Why can water cool below room temperature?

Compared to air, water is a good conductor of heat. The body is exposed to air, and heat** is the body's production of heat and radiation, including sunlight. In this case, even if the air temperature is lower than the body temperature, it will still feel hot if the heat transfer speed between the air and the air is not enough.

When in contact with water, even if there is not much difference between water temperature and temperature, due to the rapid heat conduction, the body has obvious heat release - in the eyes of the brain, if it is in the air, this often happens when it is colder. If the object of the description is a relatively large body of water, then the large specific heat capacity of the water should be investigated. To what extent is the specific heat capacity of water?

This can be seen in the reversal of the seasons on land and sea. Therefore, when the air temperature rises, the water temperature can not change much for a long time. At this time, the water temperature is really cooler than the air temperature.

Will the water temperature be higher than the air temperature? Of course, we will, but due to reason 1, as long as the water temperature is less than 36 degrees Celsius, we may not notice it. A glass of water, a basin of water, a pool of water, a pool of water, they are not closed systems, so the same temperature as the heat source does not guarantee equilibrium.

For example, all kinds of strange things on the surface of the liquid represented by evaporation, who can figure out what happened to the unconscionable energy exchange ......These effects certainly have an effect on the temperature in the sense of equilibrium, but I don't know exactly how and by what order of magnitude evaporative endothermy, although I want to say so, but in fact for a large amount of water (such as a cup, a basin), this effect is far from obvious enough to cause the overall temperature to drop. After the water has been left at room temperature for a long time, the temperature should be measured with a thermometer and the temperature should be almost the same as room temperature. The temperature you feel with your hands is different because the temperature of your hands is higher than room temperature, and water conducts heat quickly, so it appears cold.

For water with a large surface area and a small volume, such as a wet cotton ball, evaporation will cause the temperature to be lower than room temperature, which is also the principle of wet and dry thermometers. <>

The temperature of the water is higher than that of the cup, so the heat is transferred to the cup. The specific heat capacity of the cup should be smaller than that of water (depending on the material), so the temperature of the cup rises. Because the cup is already at room temperature and there is heat transfer, it will definitely rise to a temperature higher than the air temperature.

With the temperature difference, the heat transfer between the cup and the air is generated, and at the same time, the heat transfer between water and air occurs in the open part of the cup. In the mixed method, the glass of water is cooled directly to a temperature that is not much different from the room temperature, and then the heat transfer process is repeated in the above section of the room temperature, which refers to the room temperature. For ordinary people, the change in room temperature does not affect them very much, and there is no mandatory requirement.

However, for some special industries (such as the pharmaceutical industry), there are strict regulations on room temperature, and the room temperature must be regulated in accordance with industry guidelines. <>

The room temperature is the same as at zero degrees below zero, because the ice directly produces sublimation, and the rate of sublimation heat absorption is less than the speed of ice heat conduction, resulting in the same temperature as the temperature of room temperature and water (ice). When the room temperature is above zero, the water evaporation not only absorbs the indoor heat, but also absorbs the heat in the water, and the speed of absorbing the heat in the water is greater than (slightly greater) than the thermal conductivity rate of the water, causing the water temperature to be lower than the room temperature. In addition, the higher the room temperature, the faster the water evaporates, and the faster the heat absorption rate in the water is faster than the heat conduction rate.

That is, the higher the room temperature, the lower the temperature of the water is than the room temperature. So the temperature of the room and the temperature of the water are not the same. Concentrated sulfuric acid dissolved in water is an exothermic reaction, and the temperature of the aqueous solution decreases after the reaction, but the concentrated sulfuric acid and water in the initial state are at room temperature, so even if the temperature of the solution drops, it will not be lower than room temperature!

The water temperature should be around 30, < 36 is the best.

If alcohol is to be added, the water temperature should be slightly higher, as the temperature slip will be slightly reduced after the addition of alcohol. Physical cooling is to warm water with cold water: usually the method of about 32-34 warm water is used for physical cooling of the nuclear grinding temperature, instead of using hot water. Closed wax.

Thermometer Introduction:

A thermometer is a tool that can accurately judge and measure temperature, and is divided into a pointer thermometer and a digital thermometer. Depending on the purpose of use, a variety of thermometers have been designed and manufactured.

On October 16, 2020, the State Food and Drug Administration issued the Notice of the General Department of the State Food and Drug Administration on Matters Related to the Implementation of the Minamata Convention on Mercury. The "Notice" clearly requires that from January 1, 2026, China will completely ban the production of mercury-containing thermometers and mercury-containing blood pressure monitor products.

The first thermometer was invented in 1593 by the Italian scientist Galileo Galilei (1564 1642). His first thermometer was a glass tube with an open end and a walnut-sized glass bubble at the other. To use, heat the glass bubble and insert the glass tube into the water.

As the temperature changes, the water surface in the glass tube moves up and down, and the temperature change and temperature can be determined according to the amount of movement. The thermometer has the effect of thermal expansion and contraction, so this kind of thermometer is greatly affected by environmental factors such as external atmospheric pressure, so the measurement error is large.

The above content reference: Encyclopedia - Thermometer.

Summary. Hello, dear, I'm honored to answer for you! <>

The medium temperature water of the HVAC can be reduced by closing the valve at the outlet end. Or open a small window. Heating is to rely on the hot water in the radiator to heat the surrounding air temperature, and then use the principle of hot air with light gravity to produce natural convection of indoor air to achieve the purpose of warming the room.

When the hot water in the radiator is overheated, the temperature of the closed room will be too high, making it hot. At this time, the outlet valve can be closed to reduce the hot water flow rate, which can reduce the amount of hot water, and also reduce the amount of heat exchange between hot water and air, so that the indoor temperature will not be too high. Or open some small windows, just to maintain the indoor air clean, which is beneficial to the human body.

How to lower the temperature of medium water.

How can the medium-temperature water of the HVAC be lowered.

Hello, dear, I'm honored to answer for you! <>

The medium temperature water of the HVAC can be reduced by closing the valve at the outlet end. Or open a small window. Heating is to rely on the hot water in the radiator to heat the surrounding air temperature vertical bridge, and then use the principle of light gravity of hot air to make the indoor air produce natural convection, to achieve the purpose of warming the room.

When the hot water in the radiator is overheated, the temperature of the closed room will be too high, making it hot. At this time, the outlet valve can be closed to reduce the hot water flow rate, which can reduce the amount of hot water, and also reduce the amount of heat exchange between hot water and air, so that the indoor temperature will not be too high. Or open some small windows, just to maintain the cleanliness of indoor air, which is beneficial to the human body.

The treatment method of reducing the warm water of the source of HVAC is that the temperature of the purification room will also increase, on the contrary, the electric control valve will be gradually opened, and the low-temperature chilled water entering the secondary medium-temperature water circulation system will gradually increase, so that the water temperature in the pipeline of the secondary medium-temperature water circulation loop will gradually decrease, and the temperature of the purification room will also be reduced.

If the water is sealed and the original temperature is higher than the ambient temperature, the water will release heat into the environment until it is in thermal equilibrium;

If the water is sealed and the original temperature is lower than the ambient temperature, the water will absorb heat from the environment until it reaches thermal equilibrium;

If the water surface is open, the water will evaporate, and evaporation is an endothermic process that will take heat away from the water, causing the water temperature to decrease; If the water temperature drops below the ambient temperature, the water will in turn absorb heat from the environment; Finally, the rate of heat consumption of water evaporation is equal to the rate of heat absorption from the environment, reaching an equilibrium state, and the water temperature is lower than the ambient temperature; The difference between the water temperature and the ambient temperature depends on the rate at which the water evaporates and the rate at which heat is absorbed from the environment.

When the water temperature is higher than the ambient stability, the water transfers heat to the space until it is consistent with the ambient temperature.

Evaporation is an endothermic process.

will take heat away from the water.

As long as it is not ideal adiabatic isolation, heat is always transferred spontaneously from a hot object (or place) to a low temperature object (or place), and this transfer does not stop until the temperature of the two objects (or places) is the same, and the state at this time is called thermal equilibrium.

When an object loses heat, its temperature decreases; When an object gains heat, its temperature increases.

If the initial temperature of the indoor water is higher than the room temperature, the heat in the water will gradually transfer to the environment, and the temperature of the water will slowly decrease due to the loss of heat; Strictly speaking, in this process, the temperature of the indoor environment will increase due to the heat gained, but the general indoor environment is more extensive, the heat capacity is larger, and there is also heat exchange between indoor and outdoor, so the change in room temperature is usually small and is often ignored.

As the temperature of the water approaches the room temperature, the rate of heat transfer also gradually decreases, and after a sufficiently long (theoretically infinite) period of time, the water reaches thermal equilibrium with the indoor environment at the same temperature.

Thermal equilibrium A high temperature object transfers heat to a low temperature object

1. If the temperature is not too low, you can use a fan to blow continuously to evaporate part of the water and reduce the remaining temperature.

2. Put the water in a sealed container, connect the container to the sobbing gas equipment, and continuously pump the air, which should be able to freeze the water.

The principle is that evaporation takes away heat.

In case of high water temperature or even boiling of the pot:

1. Do not try to continue driving, so as not to cause major accidents.

2. Do not try to open the lid of the water tank, otherwise it is very likely that hot liquid will spray out and cause scalding.

3. Do not pour cold water on the engine block and cylinder head, which is likely to cause the cylinder block to burst due to quenching.

Step 2: After a period of time, check for water leaks under the car.

Step 3: Wait until the water thermometer pointer drops to the appropriate temperature position, then turn off the engine.

Step 4: Wrap the water tank cover with a wet towel, slowly open the first switch (about 1 4 turns), beam and wait for the water vapor pressure to be released, and then completely open the water tank cover, check the water quantity and quality in the water tank, and whether the fan belt is abnormal. If the amount of water is insufficient, you should slowly add water to the vicinity of the highest marking.

Car Superman Maintenance Platform Warm Tips: If the water tank is leaking or the fan belt is loose or damaged, you can call the towing company and wait for the tow truck rescue. If necessary, you can also wait for the engine to cool down completely, and then drive the car to the service shop for maintenance in a low-speed driving mode.

Remember, you can't drive at normal speed, as there is a high risk of permanent damage to the engine.

Car Superman offers professional daily maintenance methods.

Generally speaking, the antifreeze should be replaced after driving 20,000 kilometers or a year; When antifreeze is not available, never add tap water.

Rust and fouling of the engine water tank are the most common problems. Rust and scale can limit the flow of antifreeze in the cooling system, reduce heat dissipation, and cause engine overheating or even engine damage. Antifreeze oxidation can also form acids that corrode the metal parts of the tank, causing the tank to break and leak.

The solution to the failure of the water tank is mainly in the routine inspection on weekdays, should often check whether the water tank has water leakage or rust, to clean on time, replace or add antifreeze to improve the boiling point, prolong the service life. Generally speaking, the antifreeze should be replaced after driving 20,000 kilometers or a year; This can improve the boiling point, prevent scale, rust and improve the heat dissipation effect, so that the water pump has a lubricating effect, and avoid and eliminate the engine damage caused by instantaneous high temperature caused by bubbles.