What are the 6 psychrometric processes?
This is the series of articles that describes psychrometric chart and various psychrometric processes like sensible heating, sensible cooling, humidification, de-dumidification, evaporative cooling etc.
How is heating and dehumidifying represented in the psychrometric chart?
The dehumidification process maintains air at its dry bulb (DB) temperature constant while removing moisture. This process is represented on a psychrometric chart by drawing a straight vertical line that starts at the initial relative humidity value and extends downward to the ending relative humidity.
How do you read the humidity ratio on a psychrometric chart?
To read a psychometric chart, find the dry bulb temperature on the horizontal or X axis. Check the vertical or Y axis for the humidity ratio. The uppermost curved line on the chart shows the saturation curve when the relative humidity is 100 percent.
How do you read humidity levels?
Place two or three ice cubes into a glass, add water and stir. Wait three to four minutes. If moisture does not form on the outside of the glass, the air is too dry; you may need a humidifier. If water has condensed on the outside of the glass, the level of relative humidity is high.
What is cooling and dehumidification?
The process in which the air is cooled sensibly and at the same time the moisture is removed from it is called as cooling and dehumidification process. Cooling and dehumidification process is obtained when the air at the given dry bulb and dew point (DP) temperature is cooled below the dew point temperature.
What is psychrometric chart in HVAC?
Psychrometric chart is one of the chart that is commonly used in solving HVAC problems. The properties of air such as wet bulb temperature, dry bulb temperature, dew point temperature, relative humidity, humidity ratio, specific enthalphy and specific volume are shown on this chart.
What is humidification and dehumidification in AC?
What is the difference? Humidifiers add moisture to the air when it is too dry. Generally, people use humidifiers in the wintertime to combat the dryness of winter air. A dehumidifier takes moisture out of the air when it is too humid. Dehumidifiers are used during the spring and summer.
How do you calculate humidity ratio?
Humidity ratio is measured in units of pound-mass of water per pound-mass of dry air. By multiplying by 7000 [grains per pound-mass], this value may be expressed in grains of water per pound-mass of dry air.
What is the unit of humidity?
The specific humidity unit is the most reliable unit of measurement of humidity. This measures the weight of water vapor per unit weight of air and it is expressed as grams of water vapor per kilogram of air g.kg-1 is the specific humidity unit.
How do you read a hydrometer for humidity?
To read the result, look at the chart that is on the face of the device and read down starting from the wet bulb depression and then the temperature of the dry bulb. Get the spot where the numbers meet, and you will have the relative humidity of the area. Use percentage to express the final answer.
What is the cooling and dehumidification process on the psychrometric chart?
The cooling and dehumidification process is represented by a straight angular line on the psychrometric chart. The line starts from the given value of the DB temperature and extends downwards towards left.
How do you use a psychrometric chart to measure humidity?
For most applications the only information available is the dry bulb and relative humidity or dry bulb and wet bulb temperatures. The psychrometric chart is used to plot these two values by finding their intersection and then following the horizontal line to the right to determine the moisture content in grains per pound.
What is dehumidification?
What is Dehumidification? The process in which the moisture or water vapor or the humidity is removed from the air keeping its dry bulb (DB) temperature constant is called as the dehumidification process.
What happens to enthalpy of air during cooling and dehumidification process?
During the cooling and dehumidification process the dry bulb, wet bulb and the dew point temperature of air reduces. Similarly, the sensible heat and the latent heat of the air also reduce leading to overall reduction in the enthalpy of the air.