Rittal enclosures – classification of HVAC functions and system parameters

Heating, also known as heating, refers to the supply of heat to a building, insisting on a certain indoor temperature.

Ventilation – the process of feeding and removing air into a space by natural or mechanical means.

Air conditioning (referred to as air conditioning) is a technology that uses artificial methods to meet the requirements of production and life, improve labor and health conditions, and use artificial methods to make the air temperature, relative humidity, cleanliness and airflow speed of a room or confined space reach certain requirements.

HVAC includes heating, ventilation and air conditioning technologies, abbreviated as HVAC (Heating, Ventilating, Air Conditioning).

Material condition

Solid, liquid, gaseous

Vaporization of liquid state into gaseous process: endothermy;

The process of liquefaction of gaseous state to liquid state: exothermic;

The process of melting a solid state into a liquid state: endothermy;

The process of condensation of liquids into a solid state: exothermic;

Solid-state enhancement to gaseous process: endothermy;

gaseous condensation to solid state process: exothermic;

Note: Solid-liquid conversion will be used in ice storage systems; Changing the situation will store a large amount of energy: latent heat.

Specific Heat: The amount of heat required to raise the temperature of a substance by 1°C for 1 gram.

Sensible heat: When an object absorbs heat (or exothermic) only increases (or decreases) the thermal kinetic energy of the molecules of the object, that is, it only increases (or decreases) the temperature of the object, and does not change the shape of the substance, then the heat it absorbs (or emits out).

Latent heat: When an object absorbs heat (or exothermic) only increases (or decreases) the heat potential of the molecules of the object, causing the condition of the object to change, while its temperature does not change, then the heat it absorbs (or emits) is called latent heat.

Air conditioning system parameters

Temperature is used to indicate how cold and hot a substance is.

It is divided into dry bulb temperature: dry bulb temperature is the temperature measured by the thermometer in the general air, that is, the air temperature that we often say in our general weather forecast.

Wet bulb temperature: refers to the air temperature when the water vapor in the air reaches full under the equal enthalpy value air condition, and the dry bulb temperature at the corresponding point is the dry bulb temperature at the corresponding point from the air condition point to the 100% relative humidity line along the isenthalpy line on the air enthalpy map.

Wrap the temperature-sensing part of the general thermometer with wet gauze, soak the lower end of the gauze in water, insist that the air humidity of the temperature-sensing part reaches fullness, and insist on a certain air circulation around the gauze, so that the surrounding air is close to the enthalpy. When the indication reaches stability, the thermometer displays a reading that approximates the wet-bulb temperature.

The enthalpy is a condition function in thermodynamics that indicates the energy of a material system, and is often indicated by the symbol H. Numerically equal to the product of the internal energy U plus pressure p and volume V, i.e., H=U+pV. The change in enthalpy is a measure of the amount of heat absorbed by the system in an isobaric reversible process, that is, the amount of energy carried by the substance.

Enthalpy of moist air: It is the sum of the enthalpy of dry air and the enthalpy of the corresponding water vapor, and dry air is also commonly used as the accounting basis. General rule: The enthalpy of dry air and liquid water is the sum of 0°C, and the corresponding enthalpy of water vapor is zero.

Dew point: The moist air is cooled under the condition that the total pressure and humidity remain constant, and the temperature when the moist air reaches the full level is the dew point. If the temperature of moist air drops below the dew point, the water vapor containing more than the full part will condense in the form of liquid water.

The boundary of humidity: also known as moisture content, is the quality of water vapor carried by a unit mass of dry air. Unit: g/kg

Positive humidity: calculated by the mass of water vapor contained in a unit volume of air, unit: kg/m3

Relative humidity: is the ratio of the partial pressure of water vapor in moist air to the partial pressure of water vapor in full air at the same temperature and total pressure. （％RH）

Relative humidity is a sign of how full the moist air is. The lower the relative humidity, the farther away from fullness, and the greater the ability of that moist air to contain moisture. When the relative humidity is 100%, the moisture in the humid air has reached full, and the moist air can no longer contain the moisture, so it cannot be used as a drying medium. Affirmatively the relative humidity of dry air is zero.

Rittal enclosures – classification of HVAC functions and system parameters

Rittal enclosures – classification of HVAC functions and system parameters

Sections viewed

Contact

working hours