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Heating or cooling systems are of high demand in many industries. Both types of systems are dependent on the geometry. We characterized the CuO-water nanofluid flow, heat and mass transfer through a horizontal channel when additionally heated through the center. The heat is transferred from the cylinder present along the flow. The velocity slip, thermal and diffusion slip effects on the cylinder are studied. The transverse magnetic field is also applied. The Galerkin finite element method is applied to solve the coupled nonlinear governing equations. The results are presented using stream plots and contour plots. The rate of heat transfer is calculated.30% increase in heat transfer rate is observed when the thermophoresis is doubled. Interestingly heat transfer rate is reduced by 40% when the thermal slip is doubled. So the thermal slip is more useful to include in heating or cooling systems as per the industrial need. [ABSTRACT FROM AUTHOR]

Two-phase flow is widely used in the cooling system of electronic equipment, where the heat source is localized. However, two-phase flow may lead to flow instabilities, which have adverse effects on the system such as heat transfer deterioration and vibration. In this study, the effects of related variables on Ledinegg instability in single and parallel channels under localized heat source are investigated. Both models of single and parallel channels have been verified, and the maximum relative error is within ±5%. Based on these two models, the results indicate that the high heating power and low inlet subcooling promote Ledinegg instability, whereas Ledinegg instability is independent of the channel inclination. The average negative slope of continuous heat source, −0.09557, is smaller than that of the heat source close to inlet, −0.07408, which shows the improvement of localized heat source on Ledinegg instability. For the parallel system, when the flow excursion occurs, the total mass flow rate, which is 0.028 kg/s, is equal to two times of the mass flow rate of maximum value in branch pressure curve at which pressure is equal to 0.778 MPa, if two branches are identical. The current work provides qualitative conclusions on how Ledinegg instability will be affected with the change of relevant variables. [ABSTRACT FROM AUTHOR]

An intermittent spray cooling system is applied to fuel cell vehicle heat dissipation using a plate-fin heat exchanger. The effects of various system parameters on cooling performances are evaluated. Experimental results indicate that the cooling performance can be increased by 20% to 80% at various operating conditions and fixed spray area percentage of 45%. An empirical correlation is constructed to characterize heat transfer enhancement percentage. For the 124 data points examined, 92.73% of the data are within 20% of the error range, and 81.8% are within 15% of the error range. The average absolute deviation is 9.30%. [ABSTRACT FROM AUTHOR]

The study of magnetohydrodynamics (MHD) and thermal radiation over‐stretching and shrinking sheets has significant applications in a wide range of fields, from chemical manufacturing to transport engine cooling systems, electronic chip cooling, plasma, the nuclear‐powered sector, saltwater, etc. The present study aims to numerically and theoretically analyze the movement of thermally magnetized Williamson nanofluid owing to an extended/contracting sheet. The regulating flow equations are converted to self‐similar equations through similarity transformation, and then numerically solved by bvp4c using MATLAB software. A comparison of the present numerical study with the published study is quite impressive. The investigation demonstrates that the self‐similar equations disclose the two branches for the limited shrinking factor range. For the stretching case, only one solution exists. As a result, the most fundamentally feasible solution has been determined by the linear assessment of temporal stability. For the aim of stability analysis, the lowest eigenvalue sign indicates the stability or instability of a solution. Through stability analysis, it is witnessed that the first solution (first branch) is stable. Due to the presence of the Lorentz force effect, it is perceived that the velocity curves decline in the whole channel. The point to be noted here is that the velocity of the lower branch compared to the upper branch is higher. The reduced Skin Friction is increased in the first branch and declines in the second branch for the two different values of magnetic factor. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As the global average temperature has increased due to climate change, the use of air conditioning equipment for cooling homes has become more popular. Inverter equipment is advertised as a better energy option than systems with an on/off control; however, there is a lack of sufficient studies to prove this. This work aims to analyze and compare the electricity consumption associated with cooling equipment with an on/off control and inverter equipment. A heat transfer model coupled with energy balance for a room is developed and implemented in Python 3.12. The indoor temperature is controlled by simulating an on/off control and a PID control for the inverter system. Subsequently, the electricity consumption of the two systems is compared, and a sensitivity analysis is performed to determine which variables have the greatest impact on electricity consumption. The results show that the inverter equipment has lower electricity consumption compared to the equipment with the on/off control. However, the sensitivity analysis shows that the indoor temperature set point plays a more relevant role since a 15% variation in its value impacts electricity consumption by up to 77%. [ABSTRACT FROM AUTHOR]

The objective of this paper is to provide the reliable calculation procedure for determining heat and mass flow rates for plate finned tube heat exchangers in dehumidification regimes that can be used easily in engineering practice. For this purpose, the experiments are conducted on two heat exchangers, and datasets for six more heat exchangers are used from literature. Comprehensive database is established with total of 637 sets of data, and it gathers 365 new measurement sets and 272 sets from open literature. The new calculation procedure predicts heat transfer rate and condensate flow rate where new methodology approach (based on the porous velocity, the ratio of characteristic surfaces and hydraulic diameter) is used. Predicted results show 5–10 % deviation for heat duty and up to 20 % for mass flow rate from experimental results, which is of importance to industrial practice. [ABSTRACT FROM AUTHOR]

This study examines the thermal performance of building walls under full sunlight conditions using various insulation strategies. Specifically, it evaluates: (1) the effects of heat on building walls and indoor spaces; (2) the impact of groundwater cooling systems on thermal environments; (3) the influence of phenolic aldehyde insulation layers on heat transfer; and (4) the combined effects of groundwater cooling and phenolic aldehyde thermal insulation. Fluent–CFD (Computational Fluid Dynamics) was used in the study to simulate temperature transmission between the sun, the groundwater cooling system, and both indoor and outdoor spaces. Experimental analysis and simulations reveal that both the phenolic aldehyde insulation layer and the groundwater cooling system effectively reduce heat transfer, with the groundwater cooling system demonstrating the most significant impact. The phenolic aldehyde layer decreases the temperature difference between inner and outer walls by approximately 8 °C. The groundwater cooling system further reduces both inner and outer wall temperatures, helping to maintain cooler indoor environments. Simulation results indicate that, while the phenolic aldehyde layer effectively prevents external heat from penetrating into the room, it does not eliminate heat accumulation. In contrast, the groundwater cooling system efficiently dissipates heat, mitigating this issue. Groundwater analysis shows that maximum temperature differences occur at specific times of the day, with water flow effectively cooling the space. The combined use of the phenolic aldehyde insulation layer and the groundwater cooling system offers superior thermal performance. The phenolic layer provides effective heat blocking, while the groundwater system facilitates heat dissipation, optimizing indoor temperature and reducing air conditioning loads. This combination enhances overall comfort and energy efficiency, with the groundwater cooling system benefiting from reduced flow velocity and lower energy consumption. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the increasing demand for heat dissipation of engineering vehicles, a dual-cycle cooling system is introduced in this paper to prevent the adverse effects of engineering vehicles' equipment when operating at the overheating temperature. The performance of the new system is analyzed through tests, and the results show that the dual-cycle cooling system can meet the thermal balance requirements of the engineering vehicle during the shovel operation. Compared with the traditional cooling system, the new cooling system improved performance in terms of volume, engine energy consumption and working oil efficiency. The oil consumption of a wheel loader using the dual-cycle cooling system is reduced by 1% per hour, and the temperature of its transmission oil and hydraulic oil is reduced by more than 10 °C. The new cooling system has bright future in energy saving and emission reduction of engineering vehicles. [ABSTRACT FROM AUTHOR]

This article presents modeling results and a comprehensive analysis of evaporative cooling systems designed for electric motors using the refrigerants R744 (trans-critical), R134a, R600a, and R290. This study aims to determine the most suitable refrigerant for use in a cooling system, optimize the system design, and calculate the maximum achievable motor power while adhering to specified temperature constraints. The modeling was validated by an experimental setup, which had the cooling system's configuration featuring three circuits for motor housing, stator, and rotor cooling, respectively. The modeling of an evaporative system was used to present the cooling efficiency under varying loads and external temperature conditions. Mathematical modeling encompasses complex algorithms to simulate heat transfer phenomena, accounting for fluid dynamics and refrigeration cycle dynamics. The analyses revealed trends in winding temperature, rotor temperature, air temperature inside the motor, heat transfer coefficient, coefficient of performance (COP), and motor power across different operating conditions while using different cooling refrigerants. The maximal heat transfer coefficients were calculated for all the refrigerants for winding temperatures in the range from 32 to 82 °C, while air temperature and rotor temperatures were between 42 and 105 °C and 76 and 185 °C, respectively. Lowering the evaporation temperature of the coolant to −35 °C resulted in a significant decrease in the winding temperature to 15 °C, air temperature to 38 °C, and maximum rotor temperature to 118 °C at a motor power of 90 kW. Refrigerant R744 emerged as a promising option, offering high heat transfer coefficients and achieving high motor power within temperature limits. At the same time, the COP was lower when compared with other working fluids because of the high ambient temperature on the gas cooler side. [ABSTRACT FROM AUTHOR]

The uniformity of flow distribution within the evaporative cooling plate is essential for its heat transfer performance, given its role as the core component in the pump--driven two-phase flow cooling system. Nevertheless, traditional technical methods employed to achieve uniform flow distribution, such as using an external head and an internal large-diameter sump, lead to a cold plate with excessive volume and weight, rendering it unsuitable for numerous engineering applications. In response to these challenges, this paper introduces a novel flow distribution structure that integrates a spoiler column with a sump. Numerical simulation is utilized to examine the flow distribution characteristics of this structure. The study examines the influence of factors, including the inlet and outlet positions, sump width, and spoiler column distribution, on the flow distribution characteristics. The findings suggest that, for micro-channel cold plates, achieving a more uniform flow distribution is possible by positioning the inlet and outlet closer to the center of the sump. An increase in the sump width proves effective in reducing the non-uniformity of the flow distribution. Furthermore, the addition of a spoiler column at both the inlet and outlet positions results in a significant reduction in non-uniformity. Alternatively, adding a spoiler column at the inlet alone can also yield positive results. Overall, among the eight working conditions analyzed in this paper, the cold plate exhibits a maximum reduction of 80% in overall flow distribution non-uniformity. [ABSTRACT FROM AUTHOR]

Adsorption chiller dynamics and its effect on the performance are greatly influenced by the adsorbent particle size because they govern both the micro (intra-particle) and macro (inter-particle) heat and mass transfer resistances within the adsorber bed. The net effect of adsorbent particle size and shape on the overall cooling system performance is addressed here. Initial CFD analysis of columnar adsorber bed with silica gel + water as the working pair, assuming uniform spherical adsorbent, showed increased uptake capacity with smaller sized (0.23 mm radius) particles over bigger sized (0.8 mm radius) ones despite smaller vapor penetration depth of the former. Subsequently, the effect of adsorbent particle size and shape on the overall cooling system performance is investigated experimentally in a single-stage one-bed mode for RD 2060 (0.8 mm radius) and RD 3070 (0.23 mm radius) silica gel specimens. Though the smaller size of RD 3070 is favourable for the adsorption kinetics at the particle level, its non-spherical shape and highly non-uniform size distribution resulted in significantly lower permeability and thermal diffusivity of the packed adsorber bed, thus hindering the cyclic steady state throughput. For the same operating conditions, RD 2060 and RD 3070 yield a cooling capacity (CC) of 107 W and 22 W, respectively. Further, the coefficient of performance (COP) drops by 73% in the case of RD 3070. The present study indicates that the adsorber bed design must consider both the adsorbent size and shape, in addition to other system operational parameters to enhance performance indicators. [ABSTRACT FROM AUTHOR]

To maintain the concentrated photovoltaic systems (CPV) output, effective cooling is necessary. In contrast to costly and complicated active cooling methods, passive cooling is static, simple, and maintenance-free. Among passive techniques, Heat Pipes (HPs) are devices that efficiently transfer heat from the evaporator to the condenser. The inclination angle of wicked, liquid-filled HP's long-axis determines how well it cools, as an effect of the gravitational force acting on the condensed liquid. This study investigates the effect of tilting the HP long-axis on the performance of the different parameters of the CPV, which is passively cooled by thermal attachment to its back side. Two similar HPs except for their lengths were attached alternatively. Different concentrated illumination levels are then allowed to be incident on the CPV. At each illumination level, the inclination of the HP long-axis was varied from -90 deg (completely vertical with condenser up) to 90 deg (completely vertical with condenser down), passing through 0 deg (HP is completely horizontal) with a step of 15 deg. The effect of such variations on the inclinations has been tested on the two systems. The system incorporating the long HP was found to have a higher cooling performance at an angle of -15 deg, compared to the short HP system, which has its highest cooling capacity at an angle of -60 deg, with an increase of about 7% for the maximum power in case of using the former system compared to the latter. [ABSTRACT FROM AUTHOR]

It has been proved that due to addition of nanoparticals to the refrigerant results in improvement in thermophysical properties and heat transfer characteristics of the primary refrigerant, which improves the COP of the refrigeration system. In this experimental analysis of vapour compression system, the performance study has been carried out by preparing the nanolubricant. In this experimental study, three cases are considered. The compressor of the system filled with pure polyolester (POE) oil, SUNISO-3GS oil and POE + TiO2 nanoparticles as lubricant. In the nanolubricant, the volume concentration of the nanoparticles is 0.2%. The experimental study shows that vapour compression refrigeration system works smoothly with nanorefrigerant. In this experimental study, it has observed that when nanolubricant used in place of traditional POE oil, the refrigerating effect has been increased and the compressor power consumption has reduced by 27% and the refrigeration system COP improves by 29%. The analysis shows that the enhancement factor in the evaporator is 1.2 when nanorefrigerants are used instead of pure refrigerant. The properties of refrigerant like thermal conductivity and density are also studied for the nanolubricant by using the Labview software, in which the thermal conductivity and the density of R134a and nanolubricant mixture are observed higher in comparison with the R134a and pure lubricant mixture. [ABSTRACT FROM AUTHOR]

In this study, we present a new mixed cooling system that combines internal oil with water-cooling, and the effective temperature control of the motor resulted in long-term stable operating conditions. Mass, momentum, and energy equations were obtained by adopting the volume of fluid and moving reference frame methods for an in-depth heat transfer analysis of motor cooling systems. In addition, various cooling systems, such as churning and drop methods were carefully selected by considering the maximum temperature and heat transfer path of the advanced motor. To ensure the reliability of the computational model, the internal thermal resistance of the motor was adjusted based on the analysis results of the reference case. The churning effect facilitated heat transfer through the air gap, thus minimizing the local temperature difference between the rotor magnets and stator coils. The drop effect directly cooled the end coil, thereby resulting in a high cooling efficiency. [ABSTRACT FROM AUTHOR]

As the water pipe cooling system is widely applied to controlling temperature in mass concrete structures, the precise simulation of the temperature field in mass concrete with cooling pipes embedded is meaningful. This paper presents an isogeometric analysis (IGA) with NURBS for heat transfer in mass concrete with consideration of the cooling pipe. The proposed method not only achieves the same level of accuracy with fewer nodes but also eliminates the time-consuming process of mesh in the traditional FEM. The coarsest parameter space which depicts small pipe and large concrete precisely is constructed to create an efficient model for numerical computation. In addition, the unique k-refinement in IGA is supposed to be the most appropriate encryption mechanism, and the knot insertion vector for effective refinement is calculated by considering the characteristics of temperature gradient distribution around the cooling pipes. In addition, a different calculation parameter has been discussed to show the stability and flexibility of the IGA. The obtained numerical results demonstrate the accuracy and efficiency of the proposed scheme in the simulation of transient temperature fields in concrete structures with cooling systems. [ABSTRACT FROM AUTHOR]

• The experimental research of 2-FTE and 6-FTE were developed. • The effect of the number of fins, the angle of the fins and the way the fins are connected to the tube on the performance of the fin evaporator has been studied. • The influence of different fin structures on the cooling capacity per unit mass is analyzed. • The influences of different fin structures on heat transfer coefficient and fin efficiency were analyzed. Tube evaporators are widely used in cold storage, the single-tube two-fin tube evaporator (2-FTE) has the problems of poor heat transfer performance and low tube utilization. In this paper, a numerical simulation method is used to optimize the structure of 2-FTE, and a single-tube six-fin tube evaporator (6-FTE) structure is designed to achieve an increase in the cooling capacity per unit mass of the tube and heat transfer efficiency. Based on this, the heat transfer performance test bench of the tube evaporator is constructed, and the heat transfer performance of 2-FTE and 6-FTE is compared and tested according to the evaluation indices of cooling capacity, fin efficiency and cooling rate in the test environment from −32 °C to −6 °C. The results show that 6-FTE saves between 10.6 and 17.1% of tube consumption compared to 2-FTE for the same cooling capacity. The cooling capacity per unit tube length of 6-FTE increased by 43.9–64.7%, the cooling rate increased by 28–41%, the overall fin efficiency increased by 3.5%, and the heat transfer performance was better than that of 2-FTE, which was consistent with the simulation conclusions and in line with optimization goals. Therefore, the 6 FTE structure proposed in this paper can be an effective solution to save the manufacturing costs of refrigeration equipment for cold storage. [ABSTRACT FROM AUTHOR]

This study presents a unique forced flow and heat sink cooling system and technique for a single-phase immersed cooling system. Computer systems can use electricity more effectively if electronics cooling systems are done more appropriately. Computers and other electronic devices could be cooled via immersion cooling by immersing them in a thermally conductive liquid or coolant. The CPU surface is covered with a straight-fin heat sink, and the mainboard is immersed in NOVESC 3M 649, a designed fluid that can disperse heat while utilizing immersed cooling. The simulation software program results show that increasing the number of fins from 5 to 9 led to an increase in temperature, velocity, and pressure. However, the highest dissipated power was obtained when using eight fins; therefore, increasing the number of fins is considered ineffective due to the increasing temperature. [ABSTRACT FROM AUTHOR]

Nanofluids are engineered materials which are basically colloidal substances prepared by the dispersion of metallic/metallic oxide nanoparticles into a suitable base fluid. The two different phases in nanofluids (solid and liquid) result in entirely different thermophysical properties from the separated phases. The properties exhibited by nanofluids have inspired the researchers to analyze them under a variety of backgrounds. The effectiveness of CuO/water nanofluids in cooling of a smartphone processor is investigated and compared to water in this work. The cross-sectional area for heat dissipation from a processor is obtained from its datasheet. In the first step, numerical analysis is done with water as the medium of heat transfer with a heat flux, and then, experiment is performed using CuO/water nanofluid as heat transfer medium for four volume fractions 0.1%, 0.2%, 0.3% and 0.4% and fluid gap thicknesses as done in the case of water. The heat transfer through nanofluid will be effective only if both the base fluid and nanofluid are in the same mode of heat transfer—either conduction or convection. The mode of heat transfer depends on a number of factors such as temperature, fluid layer thickness, nanoparticle volume fraction, etc. A numerical and experimental investigation on the impact of these parameters is done in this paper using cupric oxide–water nanofluid. It is concluded that the advantage obtained by the increased thermal conductivity of the nanofluid due to the addition of nanoparticles will be offset by the delayed convection onset resulting in a reduced overall heat transfer enhancement when compared to base fluid. Since the convection process is aided by increased temperature, a nanofluid is suitable for enhanced heat transfer under conditions of high heat flux densities and for miniaturized systems where cooling system space is a significant limitation. [ABSTRACT FROM AUTHOR]

This study investigates nonlinear mixed convective hybrid nanofluid flow over a spongy, inclined stretching surface. There are numerous applications of nonlinear convection, and it is especially pivotal in predicting weather patterns accurately and optimizing heat transfer for efficient electronic and industrial cooling systems. The flow is also influenced by the porous behavior of the plate and the presence of the microorganisms. The main emphasis is given to analyzing the influence of thermal and mass Grashof numbers for their nonlinear nature upon the flow system. The equations that administered the flow system are converted to dimensionless notations by using suitable variables. The homotopy analysis approach has been used for the solution of modeled equations. It has been perceived in this work that fluid velocity declines with the upsurge in inertial factor, permeability parameter, volume fraction, and magnetic factor. Thermal profiles upsurge with growth in Brownian, thermophoresis factors, Eckert number, and weaken with Prandtl number. Concentration of fluid increases with progression in the thermophoresis factor and drops with greater values of Schmidt number and Brownian factor. Density number has declined with growth in Peclet, bioconvective Lewis numbers, and inclination angle. Over the range 1≤ Nb, Nt, Ec ≤ 4 the heat transfer rate jumps from 1.8057 to 2.1332 in case of Nb, from 1.8057 to 2.1968 in case of Nt and it jumps from 1.8057 2.3177 in case of Ec that shows maximum heat transfer rate in case of variations in Eckert number. [ABSTRACT FROM AUTHOR]

The present work aims at investigating, numerically, the heat transfer characteristics of transformer cooling system under forced circulation for three different winding configurations. The purpose of a transformer cooling system is to keep the hot spot temperature within the critical value for a long life of transformer, which increases with enhanced cooling of transformer windings. Thus, two different winding configurations are modeled by providing space within the windings (an intra-space model) and in between the windings (an inter-space model) to improve the fluid-solid interaction. A conventional winding, without spacing, is also modeled for comparative study. A 315 kVA, 3-phase core type transformer is taken as the base model from which the winding and core specifications are obtained analytically. Parameters chosen to measure the influence of winding configuration are local temperature distribution in the windings and core and maximum transformer temperature. Results are obtained for all three models with varying space for various cooling mediums like naphthenic oil, silicon oil, and synthetic ester oil at flow velocities ranging from 0.72 m/s to 2.16 m/s. It is observed that the gap between the windings, interspacing, decreases the secondary winding temperatures, while it increases the core and primary winding temperatures. However, the intra spacing configuration finds a drop in local temperatures at all locations of the transformer windings and core. The enhanced heat dissipation to the cooling agent, with intra spacing winding configuration, reduces the maximum transformer temperature. Contrasting to the above, the inter-space model has an adverse effect on maximum temperature at all widths of space considered. Quantitatively, the space within the transformer reduces the maximum temperature by 5% in comparison with the space between the windings. The increased velocity of the cooling medium, Naphthenic oil, from 0.72 m/s to 2.16 m/s reduces the maximum temperature by 4.5 units. The study made to know the role of cooling medium discloses that the synthetic ester oil shows better performance for reducing temperature values due to its highly viscous nature. [ABSTRACT FROM AUTHOR]

The mechanical vapor compression system (MVC) coupled with the evaporative-cooling condenser is an effective method to improve its high temperature adaptability. However, this hybrid systems typically use an evaporative cooler as a single-stage pre-cooling unit of condenser and is mainly designed for hot–dry climates. In this paper, based on conventional evaporative-cooling condenser configuration, three two-stage evaporative-cooling condenser systems (MVC-TSEC(A), MVC-TSEC(B) and MVC-TSEC(C)) were proposed. The MVC-TSEC(A) consists of one condenser and an indirect/direct evaporative-cooler. The MVC-TSEC(B) and MVC-TSEC(C) have two condensers (in series), which are coupled with a two-stage evaporative cooling system. The refrigerant in the MVC-TSEC(C) forms a counter-flow configuration with the outdoor air, while it is concurrent flow in MVC-TSEC(B). Subsequently, the effects of the ambient parameters and outdoor air flowrate on the three two-stage hybrid systems were analyzed comparatively based on detailed numerical models. Finally, the application potential of these hybrid systems was evaluated comprehensively in hot–humid climates. The results showed that the seasonal COP and energy-saving rate for the MVC-TSEC(C) are reached by 4.2–4.7 and 12.7–21.1 %, respectively. Moreover, the static equipment payback period of the three two-stage hybrid systems are 3.8, 3.3 and 3.0 years, respectively. [ABSTRACT FROM AUTHOR]

The layout of multiple natural draft dry cooling towers could have a significant influence on the performance of the cooling system in concentrated solar power (CSP) plants; however, this has never been quantified. Hence, this work used computational fluid dynamics (CFD) modeling to analyze the cooling capacity of two short natural draft dry cooling towers (NDDCTs) on a common site for a range of tower spacings, wind-speeds, and wind incidence angles. The results show that the cooling performance of the towers is a strong function of tower spacing and their orientation with respect to the wind direction. It was found that when the wind came at a 90-deg wind incidence angle (i.e., normal to a line drawn between the two towers), their cooling capacity was improved at tower spacings of less than 1.8 tower diameters (1.8D), though for the other tower spacings, there was no interaction between the towers. However, with the wind at 45 deg to the towers, the flow around the towers resulted in a decrease in their cooling capacity at tower spacings of 1.8D and 2.6D. Most interestingly, it was found that orienting the towers in line with the prevailing wind direction delivered improvements in the cooling capacity of up to 30%. This is due to the windward tower acting as a passive windbreak. Hence, as CSP plant capacity is increased, and additional cooling towers are required, these should be placed close to any existing tower and oriented along the line of the prevailing winds. [ABSTRACT FROM AUTHOR]

The results of physical and mathematical modelling in the ANSYS software package of three-dimensional unsteady coupled heat and mass transfer in the previously developed diamond vacuum window (DVW) of the workstation of the Siberian Circular Photon Source under construction are presented. Previous simulations have convincingly shown: the possibility of using a mini-channel cooling system to implement reliable and proper temperature management of this optical device, the advantage of a mini-channel cooling system over a one channel system in terms of fulfilling the optical requirements for DVW and its design. Here are detailed calculations of unsteady three-dimensional flow in the mini-channels of the cooling system, which will prevent possible dramatic destruction of the workstation due to local overheating of the CVD-diamond foil and its recrystallization. [ABSTRACT FROM AUTHOR]

One of the main trends in the development of the modern electronics industry is the miniaturization of electronic devices and components. Miniature electronic devices require compact cooling systems that can dissipate large amounts of heat in a small space. Researchers are exploring ways to improve the design of the heat sink of the cooling system in such a way that it increases the heat flow while at the same time reducing the size of the heat sink. Researchers have previously proposed different designs for heat sinks with altered fin shapes, perforations, and configurations. However, this approach to optimizing the design of the heat sink results in an increase in the labor intensity of its production. Our goal is to optimize the heat sink design to reduce its size, reduce metal consumption, and increase heat flow. This goal is achieved by changing the number of fins and the distance between them. In this case, there is no significant difference in the geometry of a conventional plate-fin heat sink, and a low labor intensity of production is ensured. A numerical investigation of heat flow and pressure drop in models of plate-fin heat sinks of various sizes and metal volumes was conducted using the ANSYS Fluent software package (v. 19.2) and computational fluid dynamics employing the control volume method. We used the SST k-ω turbulence model for the calculations. The research results showed that by changing the number of fins and the distance between them, it is possible to increase the heat flow from the heat sink to 24.44%, reduce its metal consumption to 6.95%, and reduce its size to 30%. The results of this study may be useful to manufacturers of cooling systems who seek to achieve a balance between the compactness of the heat sink and its ability to remove large amounts of heat. [ABSTRACT FROM AUTHOR]

Indirect evaporative cooling is a technology that can be used sustainably to replace traditional cooling systems using thermodynamic compression cycles, especially in tropical countries like Brazil, which have many regions with hot climates and low relative humidity. These meteorological aspects favor the simultaneous transfer of heat and mass, allowing the thermal cooling effect characteristic of evaporative cooling processes. Thus, this paper investigates the performance of a sustainable air cooling system by combining the psychrometric effects of warm, dry air with the flow features inside a cyclone covered by a layer of a fabric moistened with water. Fluid dynamic simulations previously indicated temperature decreases of up to 12.2 K between the feed and overflow streams of the cyclone. In addition, temperature contours showed that the fluid dynamics of the cyclone provide instantaneous thermal exchange between the walls and the internal fluid. These results directed the study to execute an experimental design using the response surface methodology to evaluate the influence of some variables in the process. The decrease in air stream temperature ranged from 3.9 to 13.1 K, with relative humidity and ambient temperature being the most significant variables. The results also indicated that water consumption to maintain the fabric wet is relatively low since 16·10-3 kg of liquid is required to cool 1 m³ of air flowing through the cyclone. [Display omitted] • High inlet temperature and low relative humidity provided maximum thermal gradients. • Within 0.75 s, in average, the system provided a thermal reduction of up to 13 K. • The thermal efficiency of the wet-bulb for the new system varied from 54.8 to 67.8 %. • Dimensionless numbers for psychrometric cooling system showed a linear behavior. [ABSTRACT FROM AUTHOR]

• Innovative passive cooling system to reduce refrigerator energy consumptions. • Use of external air for condenser cooling enables a lower temperature heat source. • The heat from the condenser drives natural airflow circulation of the external air. • CFD analysis optimize device geometry and heat transfer. • Experimental test demonstrates significant energy savings of 36.0 % ± 5.2 %. The paper presents a solution aimed at enhancing the cooling efficiency of domestic refrigerators. The proposed approach involves a passive cooling system designed to leverage the colder external air during winter for the cooling of the fridge condenser. Indeed, the use of a colder external source helps to increase the efficiency of the refrigerator. The system provides a connection between the rear section of the refrigerator and the external environment via two ducts. The heat dissipated by the condenser induces the natural circulation of outdoor cooling air. The study includes experimental and CFD analysis. The experimental results shows that the configuration with the cooling system achieves higher useful effects and lower power consumption compared to the traditional setup, yielding a reduction in energy consumption of 36.0 % ± 5.2 % when operating with an external air temperature of 0 °C. The CFD model is validated through experimental data, and simulations are conducted to optimize the sizing and design of the system components. Parametric analysis indicates that duct diameters of 12 cm and a box depth of 15 cm behind the fridge are required to optimize heat transfer and aid natural circulation. In summary, the paper offers a suitable solution to increase the fridge efficiency in cold climatic locations. [ABSTRACT FROM AUTHOR]

The utilization of cold plate radiators as a prevalent method for indirect liquid cooling has been extensively investigated and implemented in server cooling systems. However, there is a lack of comprehensive study on the application of this technology at the chip size, indicating a need for more development and exploration in this area. A proposal was made for a grid-channel chip cold plate heat sink to facilitate the dissipation of heat from a chip. tests were conducted to investigate the impact of the flow rate of the cold plate and the layout of the inlet and outlet on various thermal parameters, including the average temperature, maximum temperature, thermal resistance, and uniformity coefficient of the cold plate. The tests were specifically conducted under a chip power of 150W, and the accuracy of the simulation was confirmed through the use of FLUENT. The findings indicate that the cold plate effectively regulates the temperature of the chip, ensuring it remains below 85 °C throughout all experimental groups. In contrast to the single in single out configuration, the single-in multiple-out layout exhibits a higher degree of temperature uniformity within the cold plate. Nevertheless, it is important to note that augmenting the quantity of exits does not guarantee an improvement in heat transfer efficiency. This outcome is contingent upon the presence of a longitudinal flow channel shared by the outlet and intake, as well as the dispersion characteristics of the outlet. Enhancing the dispersion of the exit can significantly enhance the thermal transfer efficiency of the cold plate. Furthermore, a strategy for adjusting the aperture of the orifice is proposed as a solution to address the challenges related to flow uniformity and the issue of high pressure drop in the cold plate. [ABSTRACT FROM AUTHOR]

• The experimental investigation on condensation heat transfer coefficients of R1234yf and R32 inside small diameter microfin tube. • A new general correlation of condensation heat transfer coefficients inside microfin tubes has been developed. • The new correlation could broadly be applied to horizontal microfin tubes with inner diameters between 2.5 and 8.8 mm. • The proposed correlation can be applied to a wide range of mass velocities and many kinds of refrigerants. This study investigated the condensation heat transfer characteristics of the pure refrigerants R1234yf and R32 in a microfin tube with a small diameter of 3.5 mm outside diameter and 3.18 mm inner mean diameter. Experiments were carried out at mass velocities between 50 and 200 kg m -2 s-1, saturation temperatures of 20 and 30 °C, and vapor quality between 0 and 1. The effects of vapor quality, mass velocity, saturation temperature, and refrigerant properties on condensation heat transfer characteristics were investigated. A new correlation is also developed to predict condensation heat transfer coefficients that can be applied to horizontal microfin tubes with inner diameters between 2.5 and 8.9 mm. The new correlation is validated with the database containing 1240 experimental data points from 10 independent research groups. The comparison results show that the three existing correlations overestimate the heat transfer coefficient data with mean deviation greater than 30.0 %. Meanwhile, the new correlation predicted the present experimental data and other researchers' data with mean deviation of 19.8 %. [ABSTRACT FROM AUTHOR]

To mitigate the temperature distribution gradients on the surface caused by the coolant flowing and heating on both sides, an efficient liquid cooling system is needed to solve the problem of high temperatures in localized regions of the heating surface. A copper foam-based vapor chamber composite cold plate is developed, and its heat thermal performance is experimentally investigated. The evaporation base with the copper foam metal wick is placed on both sides of the cold plate to form vapor chambers. The effects of a range of heating powers and coolant flow rates on the thermal resistance of vapor chambers with different filling ratios on both sides are investigated. The results show that a 0.15 L min−1 coolant flow rate provides excellent heat dissipation, and continuing to increase the flow rate has little impact on the temperature uniformity. The vapor chamber's 70 % to 80 % filling ratio reflects the best performance in the test heating power range. The structure is easily assembled and suitable for utilization in battery thermal management systems. [ABSTRACT FROM AUTHOR]

Air-conditioning of buildings is more energy-consuming with widely used vapour compression refrigeration systems in hot and humid areas. Alternatively, evaporative cooling does not show much effect in sultry regions because of increased humidity despite the minimum energy consumption. Indirect evaporative cooling is a promising alternative to direct evaporative cooling systems, but it suffers from low cooling effectiveness and is unsuitable for highly humid regions. Considering the above facts an alternative liquid desiccant-assisted modified M-cycle cooling system is proposed and examined numerically in the present work. The proposed cooling and dehumidification system is a simple unit incorporating chemical dehumidification and regenerative evaporative cooling in a single unit. A simultaneous heat and mass transfer model is developed for the numerical analysis. The numerical code is written in MATLAB and is validated with results available in the literature. Further, numerical analysis was carried out for the effect of various parameters on the performance of the proposed cooling system. The study shows an improvement of 19.2% in dew point effectiveness by incorporating an intermediate opening in the plate separating the product air and working air channels. [ABSTRACT FROM AUTHOR]

The thermal interaction between cooling facilities and the ground is most often discussed in terms of the appropriate insulation of building partitions. Unfortunately, there is little information about the potential of using ground thermal accumulation to support the shaping of the microclimate in cooling facilities by embedding them in the ground. This problem is particularly important in the context of striving to reduce the energy demand of buildings. The article discusses a new scientific problem related to the effect of vegetable cold storage floors being recessed into the ground on the surrounding land's impact range and on its energy management. Validation of the numerical model was performed based on actual year-round field surveys. These surveys were conducted in a free-standing vegetable cold storage facility located in southern Poland. The results of the study allowed us to determine the contribution of the land to the energy balance of the cold storage. A floor recessed into the ground doubled the ground's contribution to the energy balance. The most important research results showed that the range of thermal impact on the surrounding ground also increased by 2.0 m more than that of a building with the floor located at ground level. An evaluation of the heat flow between the cold storage and the ground in the cases analyzed was also carried out. The analysis of the ground heat exchange balance on an annual basis showed high energy gains of 2055 kWh. The total energy demand for cooling was 1723 kWh, while it was 1204 kWh for heating. The results of the analysis of the heat exchange intensity between the indoor air and the ground showed that the ground contribution accounted for 16.6% of the total energy balance of the cold storage. The highest energy gains from the ground were found in October and amounted to 478 kWh. Due to the summer shutdown, there was an intense heat flow to the ground in July, which amounted to 588 kWh. [ABSTRACT FROM AUTHOR]

Surface heat exchanger is extensively used for sustainable development in energy systems. In the surface heat exchanger, the heat transfers from hot flow to cold flow through separating solid surface. The heat transfer area of surface heat exchanger is usually constant when it is performing in energy system. Similarly, fixed plate heat exchanger is applied in electronic outdoor cabinet. In this paper, a novel approach to vary the heat transfer surface in heat exchanger is proposed. A blown plate heat exchanger is introduced for cabinet cooling system. The blown and fixed plate heat exchangers are compared. The heat transfer performances of the blown plate heat exchangers are the same with fixed plate heat exchanger for the same Reynolds numbers. For different Reynolds numbers, the blown plate heat exchanger with all mixed plates has the best performance and the temperature reduction of hot air is arrived 15.185 K, when the maximum temperature difference is 20 K. [ABSTRACT FROM AUTHOR]

PT. Petrokimia Gresik, established with a construction contract on August 10, 1964, stands as Indonesia's most comprehensive fertilizer factory. The company comprises various departments, including the Production Department IIIA, specializing in Phosphoric Acid Production. The objective of assessing the efficiency of a shell and tube cooler-type heat exchanger is to evaluate its performance, determining compliance with design specifications and identifying the need for cleaning and maintenance. The utilized heat exchanger, of the shell and tube type, employs water as its cooling source. According to design calculations conducted between September 13 and September 18, 2023, the expected efficiency of the cooler-type heat exchanger is 91.44%. However, actual data analysis over six days reveals a significant drop in efficiency, registering below 50%. A comparison between design and actual data suggests a decline in efficiency for the E-2502 cooler type. The decrease is attributed to substantial scaling in the E-2502 Heat Exchanger, stemming from the cooled P2O5 Acid solution and resulting in deposition during the heat transfer process. Consequently, it is imperative to initiate a cleaning process for the cooler-type heat exchanger to optimize the heat transfer mechanism. [ABSTRACT FROM AUTHOR]

This study investigates a low-temperature three-circuit cooling system for a 55 kW industrial electric motor. The cooling system provides an increase of the power-to-dimension ratio by 63%, together with an improvement in motor performance. The three-circuit cooling system includes water cooling of the housing and stator and air-cooling of the motor's interior. The test results show that the motor efficiency was maintained in the range between 92.5 and 94.5%, with respect to the motor's power. With power increases up to 90 kW, a winding temperature of 67 °C was observed during three hours of operation. This advancement is particularly valuable for vehicles, ships, and aircraft applications, where maximizing power within limited space is crucial. An analysis of the experimental data showed that the cooling system operates at an average efficiency of 79.2%, indicating that roughly 20% of heat was accumulated in the rotor. This leads to a gradual temperature rise, particularly in the rotor, posing a risk of overheating and failure during motor overloads above 90 kW. Enhancing the cooling efficiency within the motor's interior can be achieved by incorporating extra heat exchangers, implementing evaporative heat transfer, and employing water-cooling circuits at lower temperatures. This, in turn, can boost the electric motor's power-to-dimension ratio. [ABSTRACT FROM AUTHOR]

Transformers are the most important elements of electric power systems. Many conditions must be met for power transformers to work properly. One of them is a low operating temperature. This condition will be met if the transformer cooling system is properly designed. One of the components of a cooling system is insulating liquid. The heat transfer coefficient α of liquid determines its ability to cool the transformer. The higher its value, the more effectively the liquid transfers heat to the environment. This article describes the influence of the position of the heat source, which is usually in the windings of the transformer, on the coefficient α value of the insulating liquid. The vertical and horizontal positions of the heat source were analyzed. The coefficient α was analyzed at different points of the heat source. The tests were carried out for mineral oil and various esters. Heat transfer coefficient measurements were carried out for various surface heat loads of the heat source. It has been proven that, in the case of a horizontal heat source, the coefficient α has a value several dozen percent higher than in the case of a vertical source. It has been proven that the coefficient α has different values in different places of the heat source. Regardless of the location, the highest value of the coefficient α occurred in the lower part of the heat source. [ABSTRACT FROM AUTHOR]

This study presents experimental investigations on the optimal design and operating conditions of pulsating heat pipe (PHP) cooling systems for cylindrical 18650 cells in electric vehicles with a special top heating mode. The research explores the effects of various parameters, including the number of turns, working fluid, filling ratio, coolant temperature, and condenser length, on the PHP system's performance. A cylindrical 3D PHP module was designed based on the flat-type PHP experimental results and evaluated as a cooling system for 18650 cells. The study highlights that the number of turns and working fluid significantly influence the PHP system's performance, with methanol identified as the most suitable working fluid. The optimal number of turns for continuous operation was determined to be 8 to 9. The condenser length was found to play a crucial role in enhancing heat transfer efficiency. The PHP system's continuous flow of working fluid ensured stable temperature profiles and prevented overheating. The research recommends a 9-turn PHP system with methanol as the working fluid and 10 %–15 % filling ratio for cooling two 18650 cylindrical cells. Maintaining cooling water temperature below 25 °C and considering specific orientation angles further improved the PHP system's cooling performance. Overall, these findings provide valuable insights into the optimal design and operating conditions of PHP cooling systems for electric vehicle batteries, leading to stable and efficient cooling, prolonged battery life, and improved electric vehicle efficiency. These results are vital for researchers and engineers working in the field of electric vehicle battery cooling systems and can serve as a foundation for future studies in this area. [ABSTRACT FROM AUTHOR]