Advanced equipment and corresponding equipment made extensive use of central air conditioning system has become one of the important symbol of modern construction techniques, modern architecture to create a comfortable and efficient working and living environment are an important and indispensable infrastructure. Its energy consumption, often accounting for more than 50% of the floor, the total energy consumption. Thus, central air-conditioning system is extremely important in modern, especially in modern intelligent building, central air-conditioning system is an essential part. Therefore, to study the significance of the central air-conditioning system energy consumption is especially important. To achieve the goal of the study on the energy consumption of air conditioning systems, how to create a good indoor environment under the premise of the use of energy, to achieve the minimum destruction of the external environment in order to achieve long-term sustainable development goals.
The impact of pollutants on the energy consumption of the ventilation system is reflected in the return air system and gathered a lot of dust and particulate matter generated on the inner wall of the pipe back to the wind, to reduce the performance of the damper and duct; while lowering send back to the wind speed and send back the amount of wind, increase the energy consumption of the fan.
Air path in the passage of time and an increase in use of the equipment life, its surface is attached to the large amount of dust (suspended particulate matter). This makes the side wall forming a boundary layer failure occurs, i.e. destroying the laminar flow state of the fluid in the duct. And the formation of a turbulent phenomenon, increased internal friction, so the wind hindered fan load increases, the unit capacity will reduce the useful life of equipment, increasing energy consumption.
1, the calculation principle
, The air flow in the duct due to the relative motion and fluid viscosity and fluid flow inertia and other factors, the formation of air-flow resistance in the duct, i.e. the frictional resistance and local resistance. The air in the duct flow process, it is necessary to overcome both the resistance and energy consumption. Duct air flow resistance;
2, the contamination before and after contrast
Now a fan coil air-conditioning system, new air handling system, for example, all duct galvanized steel (K = 0.15mm) production. Each outlet air volume 1080m3 / h, air conditioning processing box resistance 295Pa, calculated pipeline under different frictional drag coefficient required fan pressure head to select fan power resulting difference is the increase of energy consumption by fan pressure head .
3, the data analysis of the energy consumption caused by the pollution of the ventilation pipe
The above calculation is through pollution around the roughness of the inner wall of the central air-ventilation duct, it is determined the value of the coefficient of friction of different tube inner surface. Take the table in the calculation of the steel sheet in the contamination of the pipe before the maximum value of the coefficient of surface friction of 0.2, the take pollution thin steel sheet after the pipe inner surface friction coefficient, the minimum value is 0.75. Calculate the head and the blowing amount of the two kinds of the coefficient of friction of the tube under the required fan pressure. This difference can be considered to be contamination before and after the energy consumption by Fan Selection to identify the fan, the loss of motor power difference.
As can be seen by the above calculation, after contamination fan power rises almost doubled. That is in the pipeline pollution to maintain the original parts of the wind speed and wind pressure, the fan is equipped with the power of the motor almost doubled. Of energy consumption, however, the original power of the fan to the pipe blowing after contamination, according to Equation (1) shows that the air flow rate is proportional to the square of the inner friction and tube, i.e. to make the frictional resistance of the tube to maintain the original value is only so that the air flow rate decreased, and by calculating the flow rate decreased by about 50%. Fan a loss energy consumption of approximately 30% to 50%. The resulting room temperature up (down) time becomes longer, the unit time temperature up (down) the value reduced, making air conditioning host running time increased, the energy consumption is also a corresponding increase. Therefore, the energy consumption on the one hand from the loss of the fan, the main energy loss is caused to extend the run time of the host. Contamination of the ventilation system can be seen from the central air conditioning ducts have a great impact on the operation of the air conditioning, and the resulting energy loss can not be ignored. The purpose of energy saving can be achieved by regular cleaning of the ventilation system of the central air conditioning ducts.