycle and is cooled at cooling towers. Due to the high operating temperatures of 29°C to 38°C, the condenser water cycle is vulnerable to operating issues such as scaling, corrosion and microbiological proliferation; which can be mitigated through either chemical or non-chemical treatment methods. In this paper, the chemical and non-chemical treatment methods for condenser water treatment in the Heating, Ventilation and Air Conditioning (HVAC) systems are compared in terms of efficiency (scaling, corrosion and microbiological proliferation control) and environmental impact. The efficiency of one chemical treatment system (descalant) and three non-chemical treatment systems (Merus Ring, Power Pulsed and Ultra Low Frequency) are investigated by taking condenser water samples from the cooling tower basins biweekly for three months to characterize for pH, water alkalinity, iron content, chloride content, total dissolved solids (TDS) content, electrical conductivity and water hardness, which are compared to the Japan Refrigeration and Air Conditioning Industry Association Standards (JRA-GL-02-1994) and applied to the Langelier Saturation Index (LSI), Ryznar Stability Index (RSI) and Practical (Puckorious) Scaling Index (PSI) to predict the scale formation in condenser water samples. The temperature differences between chilled waters for all systems investigated are recorded to relate the characterized parameters to chiller efficiency. The environmental impacts for all systems investigated are assessed by focusing on the operational stage of all system where the main source of environmental damage is due to the electrical consumption by the HVAC systems. The results yield that all systems investigated comply to the industrial standards. LSI and RSI proved that all condenser waters are saturated with calcium ions but PSI proved that scale formations in the systems investigated are unlikely as the scales are likely to remain dissolved in the condenser water. Consistent temperature differences of chilled water are observed throughout the research period which show that the performance of chillers in each system are optimal, which proves that non-chemical treatment systems are as efficient (in terms of corrosion, scaling and microbial activity control) as chemical treatment system. Environmental impact analysis concluded that chemical treatment system has the highest annual equivalent CO2 emission per cooling capacity of 868.30 kg CO2 e/year RT and that two of the chemicals used causes damage to the aquatic environment. Thus, non-chemical treatment systems have lesser environmental impact than chemical treatment system. [ABSTRACT FROM AUTHOR]

This article presents the results of 3d calculations of the axial-radial diffuser exhaust hood of a powerful steam turbine. The influence of the main geometric dimensions that determines the aerodynamic efficiency of the exhaust hood, on the spatial flow pattern in the exhaust hood flowpath (last stage - diffuser - exhaust hood case) is shown. Calculations were carried out for the inlet velocities field obtained after the row of last-stage blades. The results of calculations of the diffuser exhaust hood for steam turbine with a underslung condenser are given. On the basis of the results of numerical investigation recommendations about the on the choice of the geometric characteristics of the exhaust hood with minimal aerodynamic losses are developed. The work was carried out at the Department of Steam and Gas Turbines of the Moscow Power Engineering Institute. [ABSTRACT FROM AUTHOR]

To enhance the performance of air conditioning (/AC), an ejector as expansion device can be applied to replace the conventional expansion device. The cooling capacity of A/C system influences the diameter of ejector motive nozzle. Meanwhile, the cooling capacity of car A/C system follows the engine rotation. Consequently, the diameter of ejector motive nozzle is not constant in the automotive A/C when the engine rotation changes. The present study determines the diameter of ejector motive nozzle used for automotive A/C system at three difference cooling capacities, i.e. 2.5, 3.5 and 4.5 kW with R134a as working refrigerant. These cooling capacities represent low, medium and high velocities of the automotive respectively. Besides varying the engine rotation, the study also varies the condensing temperatures at 40, 45 and 50°C. The numerical results showed that diameters of ejector motive nozzle for three velocities at the condenser temperature of 40°C are 1.529, 1.809 and 2.051 mm, respectively. Besides lowering input power, the use of ejector also decreases the cooling capacity of the A/C system. However, because decrease in input power is higher than that of cooling capacity, the COP of the system increases. In addition, higher ambient temperature also causes an increase in COP of the A/C. At the condensing temperatures of 40, 45 and 50°C, the COP improvements are 9.38, 22.49 and 33.20%. It indicates that the COP improvement is optimal at high ambient temperature. [ABSTRACT FROM AUTHOR]

Heat pipe is a closed circular tube and the inner section surrounded with wick material. It is operated by working fluid. The working principle of the heat pipe is the heat added on the evaporator section, it causes the working fluid is heated and evaporated. The evaporated vapor flows to condenser section, the vapor rejects the latent heat of vaporization to the surrounding cooling medium and condensed. The condensed fluid flows back to the evaporator section by capillary forces acting on the wick pores. This fluid is again evaporated on the evaporator section, the cycle is repeated. It can transport heat continuously from one location to another location. In the present work, fabricate a heat pipe with the required physical dimensions of length, outer, inner diameter and thickness are 1m, 0.031m, 0.029m and 0.002m respectively. The heat pipe container made up of copper material. The inner section surrounded with wick material of copper screen. The two ends are closed by brazing a copper flat plate. It is filled by working fluid of distilled water. It mainly consists of evaporator, adiabatic and condenser section, each section has a length of 0.4m, 0.2m and 0.4m respectively. The power supplied on the evaporator section by using an external heat source of circumferential band heater. The heat rejected by the condenser surface surrounded with cooling medium of air. The surface and vapor temperature are investigated along the axial length at various time intervals and the time required to reach steady state condition of both the evaporator and condenser section are also investigated. [ABSTRACT FROM AUTHOR]

Heat pipes (HPs) are very efficient heat exchangers. Experiments were conducted to determine the thermal performances of two sintered heat pipes each 1780 mm long x 8 mm OD and 580 mm long x 10 mm OD under power inputs from 30 to 120 W and inclinations from -90° to +90° to the horizontal. Results showed that they performed better with the evaporator above the condenser. Thermal resistances for the long pipes ranged from 0.190 K/W at 30 W to 0.085 K/W at 120 W. For the short pipe, thermal resistance was nearly constant at 0.105 K/W. [ABSTRACT FROM AUTHOR]

The flow developing in water-filled vertical and loop thermosyphons fabricated from glass tubes were recorded using a digital camera. The evaporator section of each thermosyphon was immersed into an electrically-heated water bath. The condenser section was cooled with a fan. Transient flow patterns were observed and recorded from start until the water bath reached boiling point. The observations showed that liquid from the evaporator was forced up towards the condenser section during heating and geysering mostly occurred at large fill ratios. [ABSTRACT FROM AUTHOR]

The best estimation procedure RELAP5 program is used to establish the model of condenser in the floating nuclear power plant. The steady-state calculation of the model of the condenser is carried out, and the dynamic characteristics of the steam turbine under the water stoppage condition are calculated. The calculated results show that error between the steady-state calculation result and design value is small. The model can meet the requirements of condenser thermal performance calculation, which establishes a good foundation for the conventional island thermal system simulation. The pressure of condenser increase rapidly after cutoff of the circulating cooling water, and the alarm pressure of the condenser is reached within 3s. Steam turbine should be unloaded promptly to ensure the safety of the power plant system. [ABSTRACT FROM AUTHOR]

In this paper, an exergy analysis of a heat pump has been performed according to the methodology of V. M. Brodyansky in the North-West Russia conditions. The research has revealed the relationship between parameters of individual elements and general characteristics of the heat pump (HP), depending on the influence of condensation temperature and ambient temperature on the efficiency of each individual element. In the course of the work, the operability, efficiency and losses for the compressor, condenser, evaporator and thermostatic expansion valve (TEV) were calculated. The data characterizing the performance of the heat pump installation (HPI) and its elements under different climatic conditions have been obtained. [ABSTRACT FROM AUTHOR]

SOLWATT project started in May 2018 and involve 9 partners (4 research organizations CEA, CIEMAT, CRANFIELD UNIVERSITY and DLR- and 5 industrial partners TSK, BRIGHTSOURCE, FENIKS, RIOGLASS and TECKNIKER). SOLWATT project is devoted to the reduction of water consumption in CSP power plant. For this purpose, mirror field cleaning, turbine condenser cooling and water recovery are considered. Present paper is devoted more particularly to the cTES industrial prototype (cold thermal energy storage) used to reduce the water consumption related to condenser cooling. The cTES is based on a single-media thermocline storage used to partially or totally store the heat flow from the condenser when ambient temperatures are too high. Storage discharge is performed during the night. A 1000 m3 cTES prototype will be designed and constructed in the 50 MWe La Africana CSP power plant. [ABSTRACT FROM AUTHOR]

Solar distillation is the lowest energy consuming desalination process as it only uses heat from solar radiation. In this study, a solar still is developed to utilize maximum solar irradiation to evaporate water andincrease the rate of condensation by an external condenser. The system is improved by modifying absorber plate with rectangular and triangular channels. This increases surface area of the absorber plate for increasing heat transfer between basin and basin water as well as surface to volume ratio of basin water. To increase condensation of vapor, the effect of an external condenser cooled by feed water is also tested. Feed water flows through the copper tubes of the condenser, cools it and maintains its temperature always below dew point. The condenser also provides extended surface area for condensation when glass surface condensation rate decreases due to excessive film condensation. The water inside tubes of the condenser pick up latent heat of condensation from the vapor condensed on its surface and preheat water. The water is further preheated by solar collector before entering the still. The experiments have been conducted to test the effect of the condenser on overall distillate output against primary glass surface condenseroutput during various temperatures of the glass surface. Different designs of absorber plate are testedfor their effects on rate of evaporation under various hours and weather conditions of several days at Rajshahi, Bangladesh. The maximum average yield obtained is 3.15 L/m2 with triangular channeled absorber plate. The effect of using the external condenser also increased the productivity by 24-30%. [ABSTRACT FROM AUTHOR]

The needs for clean and safe water are growing as the population growing as well. This paper describes the variation of Wastewater Percentage and Pinch Point Temperature Difference (PPTD) on a 50 MW Steam Power Plant. After using the cooling water, not all water is discharged back to the sea, some of the water are used in throttling process where some of water will be vapor, and the other are merged with the water from water treatment and are going to be used for cooling cycle. It’s found that by decreasing the condenser pressure from 8.45 kPa to 6.45 kPa it will produce vapor that could be condense into Aquadest with SEC (Specific Energy Consumption) at best condition as much as 697.85 kJ for producing 1 kg of Aquadest on PPTD 4.3 °C. On that condition, Aquadest could be produced at 0.0178 kg/s rate and the efficiency of turbine increase about 0.16%. Another benefit of this system is that this system discharges cooler water from the process, and has less impact to the environment. [ABSTRACT FROM AUTHOR]

This article reports an experimental study on the energy efficiency of domestic refrigerator with a helical coil condenser (Elliptical configuration with a minor axis 76mm and major axis 381mm) and conventional refrigerator. The Elliptical configuration of condenser coil helps to improve the turbulence of the fluid (both refrigeration and air side). The air side turbulence in elliptical configuration is more than conventional condenser. This increases the heat transfer rate and correspondingly the sub-cooling of the refrigerant after the condenser. The results show that the heat loss is increased in refrigerator B compared to other two configurations and energy consumption per day is decreasing for same operating conditions. [ABSTRACT FROM AUTHOR]

This article sets forth a study to identify and summaries the various techniques for improving the performance (COP) and energy efficiency of the domestic refrigerators. The techniques which are used for improving the performance, such as use of the suction line heat exchanger (SLHX), thermal storage materials (PCMs) and variation in a geometric configuration of the refrigerator condensers. The main purpose of this study to quantify the influence of these techniques for performance and energy efficiency of the refrigerators and to develop an energy efficient refrigerator. The previous results indicate that these techniques have a positive influence on performance and energy efficiency of the refrigerators. This article comments that the use of such techniques can improve the performance (COP) and energy efficiency up to 30% compared to the existing refrigerator configuration. [ABSTRACT FROM AUTHOR]

The practical significance issue of the mobile compressor unit heat losses recovery system development based on the open Rankine cycle without the condenser for improving the unit compactness is considered in the paper. The real climatic conditions of different geographic regions were analyzed in accordance with the average humidity and ambient temperature. The operation efficiency of the mobile compressor unit with the heat losses recovery system in every examined region was estimated. [ABSTRACT FROM AUTHOR]

In the present paper, a multi-objective design optimization of a herringbone wavy fin-and-tube condenser by means of entropy generation minimization technique is presented. The objectives are to minimize the dimensionless entropy generation number associated with the heat transfer with finite temperature difference, and the fluid friction with finite pressure drop as two objective functions using Non-dominated Sort Genetic Algorithm-II (NSGA-II) technique. The results of optimal design are presented in a set of multiple optimum solutions, called 'Pareto-optimal' frontier and a final optimal solution was selected. It was found that both entropy generation rates associated with finite temperature difference and the finite pressure drop of the condenser were in optimum state. Therefore, modeling and optimization of the condenser dimensions have provided an optimal set of values for decision makers to freely select the desired heat transfer surface area and condenser volume by fully considering the specific requirements and constraints of the condenser design. [ABSTRACT FROM AUTHOR]

The effect of pressure drop in the condenser of an air conditioning unit with R410 was simulated under constant swept volume of the compressor. Evaporating temperature and evaporating pressure increase as the pressure drop increases. It causes the decrease of refrigerant density, refrigerant mass flow rate, and refrigeration effect. The enthalpy difference across condenser and compressor, however, increase with the increasing pressure drop. This gives the reduction of evaporator capacity by 25% for pressure drop of 200 kPa. For the same range of pressure drop, the condenser capacity is reduced by 19%, COP is reduced by 27%, and the compressor capacity is almost constant. [ABSTRACT FROM AUTHOR]

This paper analyzes the performance of a split air conditioner at various condensing temperature under the constant cooling capacity. The nominal capacity of the air conditioning unit is 5.06 kW and the refrigerant is R-410a. The simulation shows that the increase of the condensing temperature causes the unit require the higher volumetric and mass flow rate of refrigerant to maintain the constant cooling capacity. The condenser capacity and the work of compression increase as well. On the other hand, the refrigerating effect decreases so that the overall performance of the air conditioning unit decreases. [ABSTRACT FROM AUTHOR]

To improve the thermal safety of a nuclear power plant, a wickless-heat pipe is proposed as a passive cooling system on an emergency cooling tank. Heat pipe will keep the water in the emergency cooling tank on normal operating temperature. The objective of this preliminary research is to investigate the characteristics of the wickless-heat pipe. RELAP/SCDAPSIM/MOD3.4 thermal-hydraulic code was used to analyze the characteristics of the wickless-heat pipe. The simulation results will be used as a basis for designing the future experimental investigations of the proposed wickless-heat pipe. The influence of the hot water temperature in the emergency cooling tank and the mass flow rate of coolant on the water jacket were investigated. The hot water temperature in the emergency cooling tank was varied, i.e. 60, 70, and 80°C. The mass flow rate of condenser coolant in the water jacket was varied, i.e. 2, 4, and 8 L/min. The initial pressure of the heat pipe was -74 cm Hg. De-mineralized water, which serves as heat pipe working fluid, was charged with filling ratio of 80%. The working fluid in the heat pipe can circulate naturally in stable condition if cooling water could absorb the latent heat in condenser. The simulation results showed that for constant hot water temperature, the increasing of condenser coolant volumetric flow rate will decrease the temperature of evaporator and condenser. While for constant condenser coolant volumetric flow rate, the increasing of hot water temperature will increase the temperature of evaporator and condenser. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation on the system performance of a residential air conditioner using condensate as a compressor discharge cooler. The condensate is water produced by the evaporator surfaces. The use of condensate is to reduce the energy consumption and improve the performance of the air conditioning system. The experimental investigation has been carried out on a split-type air conditioner with cooling capacity of 2.5 kW. The utilization of condensate as a discharge cooler decreased the compressor discharge pressure and consequently, reduced the compressor power consumption by 6.3%. In addition, the effect of the decrease in the compressor discharge pressure resulted in the decrement in the temperature of condenser outlet by 2.2°C. The decrease in temperature of condenser oulet leads to the increment in the subcooling and increases in the cooling capacity. [ABSTRACT FROM AUTHOR]

The application of refrigeration condensers combined cooling circuit for reducing fresh water consumption is validated. The insufficiency of existing method of air and water cooling condensers combined circuits calculation is revealed. These circuits result in different values of the recommended condensation temperature (pressure) which does not correspond to a condenser combined cooling operation mode. The condensing temperatures ranges recommended by the known engineering calculation procedures; nature of their mutual change; and the small area having the common solution are graphically shown. The analysis of the known condensing temperature dependences for condensers is carried out and the influence quantities row is defined. The numerical technique of condensation temperature (pressure) determination considering the characteristics and operation modes within a year of evaporator, compressor throttling devices, compressor, condensers, and pipelines is offered. Numerical technique dependences for determination of floating condensation pressure within a year are given. In the given case, the refrigerator economic operation costs will be minimum during the year of refrigerator exploitation. [ABSTRACT FROM AUTHOR]

Storage space requirements with a large refrigeration capacity they use refrigerants types R22 and R404A. This research to develop alternative technologies to meet the needs of storage space with a large refrigeration capacity. Liquid suction subcooling technology is typically used to obtain improve refrigeration effect at vapor compression refrigeration system. Liquid suction heat exchanger subcooling used a type of tube in tube heat exchanger installed between the condenser and the capillary tube before entering the evaporator. Refrigerant used in this research is R22, R404A, and mixture refrigerant R290/R600a [50:50]. In steady state condition with subcooling temperature evaporator with R290/R600a lower reaches -30°C, lower than R404a and R22 is -24°C and -22°C. Liquid suction heat exchanger subcooling effect on ΔTsub. The cooling effect by the mixture refrigerant of R290/R600a greater than R404a and R22, and liquid suction heat exchanger increase refrigeration capacity index (RCI). The average increase in RCI respectively 3.91%, 7.78%, and 11.87%. Work compressor and compressor work index (CWI) with a mixture refrigerant of R290/R600a greater than R404a and R22, the average work compressor and the working compressor index is greatest mixture refrigerant R290/R600a. CWI respectively is an average of 5.68%, 8.82%, and 11.82%. The average COP, their liquid suction heat exchanger, respectively are 3.38, 3.18 and 2.63. COPRS with a mixture refrigerant of R290/R600a [50:50] is bigger than the R22 and R404a, and the average COPRS is 5:01%, 5.95%, and 7:41%. A mixture refrigerant R290/R600a [50:50] have the same characteristics as R404a, which can be used as a substitute for refrigerant R22 and R404A. [ABSTRACT FROM AUTHOR]

A performance analysis based on exergetic performance coefficient (EPC) criterion was carried out for a dualevaporator vapor compression refrigeration system. The influence of the condensing and evaporating temperature on the EPC, the coefficient of performance (COP), the second law efficiency and the destruction of exergy will be presented. It is found that the evaporating and condensing temperatures have strong effects on EPC in the system. Condensing temperature increases will decrease EPC, COP, and second law efficiency, while evaporating temperature increases will increase the EPC, COP, and second law efficiency. The EPC increases and the total exergy destruction decreases with decreasing temperature difference between the evaporator and refrigerated space and between the condenser and ambient temperature. The EPC can be used for selection of optimal design parameters and the procedures given in this paper for exergy analysis of a dual evaporator vapor compression refrigeration systems has been applied to actual systems. [ABSTRACT FROM AUTHOR]

This work deal with experimental evaluation of cooling efficiency of cooling device capable transfer high heat fluxes from electric elements to the surrounding. The work contain description of cooling device, working principle of cooling device, construction of cooling device. Experimental part describe the measuring method of device cooling efficiency evaluation. The work results are presented in graphic visualization of temperature dependence of the contact area surface between cooling device evaporator and electronic components on the loaded heat of electronic components in range from 250 to 740 W and temperature dependence of the loop thermosiphon condenser surface on the loaded heat of electronic components in range from 250 to 740 W. [ABSTRACT FROM AUTHOR]

For optical characterization of nanomaterials, a promising non-interferometric phase-retrieval optical characterization technique called Fourier Ptychography has been demonstrated using Hemispherical Digital Condensers, which uses a set of low-resolution real space images to construct a high-resolution, large field-of-view image of the sample under observation, while simultaneously calculating the experimentally unmeasured phase. The goal of this publication is to discuss experimental and computational studies that reveal causes for diffraction-limited performance of Fourier Ptychography in case of periodically-patterned nanomaterials. [ABSTRACT FROM AUTHOR]

This work investigates the cooling effect of three condensers in the loop thermosyphon in horizontal position. The cooling liquid flows in 1 -tube condenser circuit. The work compares cooling effect of different types of condensers (flat condenser and ribbed tube condenser) at different thermal load. Cooling effect of condenser is connected with thermal changes in the evaporator. We have found out that the higher the thermal resistance is, the lower the condenser output is. Measurements and calculated values have proved different outputs of condensers. [ABSTRACT FROM AUTHOR]

Freeze-drying is a low-pressure, low-temperature condensation pumping process widely used in the manufacture of pharmaceuticals for removal of solvents by sublimation. Key performance characteristics of a freeze-dryer condenser are largely dependent on the vapor and ice dynamics in the low-pressure environment. The main objective of this work is to develop a modeling and computational framework for analysis of vapor and ice dynamics in such freeze-dryer condensers. The direct Simulation Monte Carlo (DSMC) technique is applied to model the relevant physical processes that accompany the vapor flow in the condenser chamber. Low-temperature water vapor molecular model is applied in the DSMC solver SMILE to simulate the flowfield structure. The developing ice front is tracked based on the mass flux computed at the nodes of the DSMC surface mesh. Verification of ice accretion simulations has been done by comparison with analytical free-molecular solutions. Simulations of ice buildup on the coils of a laboratory-scale dryer have been compared with experiments. The comparison shows that unsteady simulations are necessary to reproduce experimentally observed icing structures. The DSMC simulations demonstrate that by tailoring the condenser topology to the flow-field structure of the water vapor jet expanding into a low-pressure reservoir, it is possible to significantly increase water vapor removal rates and improve the overall efficiency of freeze-drying process. [ABSTRACT FROM AUTHOR]

This paper describes the gravity effect on heat transport characteristics in a miniature loop heat pipe with multiple evaporators and multiple condensers. Tests were conducted in three different orientations: horizontal, 45deg tilt, and vertical. The gravity affected the loop’s natural operating temperature, the maximum heat transport capability, and the thermal conductance. In the case that temperatures of compensation chambers were actively controlled, the required control heater power was also dependent on the test configuration. In the vertical configuration, the secondary wick was not able to pump the liquid from the CC to the evaporator against the gravity. Thus, the loop could operate stably or display some peculiar behaviors depending on the initial liquid distribution between the evaporator and the CC. Because such an initial condition was not known prior to the test, the subsequent loop performance was unpredictable. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]