Improve the energy efficiency of HVAC from the details
As the saying goes, the details determine success or failure. The operating efficiency and energy saving effect of the HVAC system depend to a large extent on its detailed design. According to the reporter's understanding, in the southern part of China, for every 1 °C reduction in summer interior design temperature or 1 °C increase in winter design temperature, its engineering investment will increase by 6% and energy consumption will increase by 8%. The data clearly shows that a proper increase in summer and a reduction in indoor air temperature in winter will have significant energy savings.
Many HVAC designers agree with the new airflow regulations in the new code. The current "Code for Design of Heating, Ventilation and Air Conditioning" clearly stipulates the minimum fresh air volume, and requires the building to meet the relevant national health standards. They believe that in the context of the current lack of standard air conditioning cleaning, it is necessary to increase the amount of fresh air. However, they have reservations about the indoor design temperature requirements. There is a very vivid saying in the HVAC industry: "If energy conservation is like a tree, many branches can be used as ideas. Then, the opinions of the owners are more like that root. Their attitude will become the decision of HVAC professional and even The fundamental factor of building energy efficiency.” In the construction sector, the opinions of the builders are very important. In addition, in order to increase the fresh air volume or enhance the ability of the fan coil to handle the indoor return air, the fresh air outlet of the fan coil plus fresh air should be placed separately or next to the coil outlet, and should not be placed in the coil return air inlet. .
Studies have shown that increasing the amount of fresh air can solve indoor air quality problems to a certain extent, but increases system energy consumption. The fresh air setting must be determined according to the specifications, because the fresh air volume plays a very important role in energy consumption and human health. If the density of personnel is large, the supply of fresh air is very uneconomical based on the density of personnel. China's buildings use fresh air demand control (detecting indoor carbon dioxide concentration). It is worth noting that the fresh air volume changes and the exhaust air volume changes accordingly, otherwise the negative pressure will be counterproductive.
According to the reporter's understanding, for a plurality of air-conditioning zones to use an air-conditioning air system, the load changes in each zone are large, the low-load operation time is long, and the indoor temperature needs to be adjusted separately. When economic conditions permit, it is recommended to use the full air variable air volume. Adjust the system. Attention should be paid to three points in design: First, the fan speed should be used to change the system air volume, but the fixed speed fan can not be used to change the system resistance adjustment. Second, measures to ensure the minimum fresh air volume should be taken to avoid the decrease of air supply volume. The fresh air volume does not meet the hygienic requirements; thirdly, when adjusting the air volume at the end air supply, it is recommended to use a series fan-driven end device to ensure the air distribution in the room. Similar to the case where the heat transfer amount of the roof is large, the heat generated in the ceiling is large, and the ceiling space is large (the height from the ceiling to the bottom of the floor exceeds 1 m), if the return air is used inside the ceiling, the air conditioning area will increase and the air conditioner will be increased. Problems such as rising energy consumption are very unfavorable for energy conservation. Therefore, when the top of the building or the upper part of the ceiling has a large amount of heat and the ceiling space is high, it is not reasonable to return directly from the ceiling. For areas with large room area or large space, large number of people or where temperature control is necessary, the air conditioning system should adopt an all-air air conditioning system instead of a fan coil system to facilitate centralized processing, adjustment, and play a favorable factor. To make up for the problems that have arisen before.
When the height of the building space is greater than or equal to 10 meters and the volume is greater than 10,000 cubic meters, a layered air conditioning system should be adopted. Compared with the whole room air conditioning system, the stratified air conditioning system can save about 30% in summer, but the energy saving effect in winter is not obvious. Usually designed, the air flow in summer is sent to the side of the nozzle, the lower return air, the upper part of the high space is exhausted; in winter, the floor radiation or floor air heating system is generally installed on the ground floor, and the upper superheated air can also be sent to the room through the air duct. Lower part.
Introduction of three air supply methods in data center