How cool pavements reduce urban heat island?5 answersCool pavements reduce the urban heat island (UHI) effect by decreasing surface temperatures through various mechanisms. They achieve this by enhancing radiative properties, such as solar reflectance and thermal emissivity, performing evaporative cooling, and converting heat to other forms of energy. Cool concrete materials, including pavements, roofs, and tiles, reflect sunlight in both the visible and near-infrared (NIR) regions, effectively reducing surface heating and overall temperatures in urban areas. Studies have shown that integrating cool pavements with vegetation can lead to significant reductions in air temperature, surface temperature, mean radiant temperature, and improve outdoor comfort, countering the negative effects of UHIs. Additionally, the use of solar reflective coatings and phase-change materials in cool pavements plays a crucial role in mitigating the UHI effect by balancing factors like bonding strength, reflectance, and durability.
What is the best way to cool down a commercial chip surface?4 answersThe best way to cool down a commercial chip surface is by using a chip cooling system that combines micro-channels with an annular heat pipe to form a two-stage heat exchange system. The micro-channels provide large radiating heat flux and can absorb heat from the chip in a timely manner, while the annular heat pipe utilizes phase change and gravity as a driving force to enhance the radiating efficiency. Another efficient and reliable cooling device is a passive cooling device that uses phase-change of coolant. This device consists of three functional layers including an evaporator, wick, and reservoir, which provide enhanced capillary forces for rapid and continuous heat removal. These cooling methods have been demonstrated experimentally and have shown effective heat dissipation capabilities for chip-level electronics applications.
How can forced convection be used to cool a heat source?5 answersForced convection can be used to cool a heat source by utilizing various techniques. One approach is through thermoelectrochemical conversion, where an electrolyte liquid is forced through a channel formed between two parallel electrodes, with the hot-side electrode simulating the object to be cooled. This method allows for the partial recovery of lost exergy in forced convection cooling, converting thermal energy into electricity. Another method involves the interaction of bubbles with a heated surface, which significantly enhances convective heat transfer rates. The cooling patterns observed in this process are influenced by the interaction between the bubble and the thermal boundary layer, resulting in both enhancement and suppression of heat transfer. Additionally, heat sinks with curved and twisted fins have been developed to address the issue of excessive fin length, improving heat dissipation efficiency. Furthermore, a forced convection heat pipe has been designed with a gas spraying device to improve heat transfer efficiency and condensation efficiency, making it suitable for cooling electronic chips and instrument equipment.
What is the best way to cool down after running?5 answersThe best way to cool down after running is by using a combination of active recovery and cold-water immersion techniques. Taking a 10-minute shower with a water temperature of 25 °C can effectively reduce lower-leg muscle temperature by 2.7 °C. Additionally, walking in cold water for 20 minutes can significantly decrease lower-leg temperature by 11.6 °C. These methods have been shown to be more effective in reducing lower-leg temperature compared to passive recovery or static stretching. Cooling down after exercise is particularly important for maintaining post-exercise dynamic balance, especially in females. Therefore, incorporating a 5-minute cooling down period after intense treadmill running can significantly improve dynamic balance in both males and females.
How technology impact coolness?5 answersTechnology has a significant impact on coolness. The increased similarity of features in technology products has led to a need for unique differentiating factors, and coolness has emerged as one of them. Cool products provide a leap in value and increase a company's market share. The sense of coolness induced by attractiveness, originality, subcultural appeal, and the utility of technology promotes its adoption. Coolness is associated with affectively driven qualities rather than utilitarian ones, and it is equally effective in determining usage intention as usability factors. Technology can also be used to control the behavior of robots, such as seeking cool places based on temperature maps.
How does air cooler reduce heat temperature?3 answersAir coolers reduce heat temperature through various mechanisms. One approach is by evaporating water to generate cool air. The air cooler has a copper thin film that divides the space into evaporating and cooling spaces. Water is supplied to the copper thin film, and when a cooling ventilator is rotating, the water evaporates into evaporation gas, producing cool air. The cooling space cools the air passing through it without increasing humidity, and the cooled air is then supplied into a room. Another method involves improving the flowing state of air flow in the air cooler box by using a runner flow guide plate and reducing interference of turbulent flow. This improves the cooling effect of the air cooler. Additionally, a heat recovery system of a primary air cooler can reduce the temperature of primary air by using low-pressure feed water as cooling water. This reduces the cold blast rate of the bypass of the boiler air heater, resulting in reduced exhaust gas temperature and net coal consumption rate. An air-cooled heat exchanger can increase heat exchange efficiency by spraying water around the heat exchanger, which lowers the ambient air temperature. Finally, an air cooling temperature control cooler achieves high cooling efficiency through a single air source by using a conical air feeding cylinder and a speed change axial flow fan.