Medical building figure 1 Figure 2 at present, the heat and humidity treatment process of the purified air conditioning system has the following forms: (1) the fresh air is initially cooled and dehumidified by the cooling coil of the pretreatment unit, and then further cooled and dehumidified by the direct expansion evaporator to achieve deep dehumidification.
One supply and one return two water pipes are used to connect the cold source to the unit, and the air conditioning water system is a two pipe system.
Heat and humidity treatment process of air conditioner (2) after centralized cooling treatment, the fresh air is mixed with the indoor return air, treated to the dew point of the machine through the surface cooler of the circulating unit, and then heated to the air supply state point and sent indoors.
This paper analyzes the different heat and moisture treatment processes of purified air conditioning system and the corresponding forms of air conditioning system.
Such equipment can replace the boiler + chiller mode, realize the multi-functional cold and heat source integrated machine, and solve the requirements of refrigeration, dehumidification and reheating of purified air conditioner, so as to achieve the purpose of constant temperature and humidity control.
Paragraph 5 of article 8.3.1 of technical code for building of hospital clean operation Department gb50333 – 2013 stipulates the reheating method as follows: “when reheating is required in the air treatment process, electric heating devices should not be used completely, and waste heat and waste heat can be used as the reheat source of air supply”.
After cooling and dehumidification, it is heated to the air supply point and then sent indoors.
(2) Purified air conditioning circulating unit (two pipe) (Figure 5) Figure 5 this type of air conditioning circulating unit is equipped with a group of coils, cooling coils in summer and heating coils in winter, which can only be used for single refrigeration or single heating, and the air conditioning water system is a two pipe system.
It is composed of compressor, condenser, evaporator, convertible heat exchanger, etc.
The working principle of four tube multifunctional cold and hot water unit is energy recovery and effective utilization.
Fixing Socket Waved End Nail Plate
Paragraph 4 of article 4.2.15 of design standard for energy efficiency of public buildings (gb50189 – 2015) for purified air conditioning cold and heat sources stipulates the selection of air source heat pump units as follows: “for buildings with simultaneous cooling and heating, heat recovery heat pump units should be selected”.
This heat and humidity treatment method needs to be equipped with fresh air pretreatment unit, which is mainly used in areas with large number of purification air conditioning units and large area of air conditioning room, such as clean operation Department.
The reheating process of air is realized by the electric heating device set behind the surface cooling section.
(3) After the fresh air is mixed with the indoor return air, it is treated to the dew point of the machine through the surface cooler of the circulating unit.
Hospital purification air conditioning system has more strict requirements for controlling indoor temperature and humidity than ordinary comfort air conditioning system.
The air conditioning water system is a four pipe system, which can realize single refrigeration or single heating and simultaneous refrigeration and heating.
The relative humidity of the medical room is mainly related to the survival time of bacteria in the air.
Therefore, controlling the relative humidity is an important task of purifying the air conditioning system in the hospital.
According to the provisions of the above specifications, the purified air conditioning unit shall give priority to hot water reheat as the reheat mode, so the purified air conditioning water system shall give priority to the four pipe system.
When the four pipe system is adopted, it is necessary to provide cold and hot water for the air conditioning unit for cooling and reheating in summer.
The working principle of the four pipe water system with two independent circuits is shown in the figure.
Through the analysis of the configuration of the above air conditioning terminal, the reheat heat source of the purified air conditioning unit includes electric reheat and hot water reheat.
(this heat and moisture treatment method is mainly used in areas such as ICU, central supply room, vein configuration center, etc., where the number of purification air conditioning units is small and the area of air conditioning room is small.) Figure 3 for the above three forms of heat and moisture treatment, the following configurations are generally adopted at the end of the air conditioner.
This heat and humidity treatment method needs to be equipped with fresh air pretreatment unit, which is mainly used in areas with large number of purification air conditioning units and large area of air conditioning room, such as clean operation Department.
According to the provisions of the above articles, it is recommended to use a four tube multi-functional cold and hot water unit that can use the condensation heat recovery technology to provide cold and hot water at the same time as its cold and heat source.
The greater the relative humidity is, the longer the survival time of bacteria is.
After reheating, it is sent to the circulating unit and mixed with the return air, and then enters the cold water coil of the circulating unit for equal humidity cooling, After being treated to the air supply temperature, it is sent indoors.
In addition, the hot water reheating has strong adaptability to the change of indoor load, flexible adjustment and can meet different temperature and humidity requirements, It can accurately control the air conditioning system with different cooling and heating loads.
Article 4.2.2 of design standard for energy efficiency of public buildings (gb50189-2015) clearly limits the use of electricity as heating device.
When the combined cooling and heating operation of the unit, its refrigeration energy efficiency ratio can reach 4.0, while the heat energy efficiency ratio can reach 5.0 and the combined cooling and heating energy efficiency ratio can reach 9.0, which can greatly save the operation cost of users in the later stage..
The objects controlled by the purification air conditioning system of medical buildings are indoor temperature, humidity, air flow form, wind speed, noise, cleanliness, etc., so as to ensure the demand of medical staff and patients for indoor air quality.
Since the cold and hot water pipes of the four pipe system are separated, the air can be cooled by the surface cooling section and then directly reheated through the heating section in summer, without the need for electric heating device.
(3) Purification air conditioning circulating unit (four pipe) (Figure 6) Figure 6 this type of air conditioning circulating unit is equipped with a group of cold and heat treatment coils, and a group of water supply and return pipes are respectively used to connect with cold source and heat source.
At the same time, as a backup scheme for the first heat and humidity treatment process, when the deep dehumidification module fails, the heat and humidity treatment process is adopted.
The conventional reheating heat sources include hot water boiler and heat pump unit.
(1) Fresh air pretreatment unit (equipped with deep dehumidification section) (Figure 4) Figure 4 this type of fresh air unit is equipped with a group of coils, which are mainly used for cooling fresh air in summer.
