Compressed air purification system technical Q & a collection
1-1 what is air? What is wet air? Br
answer: the atmosphere around the earth is customarily called air. Air in nature is composed of a variety of gases (Oz, N:, C02 "... Etc.) Water vapor is one of them. Air containing a certain amount of water vapor is called wet air, and air without water vapor is called dry air. The air around us is wet air. At a certain altitude, the composition and proportion of dry air are basically stable, which has no special significance for the thermal performance of the whole wet air. Although the water vapor content in the wet air is not large, the change of the content has a great impact on the physical properties of the wet air. The amount of water vapor determines the dryness and humidity of the air. The working object of the cold dryer is wet air. Br
l-2 what is saturated air? Br
answer: under certain temperature and pressure, the content of water vapor in wet air (i.e. water vapor density) has a certain limit; When the amount of water vapor at a certain temperature reaches the maximum possible content, the wet air at this time is called saturated air. When the water vapor does not reach the maximum possible content, the moisture is called unsaturated air. Br
1-3 under what conditions does unsaturated air become saturated air? What is "condensation"? Br
answer: under the condition of constant water content, unsaturated air can be made into saturated air by reducing its temperature. When unsaturated air becomes saturated air, liquid water droplets will condense out of the wet air. This phenomenon is called "condensation". Br
l-4 what is atmospheric pressure? What is absolute pressure? What is gauge pressure? Br
answer: the pressure caused by a very thick atmosphere surrounding the earth's surface to the earth's surface or surface objects is called "atmospheric pressure", the symbol is B, and the pressure directly acting on the surface of the container or object is called "absolute pressure". The absolute pressure value takes the absolute vacuum as the starting point, and the symbol is PAbs; Br
the pressure measured by pressure gauge, vacuum gauge, U-tube and other instruments is called "gauge pressure" (also called relative pressure). The "gauge pressure" starts from atmospheric pressure and the symbol is PG. The relationship among br
is: pabs=b+pg: br
the legal unit of pressure is PA, and the larger unit is MPa 1mpa=106pa; Br
1 standard atmospheric pressure =0.1013mpa br
in the old unit system, the pressure is in kgf/cm2 (kg/cm2), 1kd/cm2=0.098mpa. what is temperature in BR
1-5? What are the common temperature units? Br
answer: temperature is the statistical average of the thermal motion of material molecules. Br
absolute temperature: the temperature starting from the lowest limit temperature when the gas molecule stops moving, which is recorded as t. Br
the unit is "Kelvin", and the unit symbol is K. Br
Celsius temperature: the temperature starting from the melting point of ice. The unit is "Celsius", and the unit symbol is OC. Br
in addition, British and American countries often use "Fahrenheit temperature", and the unit symbol is f. The conversion relationship between br
temperature units is: t (k) =t (℃) +273.16t (f):1.8t (℃) +32 br
1-6 what does the partial pressure of water vapor in wet air mean? Br
answer: wet air is a mixture of water vapor and dry air. In a certain volume of wet air, the amount of water vapor (by weight) is usually much less than that of dry air, but it occupies the same volume as dry air and has the same temperature. The pressure of wet air is the sum of the partial pressures of each component gas (i.e. dry air and wet air). The pressure of water vapor in wet air. It is called the partial pressure of water vapor and recorded as PSO. Its value reflects the content of water vapor in wet air. The higher the content of water vapor, the higher the partial pressure of water vapor. The partial pressure of water vapor in saturated air is called the saturated partial pressure of water vapor, pab Br
l-7 what is air humidity? How many kinds of humidity? Br
answer: the physical setting indicating the degree of air dryness and humidity is called "humidity". "Moisture content". "Br"
commonly used humidity expression methods are: absolute humidity "and" relative humidity ". Br"
under standard conditions, the weight of water vapor contained in wet air in lm3 volume is called "absolute humidity", and the unit is g/m3. Absolute humidity only indicates unit volume of wet air. The amount of water vapor contained cannot indicate the ability of the wet air to absorb water vapor, that is, it cannot indicate the humidity of the wet air. Absolutely 10. It is safe, reliable and helps to control humidity, that is, the density of water vapor in wet air. Br
the ratio of the actual amount of water vapor in wet air to the maximum possible amount of water vapor at the same temperature is called "relative humidity", and the relative humidity φ Between O and 100%. φ The smaller the value is, the drier the air is, and the stronger the water absorption capacity is. φ The higher the value, the wetter the air. The weaker the water absorption capacity. Br
1-8 what is the moisture content? How to calculate the moisture content? Br
answer: in wet air, the weight of ikg dry air containing water vapor is called "moisture content", which is commonly expressed in D, unit: g/kg dry air. The calculation formula of moisture content is: br
where: P - air pressure (PA), PS - partial pressure of water vapor (PA). PSB - partial pressure of saturated water vapor (PA), φ - relative humidity (%). Br
it can be seen from the above formula that the moisture content D is almost directly proportional to the partial pressure Ps of water vapor, and inversely proportional to the total air pressure P. D exactly reflects the amount of water vapor in the air. In a certain area, the atmospheric pressure is basically a constant value, so the air moisture content is only related to the partial pressure Ps of water vapor. Br
1-9 what does the density of water vapor in saturated air depend on? Br
answer: there is a limit to the content (density) of water vapor in the air. In the range of aerodynamic pressure (2MPa), it can be considered that the density of water vapor in saturated air only depends on the temperature and has nothing to do with the air pressure. The higher the temperature, the greater the density of saturated water vapor. For example, at 40 ℃, 1m3 air, regardless of its pressure of o.1mpa or 1.ompa, its saturated water vapor density is 51g "br"
l-10 how is the relative humidity and water content of air under pressure (i.e. compressed air) determined? Br
answer: I know from cluster question L-8. When the pressure P increases, the saturated moisture content in the air will decrease. Relative humidity of compressed air 7. Ultra high molecular weight polyethylene uhmwhpe φ’ And the actual water content PS' is determined by the following formula: where: PP 'is the absolute pressure of air before and after compression (PA) Br
pbpb'-- the partial pressure of saturated water vapor before and after compression and at their respective temperatures (P and) Br
φ Relative humidity of air before compression (%) φ’ - relative humidity of compressed air (%) 《 br 》
p'b 》 - saturated water vapor density corresponding to its temperature after compression (g/m3) 《 br 》
if 'p' =100%., the compressed air is in a saturated state. Saturated steam partial pressure of compressed air: br
this formula can be used to determine the corresponding conversion relationship between the "pressure dew point" of compressed air and the atmospheric dew point. Br
1 - what is the standard state of air? Br
answer: when the temperature is t=20 ℃, the absolute pressure is p=0.1mpa, and the relative humidity is' p=65%, the air state is called the standard state of air. Br
under standard conditions, the air density is 1.185kg/m3. (the exhaust capacity of air compressor, the processing capacity of dryer, filter and other post-treatment equipment are marked by the flow under the standard state of air, and the unit is Nm3/min, or anr can be added after m3/min). Br
the actual air state and the standard state are converted through the state equation. The equation of state has many forms. One of the forms is "br"
, where: P -- absolute pressure of gas (PA), V -- specific volume of gas (M '/kg), T -- temperature of gas (k) "br"
(unit symbol with 0 is the standard state parameter, and unit symbol with L is the actual state parameter) "br"
because the air quality before and after pressurization is unchanged. The volume of pressurized air can be calculated by using the equation of state: br
1-12 what is heat? Answer: heat is a form of energy. In physics, the "specific heat" is used to calculate the heat, that is, q=g C (T. t:), where q is the heat and G is the mass of the object. C - specific heat of the object.T1, T2 - initial and final temperature of the object. The unit of heat is J (joule). Heat is the energy transferred by temperature difference (T1-T2). Without temperature difference, there is no heat transfer. Br
according to the laws of thermodynamics, heat can be transferred spontaneously from the high-temperature end to the low-temperature end through convection, conduction, radiation and other forms. In the absence of external power consumption, heat can never be transferred in the opposite direction. Br
l-13 what is sensible heat? What is latent heat? Br
answer: during the heating or cooling process of an object, the heat that needs to be absorbed or released when the temperature increases or decreases without changing its original phase state is called "sensible heat". It can make people feel obvious changes in temperature and temperature, which can usually be measured with a thermometer. (if water is raised from 20 ℃ to 80 ℃, the absorbed heat is called sensible heat. Br>/p>
in the process of heat absorption or release, the phase state of the object changes (for example, gas turns into liquid...), but the temperature does not change. This absorbed or released heat is called "latent heat". "Latent heat" cannot be measured with a thermometer, nor can it be felt by the human body, but it can be calculated through experiments. Br
after the saturated air absorbs a certain amount of cold storage (i.e. gives off heat), part of the water vapor will turn into liquid water. At this time, the temperature of the saturated air does not drop, and the heat given off is "latent heat". Br
1-14 what is the enthalpy of air? How to calculate? Br
answer: the enthalpy of air refers to the total heat contained in the air, which is usually based on the unit mass of dry air. Enthalpy is indicated by symbol I, and the unit is K. the upper device of the moving beam has lower jaw J/kg dry air. The sum of enthalpy of LKG dry air and enthalpy of dkg water vapor, such as wet air baking value. Br
the calculation formula of wet air enthalpy is as follows: br
in rubber formula In terms of production process, self-help innovation has been realized
i=1.01t+ (2500+1.84t) d or i= (1.0l+1.84d) t+2500d (kJ/kg dry air) Br
where: T - air temperature ℃ "br"
d - moisture content of air g/kg dry air "br"
1.01 - average constant pressure specific heat of dry air kJ/(kg K) Br "
1.84 - average constant pressure specific heat of water vapor kJ J/(kg.k) Br
2500---0 ℃ latent heat of vaporization of water kJ/kg br
it can be seen from the above formula that: (1.ol+1.84d) t is the heat varying with temperature, i.e. "sensible heat"; While 2500d is the latent heat of vaporization of water at O ℃, which only changes with moisture content and has nothing to do with temperature, i.e. "latent heat". Br
the above formula is often used to calculate the heat load of the chiller dryer. Br
2.1 what is dew point? What does it have to do with? Br
answer: unsaturated air is under protection