What Is Heat Recovery Ventilation?

Heat recovery is to recover the waste heat (cold) or waste heat (cold) inside and outside the building, and use the recovered heat (cold) as a heat source for heating (cold) or other heating equipment. ("Building Energy Efficiency Technology")

Energy consumption in the construction industry includes energy consumption in the production of building materials, construction, and daily operation of the building. The daily energy consumption of a building is also called the energy consumption of people's livelihood, also called the energy consumption of a building. It includes energy consumption for heating, ventilation, air conditioning, hot water supply, lighting, elevators, cooking, etc. The energy consumption of urban buildings in China accounts for 22% to 24% of the national energy consumption, while developed countries account for about 1/3. ^[1]

The heat emitted by the unit through the condenser is usually discharged to the surrounding environment by a cooling tower or a cooling fan. It is a huge waste for places that need heat, such as hotels, factories, hospitals, etc., and it also brings a certain amount of waste heat to the surrounding environment. Pollution.

The heat recovery technology is to use a certain method to recover and reuse a large amount of waste heat discharged to the outside during the operation of the chiller as the user's final heat source or primary heat source.

The high-temperature and high-pressure gaseous refrigerant discharged from the compressor first enters the heat recovery device, releases heat to heat domestic water (or other gas-liquid substances), and then passes through the condenser and expansion valve.

According to the amount of heat recovered by the heat recovery device, the heat recovery can be divided into partial heat recovery and total heat recovery. Among them, part of the heat recovery can only recover part of the heat emitted by the chiller, and the full heat recovery basically recovers all the heat discharged into the environment by the system.

According to the different places of use and the specific needs of the user terminal, the heat recovery device can take a variety of different forms, such as shell and tube, plate, finned tube, sleeve and so on.

Fresh air energy consumption accounts for a large proportion in air conditioning ventilation systems. For example, office buildings can account for approximately 17% to 23% of total air conditioning energy consumption. In order to ensure the indoor air quality of the room, it is not possible to save energy by reducing the amount of fresh air, and it may also be necessary to increase the supply of fresh air. When fresh air enters the building, an equal amount of indoor air must be discharged. These exhausts contain heat (winter) or cold (summer) relative to the fresh air. In many buildings, the exhaust air is organized, rather than squeezed out from gaps such as doors and windows. In this way, it is possible to recover heat or cold from the exhaust air to reduce the energy consumption of the fresh air. The exhaust air heat recovery device utilizes an air-air heat exchanger to recover cold (heat) energy in the exhaust air to pre-treat the fresh air. The air-to-air heat exchanger is the core of the exhaust heat recovery device. According to different types of heat exchangers, the common exhaust heat recovery methods include rotary heat recovery, plate-fin heat recovery, heat pipe heat recovery, and coil. Heat recovery, etc. ^[2]

There are no exterior walls and windows in the inner area of the building.

Modern buildings are equipped with air conditioning systems, and usually a large amount of condensed heat is discharged to the surrounding environment, which not only wastes heat, but also generates thermal pollution to the surrounding environment. The relatively easy use of condensing heat is used as pre-heating of domestic hot water or heating of swimming pool water. Even existing air-conditioning systems can be easily retrofitted. ^[1]

The drainage of the building contains a large amount of heat, which can be extracted for domestic hot water supply or heating using heat pump technology. There have been many actual projects of sewage source heat pump air-conditioning systems in China, which have achieved good energy-saving effects. Several water source heat pump systems in Harbin and Daqing directly take sewage from urban drainage pipes, and their heating performance coefficient is 3.75 ~ 4.0. ^[1]