Application of specific heat capacity

Water has great specific heat capacity and is widely used in industrial and agricultural production and daily life. This application mainly considers two aspects. First, a certain quality of water absorbs (or releases) a lot of heat, but its temperature changes little, which is conducive to regulating the climate; The second is that a certain quality of water absorbs a lot of heat (or releases heat) when the temperature rises (or falls), which is beneficial to using water as coolant or heating. The specific heat capacity of water is large, which has a significant impact on climate change. Under the same heating or cooling conditions, the temperature change of water is very small, which has a great influence on the climate. During the day, the temperature in coastal areas is slower than that in inland areas, and the temperature in coastal areas is less at night. Because of this, the temperature in coastal areas changes little in a day, while the temperature in inland areas changes greatly. In a year, the inland is hotter than the coast, and the inland is colder than the coast. When the ambient temperature changes rapidly, the water temperature changes relatively slowly. The high proportion of water in the organism helps to regulate the temperature of the organism itself and avoid serious harm to the organism caused by the sharp change of temperature. The reasons for the formation of land-sea breeze are similar.

1. Temperature effect

According to Xinhua News Agency, after the impoundment of the Three Gorges Reservoir, the world's largest artificial lake will become a natural "air conditioner", making the climate in the mountain city of Chongqing warm in winter and cool in summer. It is predicted that the temperature may drop by 5℃ in summer and rise by 3-4℃ in winter.

2. Relieve the heat island effect

On a clear and windless summer day, the ground temperature on the island is higher than that of the surrounding sea water, thus forming sea breeze circulation and cumulus convection on the island, which is the performance of the ocean heat island effect. The specific heat capacity of water is more than four times that of sand and gravel. Water and sand with the same quality will absorb more heat if they are raised to the same temperature; If the heat absorbed or released is the same, the temperature change of water is much smaller than that of sand and gravel. In summer, the sun shines on the sea. Although seawater absorbs a lot of heat, the temperature of seawater does not change much because of its large specific heat capacity. In the desert, because the specific heat capacity of sand and gravel is small and absorbs the same heat, the temperature will rise a lot, so the temperature difference between day and night in the desert is very large. The temperature difference between day and night on the coast is smaller than that in the desert, which is suitable for living. Since 20 10~20 13 years, the urban population is concentrated, the industry is developed, the traffic is congested, and the air pollution is serious. Most of the buildings in the city are stone and concrete. In the spatial distribution of temperature, the city is like a warm island, thus forming the urban heat island effect. In terms of alleviating the heat island effect, experts estimate that after the saplings of the green belt around the city of a medium-sized city grow into thick shade, the water conservation of the green belt throughout the year is equivalent to a medium-sized reservoir with a volume of1.14× 65438+100m3. Due to the large specific heat capacity of water, the high temperature in urban areas can be reduced by more than 65438 0℃ in summer, effectively alleviating the increasingly serious "heat island effect".

With the establishment of the reservoir, the water volume increases, but the specific heat capacity of water is large, and the temperature changes little with the same cold heating, so that the temperature in summer will not rise higher than in the past, and the temperature in winter will not fall lower than in the past, so that the temperature will remain relatively stable and the reservoir will become a huge "natural air conditioner". 1. Application of water cooling system

For a long time, people have been using water to cool hot machines. In the heat dissipation of computer CPU, the heat generated by CPU can be transferred to the heat sink through heat conduction, and then the heat dissipated into the air can be taken away by the fan. The specific heat capacity of water is much larger than that of air, so water can be used instead of air as a heat dissipation medium, and the water with increased internal energy can be taken away by a pump to form a water cooling system. In this way, after the heat generated by CPU is conducted into the water, the temperature of the water will not increase obviously, and the heat dissipation performance is better than that of the above-mentioned system directly using air and fans.

Cooling system of heat engine (such as automobile engine, power plant generator, etc.). ) It also uses water as cooling liquid, and it also takes advantage of the large specific heat capacity of water.

2. Application in agricultural production

Rice is a warm crop. In order to prevent frost, farmers generally use the method of "shallow irrigation", that is, pouring some water into the paddy field for the night, and then releasing the water from the paddy field when the sun rises the next day. According to the characteristics of large specific heat capacity of water, the temperature of seedlings does not change much at night, which plays the role of seedling insulation.

3. Hot water for heating

Radiators and hot water bags for heating in winter. The "heating" water in buildings in northern China takes water as the medium to bring the heat generated by fuel combustion to the house for heating.

4. Others

For example, in hot summer, the ancient royal family used tap water to flow down from the roof to prevent heatstroke and cool down; Hawaii is an island deep in the Pacific Ocean, where the climate is pleasant and it is a holy place for tourism and holiday. In addition to the charming scenery, there is another main reason that it is warm in winter and cool in summer.

For other information, please refer to the items of constant pressure specific heat capacity and constant volume specific heat capacity.