Air-cooled Condenser Research Articles

Development of Key Components for 5 kW Ammonia–Water Absorption Chiller with Air-Cooled Absorber and Condenser

An absorption chiller is an alternative cooling system that operates using heat from renewable energy sources and employs environmentally friendly working fluids, such as ammonia–water or lithium bromide–water. Given Indonesia’s high solar energy potential, solar cooling systems using absorption chillers are particularly promising. Solar thermal energy has been demonstrated to effectively power absorption chiller systems through both simulations and experiments. In Indonesia, there is significant potential to utilize small-capacity solar absorption chillers for buildings, particularly those employing air-cooled condensers and absorbers, which can reduce operational and maintenance costs. This research aimed to design a prototype of a 5 kW solar-assisted ammonia–water absorption chiller system specifically for residential applications. The system will be air-cooled to minimize space requirements compared to traditional water-cooled systems. The study addressed the design and specifications of the system’s components, dimensional considerations, and an analysis of the impact of the measurement instrument on the research outcomes. The results provide precise dimensions and specifications for the system components, offering a reference for the development of more advanced systems in the future.

Experimental study on the influence of the water spray cooling on air-cooled condenser of the split-type air conditioner

The global installed capacity of air conditioners is increasing causing issues over energy consumption. Due to the significant impact of heat transfer at the condenser on the operation of the air conditioning system, there has been a growing interest in improving this process through evaporative cooling. This study experimentally investigates the impact of utilizing water spray on the condenser to enhance the performance of the 12,000 BTU commercial split-type air conditioner. The findings suggest that, in most cases, the spray system reduces the required cooling time to cool the space from ambient temperature to 25 ° C. The performance is influenced by both the nozzle size and the spraying configuration. This was determined by testing three different nozzle sizes and three different layouts. Comparatively, the diagonal design exhibits superior performance to other designs featuring an equivalent nozzle dimension. Moreover, the condensing unit's heat transfer rate is also examined. The coefficient of performance (COP) is also evaluated. The results indicate that the water spray cooling system leads to a significant COP enhancement up to of 6.16 %. Moreover, the implementation of the water spray cooling technology at the condensing unit can lead to a 40 % reduction in energy consumption.

Exploring the 3E, hydrogen, and ammonia creation potentials of a concentrated solar power (CSP) plant using an air-cooled condenser.

The need to move to more sustainable energy generation has become a major concern among world leaders due to the debilitating effect of greenhouse gases on the environment. Africa has the greatest potential to transition to more sustainable energy sources due to its enormous renewable energy resource potential, particularly solar. This study thus assessed the potential of generating power using a concentrated solar tower power plant (CSTP) at three different locations in Algeria. The study evaluated the system's technical, environmental, economic, and employment creation potential and analyzed the hydrogen and ammonia creation potential using the electricity produced by the CSTP system. Naama, Laghouat, and Ghardaia recorded annual energies of 507 GWh, 502 GWh, and 547 GWh, with capacity factors of 57.6%, 57.6%, and 62%, respectively. A real levelized cost of energy ranging between 7.72 and 8.47 cent$/kWh was obtained. A total of 8530 tons of nitrogen and 1844 tons of hydrogen will be theoretically needed to produce ammonia (fertilizer) for 500,000 hectares of arable land for agricultural activities. In addition, using hydrogen from the CSTP system to produce the estimated ammonia will save 6124.56 tons of CO2 emissions from polluting the environment annually. The creation of thousands of direct and indirect jobs will significantly benefit Algerians. The study concluded with some policy recommendations based on its findings.

A novel dual condensers heat pipe photovoltaic/thermal (PV/T) system: Numerical dynamic modelling and effect factors analysis in dual-function operation mode

This paper presents a dual condensers heat pipe PV/T system with multiple operating modes, including hot water, space heating, and dual-function. To exploiting the system's potential of energy supply, this paper proposes a dynamic model of the system in dual-function mode on the basis of the verified dynamic heat transfer model and condenser distributed parameter model. Several effect factors on the system performance have been analyzed, including water tank capacity, air-cooled condenser area and the dual condensers installation height difference. The simulated results show that the above parameters have little effect on the system's total thermal efficiency but a significant effect on single condenser heat gain distribution. When the water tank capacity increases from 100 L to 200 L, the thermal efficiency of the water-cooled condenser increases from 10.68 % to 17.82 %, while the air-cooled condenser's decreases from 48.12 % to 40.72 %. As the air-cooled condenser area is changed from model 1 to 4, the total efficiency increase from 58.13 % to 71.41 %. The system's thermal efficiency falls from 58.66 % to 47.50 % and its overall efficiency falls from 71.41 % to 60.40 % when the height difference rises from 0 m to 0.7 m.

Bench studies of the influence of operating conditions on operational safety of steam turbine air-cooled condensers at subzero outdoor temperatures

Condensation processes are widely spread in various branches of industrial production and, in particular, in electric power industry, where, according to experts' data, heat removal in thermodynamic cycles of steam turbine plants (STP) operating as part of combined cycle plants (CCP) and autonomously, in the 21st century will be exercised mainly in air-cooled condensers (ACC). At the same time, the use of ACC as a part of steam turbine units operating in climatic conditions typical for the Russian Federation (RF) determines the relevance of problems to be solved to ensure their safe operation at subzero outside temperatures. One of these challenges is to ensure long-term safe operation of the ACC, with the formation of ice on the inner surface of the heat exchange pipes minimized. To conduct the research, Steam Turbine Air-Cooled Condenser research and training stand was used. The paper presents the combined circuit and measurement diagram of the research and training stand, and gives a brief description of the design of the ACC. Experimental modes have been determined, and methods for processing experimental data and analyzing the results obtained have been developed. As part of the study, experiments were carried out on 18 steady-state operation modes of the stand. At the same time, the values of the main operational parameters of the ACС varied within the following limits: the temperature of the cooling air at the ACС inlet — from minus 11,5°C to minus 1,8°C; the cooling ratio — from 176 to 790. The relative weight content of air in the vapor varied from 0,051% to 0,12%. An analysis of the obtained results was carried out, on the basis of which a relationship was established that allows, for various negative temperatures of the cooling air at the inlet to the ACС, to determine the highest value of the cooling ratio at which its long-term safe operation is possible. An algorithm for using the obtained relationship is given.

Modeling and experimental study of air-cooled finned-tube condenser using coupled distribution parameter method and air-side temperature distribution

The air-cooled finned tube condenser (ACFTC) plays a crucial role in refrigeration systems, profoundly influencing overall operational efficiency. Its intricate structure, connectivity, and phase change characteristics pose challenges for numerical simulation modeling. While traditional distribution parameter methods effectively capture flow and heat transfer within tube mediums, they overlook ACFTC’s air-side temperature distribution, resulting in discrepancies between simulated and experimental outcomes. This study enhances existing distribution parameter models by incorporating ACFTC’s air-side temperature distribution characteristics, yielding an improved predictive model for transient operational behavior of both Z-shaped and U-shaped configurations. Dynamic experiments and model analyses were performed on the Z-shaped configuration using a cold storage experimental setup. Results demonstrate the improved model’s accurate prediction of tubing medium outlet temperature and pressure, with maximum deviations of approximately 3 °C and 0.01 MPa, respectively. Notably, the improved model exhibits around a 30 % enhancement in predictive accuracy compared to the existing models for both Z-shaped and U-shaped ACFTCs.

Performance Evaluation and Cycle Time Optimization of Vapor-Compression/Adsorption Cascade Refrigeration Systems

The reliance on more sustainable refrigeration systems with less electricity consumption attracts a lot of attention as the demand for refrigeration increases due to population growth and global warming threats. This study examines the use of a cascade vapor-compression/adsorption refrigeration system in hot weather, focusing on condensing temperatures of 50, 55, and 60 °C, whereas an air-cooled condenser is in use due to practical considerations. A fully coupled transient model is developed using COMSOL Multiphysics to simulate the integrated system, considering the practical limitations of the vapor compression system (VCS) and the dynamic nature of the adsorption system (ADS). The model combines a lumped model for the ADS with the manufacturer’s data for a VCS compressor at different condensing and evaporating temperatures. It was found that the VCS is more sensitive to the change in the ADS’s condensing temperature, since when the temperature is raised from 50 °C to 60 °C, the VCS’s COP decreases by 29.5%, while the ADS’s COP decreases by 7.55%. Furthermore, the cycle time of ADS plays an important role in providing the cooling requirements for the bottoming cycle (VCS), and it can be optimized to maximize the energy conversion efficiency of the VCS. At optimum cycle time and compared to the conventional VCS, the cascade system can boost the cooling capacity of the VCS by 18.2%, lower the compressor power by 63.2%, and greatly enhance the COP by 221%. These results indicate that the application of the cascade VCS/ADS in such severe conditions is a more sustainable and energy-efficient solution to meet the growing need for refrigeration.

Thermal and aerodynamic characteristics of air cooled condenserfor steam turbine power unit

THE PURPOSE. Increased water consumption at power plants leads to a deterioration of the environmental situation not only in countries with limited water supply sources, but also in countries with significant reserves of fresh water. There is a need to consider the possibility of using an air condenser as an alternative use in industrial water supply systems at a power plant. To present a methodology for calculating the main characteristics of a condenser (condensation and reflux sections), to estimate the aerodynamic resistance and fan power for an air-cooled condenser as part of a steam turbine power unit. Determine the influence of air temperature and pressure in the condenser on the calculation of the air condenser. To develop recommendations for the selection of parameters of air condensers operating as part of steam turbine power units. METHODS. Methods for designing heat exchangers, modeling and intensifying heat exchange processes were used in the course of calculating an air condenser unit. RESULTS. A method for calculating an air-cooled condenser for a 110 MW condensing turbine has been developed. The analysis of the calculation of the heat transfer coefficient is given. The analysis of the values of the heat exchange area of the condensing unit is presented. The effect of pressure in the condenser on the main calculated characteristics of the condenser is shown. Recommendations for the selection of the fan capacity in the condenser and the design temperature of the cooling air have been developed. CONCLUSION. The issue of using air coolers in the power industry is still poorly covered in the literature, however, environmental problems and the shortage of fresh water are becoming more and more urgent all over the world. The development of air-cooling systems is a very topical issue for modern power engineering. It is shown that for stationary installations of condensation of water vapor, the most suitable is the hipped-roof arrangement of the heat-exchange sections with the lower arrangement of the fans. Quantitative estimates of the change in the heat transfer coefficient and the area of the heat-exchange surface are given for the pressure range of 8…20 kPa. The power consumption of the fan depends significantly on the temperature of the cooling air and the vacuum in the condenser.

Experimental study of a novel in-tube spray evaporative condenser for geothermal power generation

To enhance the efficiency of medium to low-temperature geothermal power systems, we designed a novel in-tube spray evaporative condenser. Experimental setups for single-tube heat exchange were devised, examining both water-water and working fluid-water configurations. The study analyzed the impact of air volume and hot water flow rate on heat transfer. Economic comparisons were made in laboratory conditions among the novel evaporative condenser, traditional evaporative condenser, water-cooled condenser, and air-cooled condenser. Results indicated: (1) The novel evaporative condenser exhibited 1.5–1.7 times higher heat flux density and 2.0–2.7 times higher mass transfer coefficient, indicating superior heat transfer performance compared to the traditional one. (2) Variations in hot water flow rate within a certain range had minimal impact on condenser performance when the condenser size was constant, providing valuable insights for condenser selection and structural design. (3) Both total power and water consumption of the novel evaporative condenser were lower than the other three types. Its daily operating cost was approximately 3/4 of the traditional evaporative condenser, 1/2 of the air-cooled condenser, and 1/4 of the water-cooled condenser, demonstrating superior economic feasibility.

Natural draft direct dry cooling system performance at various application scales under windless and windy conditions

The natural draft direct dry cooling system (NDDDCS) presents a promising alternative to conventional forced draft air-cooled condensers (ACCs) and indirect natural draft dry cooling systems, overcoming their limitations by efficiently condensing process steam directly and passively. The NDDDCS achieves superior thermal efficiencies while reducing system complexities, operational costs, and auxiliary power consumption. Potential reductions in operational expenses for the system may offset initial capital investments, resulting in lower lifetime costs. While research to date has focused on large-scale NDDDCS performance under varying wind conditions, this work addresses a critical gap by investigating the system’s scalability for various applications, including a large-scale coal-fired power plant (900 MWt, 165 m total height), a medium-scale concentrated solar power plant (CSP) (100 MWt, 65 m total height), and a small-scale water desalination plant (1 MWt, 11.5 m total height) under both windless and windy conditions. To achieve this, a steady-state 3-D computational fluid dynamics (CFD) model is developed, validated and scaled, incorporating innovative features such as an atmospheric pressure gradient and the ability to capture reversed flows through the system’s heat exchangers. Additionally, the model assesses inlet air temperature data at a per-cell resolution, enabling the ability to predict non-uniform temperature distributions in the heat exchangers, including hot-spots caused by airflow recirculation. Analysis of velocity and temperature fields across all scales reveals that recirculation effects negatively impact NDDDCS performance, particularly at the middle circumferential heat exchanger sector. The hyperbolic shape of the tower shell induces internal recirculation zones and reduces the effective flow volume. Under windy conditions, performance losses of 44%, 40%, and 40% are observed at crosswind speeds of 3 m/s, 6 m/s, and 9 m/s for small, medium, and large-scale towers, respectively. Beyond these speeds, the relationship between system performance and draft driving potential becomes non-linear due to crosswind effects dominating. Furthermore, a novel effect is identified at wind speeds of 9 m/s, 15 m/s, and 18 m/s for small, medium, and large-scale systems, respectively, where an inflection point allows for system performance recovery. This study underscores the NDDDCS’s potential as a cooling solution for modern power cycles across various scales, while highlighting the implications of scaling the system for medium- and small-scale thermal applications.

Enhancing Axial Flow Fan Performance in Air-Cooled Condensers: Tip Vortex Manipulators and Comparative Analysis of Numerical Simulation and Experimental Testing

Abstract Direct dry-cooled power plants typically operate numerous large-diameter axial flow fans in air-cooled condensers (ACCs) to facilitate the condensation of steam in the plant's thermodynamic cycle. Enhanced fan efficiency may, at scale, lead to significant parasitic power reductions and subsequent increases in plant power output. The performance of these fans may be increased by adding blade-tip modifications, which act to control blade-tip leakage flow. Previous studies have shown that manipulating the tip leakage vortex (TLV) increases the blade-to-air momentum transfer and stabilizes the air flow structures as it traverses the fan blade. This paper takes a step toward the development of improved tip vortex manipulators for an ACC fan. Three-dimensional computational fluid dynamics (CFD) simulations, and experimental testing of the modified and unmodified fan within an ISO test facility are performed. The results are then utilized to assess the accuracy of the simulation model, visualize the manipulated flow structures at the blade tip, and ultimately quantify the effect of the endplate designs on fan performance. Excellent correlation between numerical and test results for the unmodified fan is observed, and the benefit of blade-tip modification on fan performance is again confirmed experimentally. The simulation model, however, fails to predict improvements in fan performance under modification, and simulated tip leakage flows are investigated for clarification. It is hypothesized that deflection of tip endplates under operation account for differences between simulation and experiment, and that fluid–structure interaction analyses could potentially resolve discrepancies.

Gravimetric and Thermal-Imaging Characterization of Water-Free Reflux Condensers for Laboratory Applications.

Water-free reflux condensers, which use convective cooling from the surrounding air to condense vapors, avoid the need for cooling water, which is more sustainable than water-cooled condensers, and eliminates the risk of flooding, but these devices are newer and less familiar to many chemists, who may never have used them before. To facilitate the shift to water-free condensers, several types of water-free condensers (simple glass tube, Vigreux column, Condensyn, Findenser, and air-cooled Dimroth) were characterized using three different solvents (ethyl acetate, acetone, and tetrahydrofuran) under both gentle and vigorous refluxing conditions to compare their relative performance and determine the condensing capacity/failure point. In addition to experimentally quantifying the performance of each condenser both gravimetrically and via infrared thermal imaging, energy-balance models were developed to gain insight into which factors were most important in driving their performance. Several of the water-free condensers, including the Findenser, Condensyn, and air-cooled Dimroth condenser, were shown to provide suitable performance for most refluxing operations.

A comparative study of latent heat thermal energy storage (LTES) system using cylindrical and elliptical tubes in a staggered tube arrangement

Numerical analysis was performed to compare the thermal and hydraulic performance of the elliptical and circular tube geometries in the prototype-scale latent heat thermal energy storage (LTES) system. A staggered tube array configuration was used for the analysis where the tubes were placed horizontally. Commercial grade hexahydrate calcium chloride (CC6) was selected as a phase change material (PCM) due to its phase change occurring at room temperature. The study included a numerical analysis of the melting and solidification processes of the PCM within the tube array for both tube shapes, employing transient two-dimensional Navier-Stokes equations and a Realizable k-ɛ turbulence model to predict fluid flow and heat transfer. The enthalpy-porosity technique was used to model PCM melting and solidification. Numerical predictions indicate that the thermal performance for both tube shapes is almost indistinguishable during the melting and freezing processes. However, due to the aerodynamic shape of the elliptical tube, the pressure drop across the horizontal elliptical tube array is approximately 80% lower compared to that of the circular geometry. This reduced pressure drop implies that less pumping power will be required to achieve the desired flow rate across the tube bank, leading to economic advantages for the horizontal elliptical tube array. The proposed design can be used as a dry cooling technique employing an Air Cooled Condenser (ACC) in a thermal power plant.

OPTIMAL PROFILE FOR A FIN OF CONSTANT CROSS SECTION WITH MODELATION OF THE THERMOPHYSICAL PROPERTIES

The dependence of the temperature and composition on thermal conductivity of steel, and its influence in the optimal profile for a fin of constant cross section to be used in air cooled condenser is presented. In Air Cooled Condensers (ACC), air is used as refrigerant, which forces the need for fins to improve the heat transfer process leading to appreciable increments in the costs of the installation. Therefore, developing better fins profile will allow optimizing the operation, maximizing the heat transfer and minimizing the manufacturing cost of the fins. To this objective, in the present paper, three geometric parameters, thickness, height and surface of heat transfer of the fin, this parameters influence directly the optimal obtained profile for conditions of maximum heat flux and optimal Biot number. The study was accomplished for fins of constant cross section. In a future work, fins of variable cross sections will be considered.

Design of Sinusoidal Leading Edge for Low-Speed Axial Fans Operating under Inflow Distortion

Axial fans may be equipped with passive flow control devices to enhance rotor efficiency or minimize noise emissions. In this regard, blade designs influenced by biomimicry, such as rotors with sinusoidal leading edges (LEs), have gained popularity in recent years. However, their design is predominantly driven by a trial-and-error approach, with limited systematic studies on the influence of rotor performance. Furthermore, their effectiveness is typically evaluated under controlled conditions that may significantly differ from operations in real installation layouts. In this work, a systematic review of the design process for sinusoidal LE axial fan rotors is provided, aiming to summarize previous design experiences. Then, a modified sinusoidal LE is designed and fitted to a 7.3 m low-speed axial fan for air-cooled condensers (ACCs). These fans operate at environmental conditions, providing a quasi-zero static pressure rise, often with inflow non-uniformities. A series of RANS computations were run to simulate the performance of the baseline fan and that of the sinusoidal leading edge, considering a real installation setup at Stellenbosh University, where the ACC is constrained between buildings and has a channel running on the ground below the fan inlet. The aim is to explore the nonbalanced inflow condition effects in both rotor geometries and to test the effect of the installation layout on fan performance. The results show that the modification to the rotor allows for a more even distribution of flow in the blade-to-blade passages with respect to the baseline geometry.

An Overview of Enhancing the Efficiency of Vapor Compression Cooling Systems by the Implementation of Evaporative Condensers

This paper explores the significance of energy conservation in the context of rising energy consumption and its impact on economic growth. With a focus on cooling systems, particularly evaporative condenser technology, the study aims to investigate its fundamentals, operating principles, and theoretical aspects. The paper delves into the various types of condensers used in cooling systems, emphasizing the role of evaporative condensers in enhancing heat transfer efficiency. The operating principles of evaporative condensers are detailed, considering factors such as air and water flow rates, wet bulb temperatures, and heat transfer coefficients. Theoretical models and mathematical approaches for evaluating evaporative condenser performance are also reviewed. The research includes an extensive review of existing literature on evaporative condenser technology, covering refrigeration models, HVAC systems, and various experimental studies. Theoretical models are discussed, highlighting the challenges in accurately modeling evaporative condenser behavior. The paper also presents achievements and advancements in research, including experiments that demonstrate the positive impact of evaporative cooling on air-cooled condenser systems. Various case studies and experimental validations showcase the potential energy savings and improved performance achieved through the incorporation of evaporative condensers in cooling systems. By switching from an air-cooled to an evaporatively-cooled condenser, one can reduce electricity consumption by 58%, according to research. This alternate condenser type improves performance by 113.4% at from 3 to 3000 kW of cooling power.

Mapping the waste heat recovery potential of CO2 intercooling compression via ORC

The goal of the present work is the systematic mapping of the electricity savings potential of waste heat recovery (WHR) from CO2 compression intercoolers via Organic Rankine Cycle (ORC) technology. Α generalized approach covering a broad range of target CO2 discharge pressures from 50 to 500 bar for 3 to up to 8 compression stages is followed. The maximum, theoretical electricity savings based on the exergy of the heat transfer fluid (HTF) used for intercooling range between 10 % and 24 %. Considering the exergy efficiency of optimized air-cooled ORCs operating with alkanes and hydrofluoroolefins for HTF temperatures between 70 °C and 130 °C, the maximum electricity savings ratio (i.e., the electricity savings compared to the total electricity consumption of the compression unit) is about 5 %, while the installed power of the WHR-ORC ranges from about 3 to 23 kWe per kg/s of compressed CO2. Because of the intense variability of CO2 specific heat capacity over a wide range of pressures, there is a very strong dependence of the waste heat potential on the final discharge pressure and number of stages. Through optimized mixing of the HTF streams, the performance of the WHR-ORC can be improved for particular discharge pressure ranges. Proper sizing of the ORC air-cooled condenser for minimizing air-side pressure drop is critical to ensure the feasibility of WHR-ORCs. According to a techno-economic analysis, WHR-ORCs can result in discounted payback periods from 6 to 12 years and 2.5 to 4 years for 4000 and 8000 operating hours, respectively.

Investigation of the performance of cold-end system in direct air-cooled power units under the influence of ambient winds

Direct air-cooled condensers in power plants rely on heat transfer with the atmospheric environment to discharge thermal energy. The heat transfer process becomes complicated in practical operations when ambient wind is involved. To examine the impact of wind on the heat transfer performance of direct air-cooled condensers, this paper took into consideration three different wind directions, namely, headwind, crosswind and tailwind, as well as four different speeds (3 m/s, 6 m/s, 9 m/s, and 12 m/s), and numerically investigated their influences on the thermal performance of a 600 MW direct air-cooled power unit. The variation in ventilation rates and inlet air temperatures among the cells under the influence of ambient winds are also studied. Simulation results indicated that ambient winds induced thermal air re-circulation and air backflow phenomena in the air-cooled island. The cells located on the windward side were significantly affected in all three wind direction conditions. The ventilation rates and inlet air temperatures among the cells were not uniform, showing an overall increasing trend. In particular, negative pressure zones were generated under tailwind conditions, severely impacting air-flow rates at the fan inlet, and inlet air temperatures of cells. These phenomena became more pronounced with increasing wind speeds.

Metal additively manufactured air-cooled condenser for enhanced thermohydraulic performance

Metal additively manufactured air-cooled condenser for enhanced thermohydraulic performance

Metal additively manufactured air-cooled condenser for enhanced thermohydraulic performance

Metal additively manufactured air-cooled condenser for enhanced thermohydraulic performance