The Revised IEC Standards and Adaptation to the Latest Heat Dissipation Methods

Weighing lysimeters, large-tree potometers, ventilated chambers, radioisotopes, stable isotopes and an array of heat balance/heat dissipation methods have been used to provide quantitative estimates of whole-tree water use. A survey of 52 studies conducted since 1970 indicated that rates of water use ranged from 10 kg day(-1) for trees in a 32-year-old plantation of Quercus petraea L. ex Liebl. in eastern France to 1,180 kg day(-1) for an overstory Euperua purpurea Bth. tree growing in the Amazonian rainforest. The studies included in this survey reported whole-tree estimates of water use for 67 species in over 35 genera. Almost 90% of the observations indicated maximum rates of daily water use between 10 and 200 kg day(-1) for trees that averaged 21 m in height. The thermal techniques that made many of these estimates possible have gained widespread acceptance, and energy-balance, heat dissipation and heat-pulse systems are now routinely used with leaf-level measurements to investigate the relative importance of stomatal and boundary layer conductances in controlling canopy transpiration, whole-tree hydraulic conductance, coordinated control of whole-plant water transport, movement of water to and from sapwood storage, and whole-plant vulnerability of water transport to xylem cavitation. Techniques for estimating whole-tree water use complement existing approaches to calculating catchment water balance and provide the forest hydrologist with another tool for managing water resources. Energy-balance, heat dissipation and heat-pulse methods can be used to compare transpiration in different parts of a watershed or between adjacent trees, or to assess the contribution of transpiration from overstory and understory trees. Such studies often require that rates of water use be extrapolated from individual trees to that of stands and plantations. The ultimate success of this extrapolation depends in part on whether data covering short time sequences can be applied to longer periods of time. We conclude that techniques for estimating whole-tree water use have provided valuable tools for conducting basic and applied research. Future studies that emphasize the use of these techniques by both tree physiologists and forest hydrologists should be encouraged.

The traditional passive heat dissipation method has low heat dissipation efficiency, which is not suitable for the heat dissipation of the concentrated heat source inside the long-focal aerial camera, resulting in temperature level changes and temperature gradients in the optical system near the heat source, which seriously affect the imaging performance of the aerial camera. To solve this problem, an active heat dissipation method of liquid cooling cycle is proposed in this paper. To improve the solving efficiency and ensure simulation accuracy, a dynamic boundary information transfer method based on grid area weighting is proposed. The thermal simulation results show that the liquid cooling method reduces the heat source temperature by 70.12%, and the boundary temperature transfer error is 0.015%. The accuracy of thermal simulation is verified by thermal test, and the simulation error is less than 6.44%. In addition, the performance of the optical system is further analyzed, and the results show that the MTF of the optical system is increased from 0.077 to 0.194 under the proposed active liquid cooling cycle heat dissipation method.

This study was designed to explore whether mucosal fluid evaporation represents a method of heat dissipation from thermal air inhalation injury and to assess laryngopharyngeal tissue damage according to heat quantity changes of dry air and vapour. Fifteen adult male beagles were divided into five groups to inhale heated air or vapour for 10 min as follows: control group (ordinary air), group I (91–110 °C heated air), group II (148–175 °C heated air), group III (209–227 °C heated air), and group IV (96 °C saturated vapour). The heat quantity changes of the dry air and vapour were calculated via thermodynamic formulas. The macroscopic and histological features of the laryngopharynxes were examined and assessed by various tissue damage grading systems. Group IV exhibited the most serious laryngopharyngeal damage, including cilia exfoliation, submucosal thrombosis, glandular atrophy, and chondrocyte degeneration, which is indicative of fourth-degree injury. The quality, heat quantity, and proportional reduction of heat quantity of vapour in group IV were all higher than those in the other groups. Furthermore, we found that mucosal fluid evaporation is not the method of heat dissipation from thermal air inhalation injury used by the airways. Laryngopharyngeal tissue damage depends chiefly on the heat quantity of vapour in the air.

Comparative experimental study on series–parallel heat transfer characteristics of flat heat pipes

Novel heat dissipation design incorporating heat pipes for DC combiner boxes of a PV system

Three-dimensional integrated circuits have higher integration than two-dimensional integrated circuits, and can obtain higher performance and lower power consumption in a certain space. In order to fulfill higher efficiency, thermal management becomes particularly important in 3D integration technology. However, the traditional heat dissipation method cannot satisfy the heat dissipation needs of three-dimensional integrated circuits, which require better heat dissipation methods to be developed. This paper introduces the realization of three-dimensional integrated circuit using silicon via (TSV) technology, which allows the chip to be vertically stacked to transmit information. This paper summarizes the research methods and findings of three-dimensional integrated circuit heat dissipation in recent years, including thermal through silicon via (TTSV) and microchannel cooling. It also emphasizes the advantages and disadvantages of both mehods, and the challenges faced in current research via an overview. The future research trend for both heat dissipation methods mainly consists of combining special algorithms to achieve thermal-electrical codesign and thermal management of three-dimensional integrated circuits.

This papar presents an extensive act of sensible heat (Reynolds flux and dissipation methods) and latent heat (dissipation method) flux measurements from a stable deep water tower and from ships on the deep sea. Operational difficulties associated with ship spray and flow distortion and with sensor calibration, response and contamination are discussed. The influence of atmospheric stability on the dissipation measurements and the bulk transfer coefficients is considered and a parameterization of Z/ L in terms of wind speed and the sea-air potential temperature difference is found to be adequate. Temperature variances, Stanton numbers and w–t cospectra from the Roynolds flux measurements are compared to previous results. The dissipation method is shown to be a viable means of measuring the heal fluxes over the deep sea by comparison with simultaneous Reynolds flux measurements, using our data for the sensible heat and the data of others for the latent heat. The neutral drag coefficient at 10 m height, CDN, because it is relatively well established, is used to check the performance of the shipboard measurements The dissipation sensible and latent heat fluxes are well described, on average, by the neutral transfer coefficients at 10 m height, CTN and CEN, respectively:Previously published results are considered, indicating that 103 CTN = 0.75 may be preferable in stable conditions Some data suggest a slight wind-speed dependency above 10 m s−1, which is mostly accounted for with CTN and CEN proportional to CDN½, as implied by constant roughness lengths A bulk aerodynamic method of estimating the heat fluxes from CDN, CTN and CEN, wind speed, sea temperature, and air temperature and humidity is described and compared to time series of the dissipation method boat fluxes. Potential problem with the data are discussed using the time series.

The traditional heat dissipation methods for base station outdoor cabinets include direct ventilation, heat exchangers, air conditioners, etc. The independent heat dissipation methods have problems such as limited temperature range and poor heat dissipation effect. The system control effect of a new integrated heat dissipation method described in this paper is better than that of the unilateral direct ventilation or air conditioning heat dissipation method, and the maintenance of components such as air conditioners is reduced, and the service life of the air conditioner is increased. After cost comparison, the new integrated cooling system CAPEX may be slightly higher, but OPEX has dropped significantly; energy consumption has also decreased obviously.

Blood purification is one of the commonly used techniques for the rescue of critically ill patients, which is used for acute and chronic kidney injury caused by various causes and renal replacement therapy (RRT) for a variety of critical diseases. Its main working principle is to drain the human blood into a variety of dialyzers through the artificial tube, exchange substances through a variety of ways, and remove harmful substances and some metabolites from patients' body. Then the purified blood is transfused back to the body, so as to maintain the patient's internal environment relatively stable. At present, there are different models of hemodialysis machines in clinical practice, but they are bulky and unable to move, and the method of heat dissipation is single, which cannot meet the needs of hemodialysis treatment in transport patients. Therefore, the medical staff of the Second Affiliated Hospital of Zunyi Medical University designed and developed a hemodialysis machine, which is suitable for patients who demand hemodialysis treatment during transport, and obtained the National Invention Patent of China (ZL 2020 1 0864737.3). The hemodialysis machine comprises a main body of the hemodialysis machine and a mobile vehicle. The main body of the hemodialysis machine is placed in the bottom of the mobile vehicle, and a protective cylinder with fixed airbags is designed around the main body of the hemodialysis machine. The fixed airbag is connected to the air storage tank through the pipeline, the air storage tank is connected to the Venturi tube through the control valve, and the throat of the Venturi tube is connected to the disinfection tank and cooling water tank. The outlet end of the Venturi tube is connected with the cooling pipe inside the main part of the hemodialysis machine and the sprinkler head placed on the top of the main body. By adding a mobile vehicle and designing an airbag and protective cylinder, the hemodialysis machine can be applied to the hemodialysis treatment during the transportation of patients. By designing the heat dissipation pipe, the main body of the hemodialysis machine can be cooled, the temperature of the hemodialysis machine can be reduced, and the hemodialysis machine can still work when the fan is damaged. By designing the sprinkler head, it is convenient to automatically disinfect the main screen and control keys of the hemodialysis machine, reduce the risk of cross infection of medical staff in the operation, and increase the safety and practicability of the hemodialysis machine. The hemodialysis machine is convenient, safe and efficient, which can be widely used in the hemodialysis treatment during transported patient, and is worthy of clinical promotion.

At present, a great accent is placed on the right method of heat dissipation and waste heat recovery. The research work deals with the removal of heat from the internal space of the electrical box. Waste heat generated by the operation of electrical equipment is undesirable for their proper function. The research is focused mainly on the dissipation of Joule's heat and its use is subject to further investigation. The first part describes various methods of cooling electrical boxes and the second part describes our specific method of cooling for electrical boxes. The investigated cooling system operates on the principle of a gravity loop thermosiphon. This type of cooling is an energy and structurally simple method because it is based on a phase change of the working substance. Another advantage is the removal of waste heat without contamination of the interior by external dirt and dust. The work results were obtained experimental on the measuring device. The measurements were performed at different heat loads and at different amounts of working substance in the cooling system. The measurement results evaluation and their comparison provide relevant data about the cooling capacity of the cooling system and indicate which working substance volume is effective at various heat load at the same time.

ABSRACT With the application of higher and higher power density IC in power driver circuits, an efficient modeling method of thermal design and heat dissipation is desired. In this paper, the printed circuit board (PCB) heat dissipation without heat-sink is discussed. Firstly, the thermal resistance of PCB thermal via array is analytically modeled. Then, the optimal via diameter and number are found in a limited area for minimum thermal resistance. Secondly, the radial temperature distribution is analyzed and a method of designing a proper copper pad for heat dissipation under the design power is posed. Finally, computational fluid dynamics (CFD) simulations are developed to verify the posed model and method.

In this work, a new heat dissipation method based on ultra-thin flattened heat pipe (UTHP) is developed for cooling watch-phones. The UTHP with a 0.4 mm thickness was designed to be a three-dimensional shape according to the watchcase shape. The UTHP cooling module (HPM) was soldered by three copper plates and a UTHP. The heat dissipation performance of the copper sheet cooling module (CSM) with the same dimensions was made for comparison with the HPM. The heat dissipation performance of the HPM was experimentally studied. The results indicate that the maximum heat dissipation powers of CSM and HPM were 0.8 and 0.9 W, respectively, at the surface temperature of the ceramic heater not exceeding 65 °C. At this time, ΔTc and Rhc of them were 9.18 °C and 9.86 °C/W, 3.98 °C and 2.63 °C/W, respectively. When the cooling module was cooled naturally from 65 to 37 °C, the heat dissipation time of HPM was 25 s shorter than that of CSM. The UTHP cooling module has a better heat dissipation performance, which can quickly reduce the chip temperature, eliminate the chip hotspot, and solve the heat dissipation issue of watch-phone.

The Lithium battery thermal management system has always been one of the important factors restricting the development of electric vehicles. With the continuous improvement of the performance of electric vehicles, the traditional heat dissipation methods can not meet the needs of today. Therefore, it is necessary to propose new and effective heat dissipation methods to promote the development of the electric vehicle industry. Based on phase change materials and liquid cooling, the thermal management of lithium batteries is simulated and analyzed in this paper. Paraffin is selected as the phase change material, the geometric model is established, and the heat transfer simulation is carried out by using COMSOL software. The effects of condensate flow rate and copper tube arrangement on the heat dissipation of the battery pack are studied, and the influence degree and mode of each factor affecting the heat dissipation of the battery are obtained according to the simulation results. The results show that the spiral arrangement of copper tubes is better than the U-shaped arrangement; When the number of turns of the copper tube is 4, the lithium-ion battery pack has better heat dissipation efficiency; The flow rate of 1.5m/s is more conducive to the heat exchange between coolant and paraffin material.

Sap flow measurements have become integral in many physiological and ecological investigations. A number of methods are used to estimate sap flow rates in trees, but probably the most popular is the thermal dissipation (TD) method because of its affordability, relatively low power consumption, and ease of use. However, there have been questions about the use of this method in ring-porous species and whether individual species and site calibrations are needed. We made concurrent measurements of sap flow rates using TD sensors and the tissue heat balance (THB) method in two oak species (Quercus prinus Willd. and Quercus velutina Lam.) and one pine (Pinus echinata Mill.). We also made concurrent measurements of sap flow rates using both 1 and 2-cm long TD sensors in both oak species. We found that both the TD and THB systems tended to match well in the pine individual, but sap flow rates were underestimated by 2-cm long TD sensors in five individuals of the two ring-porous oak species. Underestimations of 20–35% occurred in Q. prinus even when a “Clearwater” correction was applied to account for the shallowness of the sapwood depth relative to the sensor length and flow rates were underestimated by up to 50% in Q. velutina. Two centimeter long TD sensors also underestimated flow rates compared with 1-cm long sensors in Q. prinus, but only at large flow rates. When 2-cm long sensor data in Q. prinus were scaled using the regression with 1-cm long data, daily flow rates matched well with the rates measured by the THB system. Daily plot level transpiration estimated using TD sap flow rates and scaled 1 cm sensor data averaged about 15% lower than those estimated by the THB method. Therefore, these results suggest that 1-cm long sensors are appropriate in species with shallow sapwood, however more corrections may be necessary in ring-porous species.

Heat dissipation design for lithium-ion batteries