Applications of enthalpy?

Enthalpy: The enthalpy in air refers to the total heat contained in the air, and it is usually expressed per unit mass of dry air, known as specific enthalpy. In engineering, it is abbreviated as enthalpy; it refers to the sum of the enthalpy of one kilogram of dry air and the enthalpy of the water vapor associated with it. In engineering, we can determine whether air gains or loses heat based on the change in specific enthalpy of a certain mass of air during the processing stage. An increase in the specific enthalpy of air indicates that heat has been added to the air; a decrease in its specific enthalpy indicates that heat has been lost from the air. From another perspective, enthalpy is a combination of temperature and humidity; it is an energy unit that represents a scale of the combined effect of temperature and humidity in a given amount of air. In the air conditioning industry, since the main tasks are to heat, cool, humidify, or dehumidify the air, comparing only temperature is insufficient and even incorrect. Cooling is required to lower temperature, and cooling is also needed for dehumidification; therefore, a comprehensive calculation is necessary. For example, during the transitional seasons, the opening and closing of fresh air valves is controlled in such a way that when the enthalpy value of the outdoor air is lower than that of the indoor air, it is possible to introduce outdoor air directly without the need for cooling.