Cooling Mode Research Articles

Heat Balance Method of Computing the Cooling Modes of Large-Sized Optics in Vacuum

Heat Balance Method of Computing the Cooling Modes of Large-Sized Optics in Vacuum

Influence of Cooling Modes during Quenching on Structure and Corrosion Resistance of Alloy V-1341T1

Influence of Cooling Modes during Quenching on Structure and Corrosion Resistance of Alloy V-1341T1

Experimental Exergy Destruction Analysis of an Air to Air Heat Pump in Cooling Mode

Experimental Exergy Destruction Analysis of an Air to Air Heat Pump in Cooling Mode

Effect of Working Fluid, Orientation, and Cooling Mode on Thermal Performance of Miniature Flat Heat Pipe

Abstract Flat heat pipes (FHPs) are commonly used as a passive cooling system in portable electronic gadgets due to their compact profile. The present study investigates the effect of different working fluids on the thermal performance of a miniature FHP under different orientations and condenser cooling mechanisms and the start-up performance of FHP. Deionized water, acetone, ethanol, and methanol are chosen as working fluids in the FHP. Five different inclinations (0 deg (horizontal), 30 deg, 45 deg, 60 deg, and 90 deg (vertical)) and two different condenser cooling methods (natural convection and forced convection with fan cooling) are considered in this experimental study. The FHP thermal performance is quantified in terms of overall temperature difference, thermal resistance, and effective thermal conductivity. The results indicate that comparatively higher effective thermal conductivity values are obtained for methanol and acetone heat pipes at low heat loads and under natural convection. At higher heat loads, the ethanol heat pipe had higher effective thermal conductivity values for the same condenser cooling method. For the case of the forced convection cooling mode, the methanol heat pipe had enhanced thermal performance as compared to the other three fluids for all heat load ranges and different inclinations. Due to the higher boiling point of water, as a working fluid water is not suitable in most of the experimental trials except at high heat load under forced convection cooling and in a horizontal orientation. The maximum effective thermal conductivity of 7846 W/mK is obtained for FHP filled with methanol at 24 W heat load and 90 deg orientation under forced convection condenser cooling.

A High-Resolution Analytical Thermal Modeling Method of Capacitor Bank Considering Thermal Coupling and Different Cooling Modes

Thermal stress is of crucial importance to capacitor reliability. However, for a capacitor bank, on spatial scale, the complex heat transfer modes are not clearly illustrated; and on time scale, the ESR aging is neither fully discussed in current evaluation methods. These could lead to a glaring error in the prediction of temperature distribution and lifetime estimation. Therefore, this paper proposed an analytical thermal modeling method with high-resolution for the capacitor bank, considering the thermal coupling effect between individual capacitors, as well as different cooling conditions and the heat variation caused by ESR aging. Firstly, the improved thermal state-space modeling method is proposed to universally describe a multiple heat source system. Then, based on heat transfer and fluid mechanic theories, the characterization method of thermal coupling effect in different cooling modes is discussed. Furthermore, the ESR aging model is applied in the electro-thermal analysis of capacitor bank, aiming to improve the accuracy of thermal calculation in long time scale. Finally, to alleviate the uneven temperature distribution in an in-line designed capacitor bank, a staggered design method is proposed followed by a case study, where a nine-capacitor bank is presented to validate the corresponding modeling method and optimization.

Examination of Energy Efficiency of Air Handling Unit with Integrated Air to Air Heat Exchanger in Cooling Mode

Object of the present study is an experimental determination of parameters, showing efficiency of air handling unit with integrated air to air heat exchanger in cooling mode: effectiveness of supply side of air to air heat exchanger, coefficient of performance and specific fan power of air handling unit. A daily performance of air handling unit in cooling mode is conducted. Effectiveness of supply side of air to air heat exchanger in range of 50.5 % to 74.3 % is received. Coefficient of performance in range of 0.88 to 2.99 and specific fan power of air handling unit in range of 1.77 kW/(m3/s) to 3.06 kW/(m3/s) are received. A relation between effectiveness of supply side of air to air heat exchanger and ratio of heat capacity rates of supply and exhaust air is received. Effectiveness of supply side of air to air heat exchanger depends on values of mass flow of supply and the exhaust air. High values of mass flow of exhaust air responds to high effectiveness of supply side of air to air heat exchanger.

Effect of Cooling Mode on the Microstructure of High-Strength Steel during Hot Rolling

This paper studies the effect of extreme cooling and traditional cooling on the microstructure of high-strength steel during hot rolling by adjusting the cooling process, combining the theoretical calculation and the thermal simulation experiment, and using metallographic microscope, scanning electron microscope (SEM), and electron backscattered diffraction (EBSD) analysis methods in order to solve the problem of coil collapse in the production process of high-strength steel. The research results show that compared with the traditional cooling method, the front-section fast cooling mode can rapidly cool the hot-rolled sheet to the “nose tip” temperature of the ferrite transformation of the time-temperature-phase-transition (TTT) curve, which can promote the transformation of the material to ferrite, increase the proportion of ferrite, and make the grain size of the organization finer. It helps to improve the overall mechanical properties of the material and reduce coil collapse defects. The front-section fast cooling mode achieves good results in industrial application, the proportion of coil collapse reduces from 9.363% to 0.533%, and the problem of coil collapse is significantly improved.

Modeling-Based Energy Performance Assessment and Validation of Air-To-Water Heat Pump System Integrated with Multi-Span Greenhouse on Cooling Mode

The purpose of this study was to conduct a modeling-based energy performance assessment and validation of an air-to-water heat pump (AWHP) system, in the cooling mode, integrated with a multi-span greenhouse using TRNSYS software. We used the building energy simulation (BES) model to investigate the performance characteristics of the AWHP system for greenhouse cooling. We modelled the components of the AWHP system, including the fan coil unit (FCU), water storage tank, and water circulation pump integrated with the greenhouse model. The proposed model included all the components of the experimental system. We validated the proposed model by comparing the simulation results with those obtained from field experiments. We investigated the cooling energy supply to the multi-span greenhouse, greenhouse internal air temperature, heat pump (HP) output temperature, and coefficient of performance (COP). We evaluated the performance of our model by calculating the Nash–Sutcliffe efficiency (NSE) coefficient of all the validated components. Furthermore, we performed linear regression analyses (R2) to determine the relationship between the different parameters. NSE values of 0.87, 0.81, and 0.93, for the greenhouse internal air temperature, the energy supply to the greenhouse, and the HP output water temperature, respectively, validated the prediction accuracy of the model. Moreover, R2 values of 0.83 and 0.39 indicated that cooling loads are more dependent on ambient solar radiation than ambient air temperature. Furthermore, an R2 value of 0.91 showed a linear relationship between the HP’s energy consumption and ambient air temperature. The average daily COP of the HP system was 2.9. Overall, the simulation results showed acceptable correlation with the experimental results. The high NSE values validated the high predictive power of the model. The proposed validation model can be used to improve the performance of systems by optimizing the control strategies and capacities of the equipment (e.g., the HP, the FCU, and the area of the greenhouse). We have provided detailed information to enable engineers, researchers, and consultants to implement the model for their specific needs.

Effect of Minor Sc Addition on the Microstructure Evolution of Al–Cu–Li–Mg Alloy During Homogenization with Different Cooling Modes

Effect of Minor Sc Addition on the Microstructure Evolution of Al–Cu–Li–Mg Alloy During Homogenization with Different Cooling Modes

Investigation of the Operation of Inverter Units for the Possibility of Working in the Cooling Mode at Low Outdoor Temperatures

The possibility of avoiding problems associated with low outdoor air temperatures at the design stage of the air conditioning system of a responsible object is considered. A study was conducted in laboratory conditions to determine the operability of inverter split systems at an ambient (outdoor) air temperature of “minus” 30°C. As a result of field tests in laboratory conditions, the possibility of operating inverter split systems in cooling mode at an ambient temperature of “minus” 30°C is presented.

Effect of a Geothermal Heat Pump in Cooling Mode on the Housing Environment and Swine Productivity Traits

This study compared the effects of the cooling mode of a geothermal heat pump (GHP) system with those of a traditional cooling system (ventilation fans) inside a pig house on the internal house temperature, harmful gas emissions, and the growth performance of the pigs. During the 19-week experimental period, the temperature inside the house connected to the GHP cooling system was significantly lower (p < 0.05) than that of a house with a conventional cooling system. Similarly, the temperature–humidity index (THI) was significantly reduced (p < 0.05) in the GHP cooling system-connected pig house. Furthermore, the concentrations of ammonia (NH3) and hydrogen sulfide (H2S) were also decreased significantly in the GHP-installed pig house (p < 0.05). However, no differences were observed in the concentrations of particulate matter (PM2.5) and formaldehyde (p > 0.05). The pigs reared in the GHP-equipped pig house gained significantly more weight (p < 0.05) by the end of the experiment. The GHP cooling system can therefore be implemented as a renewable, environmentally friendly energy source in pig farms for sustainable swine production without adversely affecting the productivity parameters.

Design and Study of Backup Cooling Mode for Spent Fuel Pool of CPR1000 Unit

In view of the risk of loss of component cooling water (RRI) facing the reactor cavity and spent fuel pit cooling and treatment system (PTR) of the CPR1000 units in China in certain cases, this paper analyzes the problems of the unit PTR from the perspective of single cooling water source, and considering the existing PTR equipment, creatively designs the backup cooling mode using other cooling water sources. As demonstrated by the analysis and study, this design improves the reliability of continuously cooling the spent fuel pool, and the diversity and redundancy of the PTR cooling modes.

Numerical Simulation on Cooling Effect of Working Face under Radiation Cooling Mode in Deep Well

Deep mining results in an increasingly serious hazard. Based on the principle of heat transfer and radiant cooling, a three-dimensional heat transfer model of the working face was established. The influence of the inlet airflow parameter, the surrounding wall temperature and other parameters on the temperature distribution of airflow along the working face were analyzed under the radiation cooling mode. The results show that the increment of airflow temperature in several sections along the working face decreases by 0.67 °C, 0.48 °C, 0.40 °C, 0.36 °C, 0.33 °C, 0.29 °C respectively. The farther away from the airflow inlet, the more obvious the cooling effect was. The airflow temperature of the working face is positively correlated with the airflow inlet temperature and the surrounding wall temperature, and is negatively correlated with the airflow velocity. The research provides a good solution for the working face cooling of deep mines, and also provides a theoretical reference for the research on the radiation cooling technology of the working face.

Regulation of Cooling Mode of Thermoelectric Bloc

With the help of a computational model, the cooling modes of a block of a thermoelectric refrigeration unit designed for ship's provision and freezing chambers are studied. The computational model, based on the numerical solution of a system of nonlinear algebraic equations, takes into account the operating characteristics of a serial thermoelectric module and the thermal resistances of heat removal and supply devices. The dependences of the cooling power and the coefficient of performance of the block on the supply current of the thermoelectric modules are calculated. The analysis of the cooling modes of the thermoelectric block is carried out and recommendations for regulating the current strength depending on the current temperature conditions in the provision and freezing chambers are developed

Experimental Study of Thermal Comfort Based on Driver Physiological Signals in Cooling Mode under Summer Conditions

In this study, electroencephalogram (EEG), photo-plethysmography (PPG), and surface temperature measurements of subjects were taken while performing a driving simulation when the cabin and vent discharge air temperature in summer were changed from discomfort to comfort conditions. Additionally, subjective questionnaires were used to analyze the subject’s thermal comfort under the various driving environments. As a result, the surface temperatures of the forehead, left hand, right hand, and abdomen of the subject during driving were reduced by 2, 0.97, 2.18, and 5.86 °C, respectively, by operating a 12.5 °C vent cooling function at a cabin temperature of 35 °C. As a comprehensive analysis of the subjective survey, PPG, and EEG results, total power (TP), the standard deviation of N-N interval (SDNN), and the root mean square of successive differences (RMSSD) of subjects increased and stress index decreased at cabin and vent discharge air temperatures of 30–27.5 °C and 16.5–18.5 °C, respectively. Furthermore, the relative sensory motor rhythm (SMR) wave and concentration index (CI) of the frontal lobe tended to increase under the same temperature conditions. Accordingly, it was confirmed that these temperature conditions provided a pleasant driving environment for the driver and increased concentration on driving.

Mathematical Modelling and Operational Analysis of Combined Vertical–Horizontal Heat Exchanger for Shallow Geothermal Energy Application in Cooling Mode

Geothermal heat exchangers (GHEs) represent a buried pipe system, which can be utilised to harness renewable thermal energy stored in the ground to improve the efficiency of heating and cooling systems. Two basic arrangements of GHEs have been widely used: vertical and horizontal. Vertical GHEs generally have a better performance in comparison with the horizontal arrangement, and these systems are particularly suitable for confined spaces. Nevertheless, the main technical challenge associated with GHEs, for either the vertical or the horizontal arrangement, is the performance deterioration associated with an increase in the operation times during summer or winter seasons. In this paper, a combined horizontal-vertical GHE arrangement is proposed to address the current challenges. The combined GHE arrangement can be operated in five different modes, corresponding to different thermal loading conditions. These five operation modes of the combined GHE are analysed based on the transient finite difference models previously developed for the horizontal and vertical arrangements. The simulation results reveal that for the single operation mode (horizontal or vertical only), the vertical GHE performs better than the horizontal GHE due to relatively stable ground temperature deep down. While, for the combined operation mode, the series operations (horizontal to vertical or vertical to horizontal) of the GHE are superior to the split mode. It is found that the effect of the fluid mass flow rate ratio is trivial on the heat dissipation of the split mode GHE. The highest heat transfer rate in the split flow operational mode is rendered by the ratio of the mass flow rate of 40% horizontal and 60% vertical. In addition, the climate condition has more effect on GHE’s performance and the increase of the fluid flow rate it can enhance the amount of energy released by the GHE.

Pilot Study on Occupants’ Thermal Sensation at Different Ambient Temperature in Postgraduate Office with Cooling Mode in University Campus

With rapid urbanization, massive amount of energy is required to compensate the electricity usage thus calls for a need to Malaysian government issuing standard MS1525:2014 for temperature settings in office buildings to meet energy efficiency goal. In co-sharing spaces, personal thermal comfort is often not met due to the different thermal sensation at different location inside office rooms. This study was conducted at four postgraduate office spaces with cooling mode in university campus located at Kuala Lumpur to evaluate the occupant’s thermal sensation. We used different set-point temperature of air conditioning ranging from 18.0°C to 28.6°C. The indoor thermal variables such as air temperature, globe temperature, relative humidity, and air velocity are measured at each respondent’s workspace and 200 responses were recorded from ten subjects. The mean value of thermal sensations votes is -0.4 and were within comfort range. 76% of responses voted ‘neutral’ humidity sensation as occupants have adapted to humid condition in Malaysia. The comfort operative temperature found in this study is 24.9°C which indicates that the minimum recommended temperature for energy conservation did not deprive occupants from comfort.

Температурный режим в бассейне выдержки РБМК при нарушении режима его охлаждения

Температурный режим в бассейне выдержки РБМК при нарушении режима его охлаждения

An Empirical Investigation of a Modified Gas Engine Heat Pump in Heating and Cooling Mode for the Residential Application

Gas Engine Heat Pump (GEHP) is found as an effective machine among energy conversion systems. However, further improvement of GEHP performance is still indispensable. In the current study, to recycle efficiently the flue gases waste heat of GEHP unit, it is suggested to utilize a condensing heat exchanger. To assess the performance of the proposed GEHP, an equipped test room was designed. The nominal capacity of the current GEHP is about 80 kW for heating and 71 kW for cooling. The experimental investigation was implemented for two common strategies, i.e. heating and cooling modes. The effect of outlet dry bulb temperature of 0 °C, 5 °C, 10 °C and 15 °C for heating, and 25 °C, 30 °C, 35 °C and 40 °C for cooling as well as water outlet temperature of 40 °C, 45 °C and 50 °C for heating and 8.5 °C, 11 °C, 14 °C for cooling on the performance of the GEHP is investigated. The 95% confidence interval has been considered in statistical analysis. In heating mode, results show that the efficiency of the condensing heat exchanger increases during the reduction of water out temperature and it leads to a Coefficient of Performance (COP) enhancement. Additionally, observation indicates that the decrement of the ambient air temperature from 5 to 0 ° C leads to the severe enhancement of fuel consumption of the gas engine. The performance indicators are re-evaluated using the non-condensing heat exchanger. It is concluded that the COP of GEHP with the condensing heat exchanger decreases by the steeper slope versus the reduction of the ambient dry bulb temperature compared to the non-condensing heat exchanger.

Determination of Thermal Resistances and Optimum Cooling Mode for an Electronic Module used in Electric and Hybrid Vehicles

Determination of Thermal Resistances and Optimum Cooling Mode for an Electronic Module used in Electric and Hybrid Vehicles - written by Sherwin Rajkumar , Sanju Nagendran , Princeton Benedict published on 2020/09/02 download full article with reference data and citations