Building Services

Building Services

Building Services

Question No 1:

Dry bulb temperature

Dry bulb temperature is usually regarded as the temperature of the temperature, it is true thermodynamic temperature. The dry bulb temperature in the weather does not show that the right humidity values. In the building, when designing a climate when a building should focus consider it. Human comfort and building energy efficiency are considered the most important climate variables.

Dry-bulb temperature is the contact surface of the sphere of actual air temperature. The dry bulb temperature can be observed to be difficult to use short text gives the exact definition of rigor. Dry bulb temperature is calibrated as a means of air relative humidity, and its meaning is a state of the air, with the thermometer the dry bulb contacts occur adiabatic heat and moisture exchange, to reach the saturation temperature. The greater the difference between the ambient air saturated, dry bulb thermometer evaporation occurs strongly. Dry-bulb temperature is the contact surface of the sphere of actual air temperature, the sphere after evaporation temperature of the heat away, the evaporation of water and air humidity of the air humidity, the greater evaporation The smaller, less heat away, the smaller the difference between wet and dry bulb temperature; air humidity, the smaller the greater the amount of water evaporated, the greater the heat away, wet and dry bulb temperature , the greater, so the temperature variation can be observed for the ball to reflect the current air humidity conditions (Ortiz, 2011). Applied dry - bulb thermometer is measuring relative humidity or moisture content than the easy way. The dry bulb thermometer is an ordinary thermometer, while the end of the dry bulb thermometer head was submerged wick package. As the air flows through the air dry bulb temperature indication T, also known as dry-bulb temperature, and bulb wick reflect the temperature of the water, the temperature value is known as the Dry bulb temperature, which means a t w. If the air is not saturated, the water in the wick evaporates leaving air temperature will decrease. The temperature difference between air and water absorbent core causes the air to heat the water, thereby preventing the water temperature continues to drop. Thus, in equilibrium, the wet-bulb temperature t w is always lower than the dry bulb temperature, but lower than the air dew point temperature t d is high. Dry-bulb temperature t w is greatly dependent over the heat transfer process, and the evaporation rate and mainly by the air relative humidity. If the air is saturated, then the evaporation process does not occur, and thus the heat transfer process does not occur, the dry-bulb temperature is the same. The smaller the relative humidity of air, the dry bulb temperature is increased. Airflow velocity on the evaporation and heat transfer process has an impact, and thus dry bulb temperature values also have some impact through it, but the experiment showed that when the flow velocity in 2 ~ 10m / s range, the ...