What does refrigerator cooling capacity mean? What is the principle?
I often hear people ask, what is the refrigeration principle of refrigerators? The temperature in the refrigerator has dropped. Where has the heat in the refrigerator gone? Isn’t this a violation of the law of conservation of energy? Where did the electricity consumed by the refrigerator go? Will it be refrigerated directly like it heats up quickly? Faced with so many questions, I have summarized and summarized the answers as follows.
Where did the heat absorbed by the refrigerator go?
The heat in the refrigerator and freezer compartment is dissipated into the room through the outer wall of the refrigerator. This is a process of energy transfer and does not violate energy conservation. At the same time, the heat dissipated into the room also includes the heat generated when the internal equipment in the refrigerator is working.
Therefore, some people open the refrigerator door and want to cool the room in this way, which is not feasible: the heat dissipation capacity of the refrigerator = the cooling capacity of the refrigerator + the heating capacity of the refrigerator. So the more you open the refrigerator door, the higher the indoor temperature.
Where did the electricity consumed by the refrigerator go?
In the refrigerator system, electrical energy does not participate in refrigeration, it only provides power to the refrigerant-if the refrigerator wants to cool, the refrigerant must constantly move in the pipes, which we will talk about later.
For example, the electricity here is like gasoline in a car. It is the engine that actually moves the car forward, but the gasoline provides energy for the engine.
Principles of refrigerator refrigeration
We think of the refrigerator as two parts: inside the refrigerator and outside the refrigerator. The main function of the device in the refrigerator is to absorb heat, which is refrigeration. Its main device is the evaporator. The external device of the refrigerator is to dissipate heat and provide power. Its main devices are compressor, condenser and capillary tubes.
Here we focus on the refrigeration principle of refrigerant. It does not achieve heat absorption by lowering its own temperature as we imagine. Instead, a physical phenomenon-liquid boiling absorbs heat. Why can liquid refrigerant in the refrigerator boil? This is another physics knowledge-the lower the pressure, the lower the boiling point.
Refrigerant is gaseous at room temperature. In other words-when liquid refrigerant is placed at room temperature, it will boil. The reason why refrigerant can turn into liquid in the refrigerator is because the refrigerator provides a high-pressure environment for the refrigerant. Let’s first take a look at the refrigeration schematic of the refrigerator
In this figure, the direction of the arrow represents the direction of movement of the refrigerant. Red means that the refrigerant is at high temperature and high pressure (liquid state), yellow means that the refrigerant is at normal temperature and high pressure (liquid state), green means that the refrigerant is at normal temperature and pressure (boiling state), and blue arrows mean that the refrigerant is at normal temperature and pressure (gaseous state)-to correct here, from the green arrow to the blue arrow, the period is the state in which the refrigerant absorbs heat, that is, the process of rapid change from liquid refrigerant at normal temperature and pressure to liquid refrigerant at normal temperature and pressure through boiling. This is a gradual transition process. The color of the arrows in the picture becomes too abrupt. The entire gradual transition process occurs in the evaporator.
The following is a summary of all the contents written in this article, starting from the perspective of the refrigerant: the compressor starts (consumes electricity and generates heat) to provide power for the movement of the refrigerant.
The gaseous refrigerant passes through the condenser and encounters the capillary tube, but the tubes of the capillary tube are relatively thin, causing a large amount of refrigerant to crowd in the condenser. One pushes towards the capillary tube (compressor) and the other blocks it (capillary tube). More and more refrigerant stays in the condenser, and the pressure becomes larger and larger.
After the pressure increases, the gaseous refrigerant begins to liquefy, and the liquefaction process is accompanied by heat absorption, so the refrigerant staying in the first half of the condenser (near the compressor) is a liquid state of high temperature and high pressure. The refrigerant slowly cools down in the condenser until it drops to room temperature and begins to slowly line up through the capillaries.
The pipes of the evaporator are thicker, and the pressure of the refrigerant passing through the capillary tube suddenly drops, so the liquid refrigerant begins to boil and vaporize (with heat absorption). Until the refrigerant completely passes through the evaporator, it also completely becomes a gaseous state at normal temperature and pressure. The gaseous refrigerant passes through the compressor again and continues a new cycle.