New ideas should be introduced in the design of clean air conditioning system in hospitals.
The following are summarized as follows: the purification of air conditioning is effective and irreplaceable for the infection control of the air way; a clean air conditioning system should be less expensive; the concept of pollution degree is introduced to reduce the air pollution in the key areas while reducing the air supply volume of the high purity level. The wind ceiling creates a one-way flow pattern in the key areas to reduce air pollution in key areas. The new air system uses two independent primary and medium efficiency filters, and adopts constant air volume valves to ensure positive pressure distribution inside the room.
The task of hospital air conditioning should be:
Maintain the required indoor climate and remove dust, microorganisms, odors and harmful gases from the air. Air conditioning in hospital operation room is the most important and difficult task, especially the postoperative infection caused by air control. It is very important to reduce and avoid postoperative infection, which is the key to ensure the success of operation, shorten the recovery time of patients and reduce the cost of medical treatment. In addition, another feature of the air conditioning is that the service area is small, but the air volume is large, the energy consumption is high and the use time is uncertain. Therefore, the air conditioning system should pay special attention to the energy conservation of the air-conditioning system while creating a highly clean indoor climate.
The following is a case study of the design of a hospital in Wuhan City as an example to introduce the design ideas embodied in the design.
I. General Situation
The clean operation Department is composed of eight rooms, including the central hall, the anesthetic room, the recovery room and so on. The operation Department is located on the two floor of the medical technology building, with no external enclosure structure. The purification level is respectively 1000 (I), 1, 10000 (II), 4, one hundred thousand (III) 3. At Tn=24 ~ 28 C, it can be adjusted in the operating room and the relative humidity is n=50% to 60%.
Two. Partition of air conditioning system
1. the high level air conditioning system should be set up independently. The so-called "high level" refers to the level of more than 1000 level. The reason is that the air supply capacity of the high level air conditioning is large, just like the size of the area. The air volume of the 100 level air conditioner is 3.4 times of the one hundred thousand level, and 2.25 times of the 10000 level. In addition, the use frequency of the high level is far lower than that of the low level, so that no matter whether an air-conditioning system bears many high levels, or an air conditioning system bears a high level and multiple low levels, it will make the air conditioning system run in the "big horse" car for a long time. For example, an air conditioning system will bear 1 hundred level and 2 10000 level or 4 one hundred thousand levels. If the high level is not used, then the system design air volume is at least 112% and 84% of the required air volume at that time. That is to say, the required air volume of the system is only 47% and 54.3% of the designed wind volume of the system. Frequency speed regulation can only adjust the air volume by adjusting the main air valve to adapt to the change of air volume in the system. However, this method obviously does not save energy. Therefore, from the point of view of energy conservation or from the point of view of reliability and flexibility, the high level air conditioning system should be set up independently, i.e. a clean air conditioning system corresponds to one.
2. for the lower level, although the air conditioning volume is much smaller than that of the high level, there is not enough air conditioning system to bear too many air conditioning systems, because the use of hospital equipment is uncertain. The higher the hospital is, the more it needs to meet the special busy situation. When the air conditioning system is in excess, the system is always in a state of "oversupply", and its operation energy consumption is bound to be higher, just as some hospitals reflect "built up can not afford to use". The author believes that for a low-level operation room, an air conditioning system shoulds not be more than four to five, and the burden of a system is too much, which will also lead to unreliable use.
3. the central cleaning hall, clean corridor, preparatory area and asepsis room of the high level operating room should be borne by a separate air conditioning system. The purpose is to ensure that the external air environment of the asepsis room is always in a "combat" state. The practice of incorporating the above parts of air-conditioning into the low-level air conditioning system is obviously unreasonable. Because the air conditioning system that is combined, or when the system is stopped, the energy consumption of the system is too large, or the external environment is not guaranteed.

In a word, the division principle of air conditioning system in operation department should be reliable operation, flexible adjustment, responsibility of each department and energy saving.

3. Determination of Air Supply Volume and Air Distribution
When the air conditioning system was designed by the Department of surgery in the hospital, the state did not publish the standards and specifications for the clean air conditioning design of the operation room. At that time, the design of clean air conditioning for hospital operation room was basically confined to the design idea of the industrial cleanroom. However, the design of the industrial cleanroom was moved to the hospital clean air conditioning design, which brings two problems:
(1) high class cleanroom air volume is too large, for example, according to the code for design of clean workshops (hereinafter referred to as the code), 100 level should be in the ceiling full of high efficiency filter outlet, then a 36m2 air supply volume of 32400m3/h~45360m3/h (corresponding section wind speed is 0.25m/s~0.35m/s), such a large volume of air supply, air supply power consumption up to 17.0kW~19.0kW, send and return air duct takes up building empty. It is difficult to control the noise of the wind system because of the large interval.
(2) under the same air volume, under the same level of air pollution, the pollution control in key areas is not ideal, because the air distribution in the "specification" below 1000 level can be used in turbulent flow. The usual method is to set uniformly the air outlet of the high efficiency filter on the roof of the whole room. The theoretical basis of this air distribution form is "whole room dilution and purification". However, according to the concept of pollution concentration in German standard DIN 1946/4, this air distribution form of "whole room dilution and purification" can achieve the same bacterial concentration in the room under ideal conditions. At this time, the degree of pollution is 1. Breakthrough in the "whole room dilution and purification" of the industrial cleanroom air distribution mode, will be in the operation room key areas to get a lower degree of pollution.
In view of the above problems, designers refer to the experience of Weiss air conditioning system in Germany. In terms of air volume calculation and airflow organization, the designer breaks through the design idea of industrial cleanroom, introduces the concept of reducing total air volume and strengthening local air supply, focusing on the design concept of the operating bed and instrument table area.
A. for all levels of operation room, the concept of whole room dilution and purification was broken through, and local intensified purification was introduced. All the air outlets of all the operation room were arranged above the operating table, namely, the "laminar flow bellows" were set at the center of the shadowless lamp suspender, and different air supply section sizes were adopted according to different grades.
B. for 100 or 1000 level, the area of clean airflow is covered by the area and the wind speed is determined by the cross section wind speed. For example, the 1000 square meters of the project adopts the air supply laminar flow box with an area of 2.4m * 2.4m, and the section velocity is 0.35m/s, so the air supply is 7258m3/h. If it is a hundred class, the air supply laminar flow box is covered by 3.0m x 3.0m, and the section velocity is still 0.35m/s. The air supply volume 11340m3/h is only 40% of the calculation method of the industrial cleanroom mentioned above. Although this design idea draws lessons from the experience of Weiss air conditioning system in Germany, this project does not adopt the method of large area and small air volume (i.e. large area and low wind speed) introduced by German scholars, because according to the specific situation of domestic hospitals, the requirement of objective conditions is too harsh when using small wind speed, and when the wind speed is small, there is not enough momentum to maintain the air supply. It is difficult to achieve ideal air conditioning and purification effect by convection. When the cross-section wind speed is 30.35m/s, if the return air outlet is set properly, not only can the supply air maintain a better one-way flow pattern, but also its one-way flow diversion height will be less than 0.6m, that is, the diversion height is lower than the operating surface elevation of the operating bed.
C. is used to determine the air supply volume for the ten thousand and one hundred thousand levels by air exchange method, ten times n=30 times /h, and one hundred thousand times n=20 times /h. Although this ventilation frequency is the lower limit value stipulated in the Code, the concentration of bacteria in the operating area is 50% of that in other areas of the room, which means that the air pollution in the operating area is reduced from 1 of the whole room dilution and purification mode to 0.5 of the locally enhanced air supply mode because of the use of the laminar air supply box above the operating bed. The air supply area of the "laminar air supply box" for the project is 2.4m * 1.2m and 1.5m * 1.5m respectively, and the wind speed of the cross section is one hundred thousand 0.35m/s.
In conclusion, the hospital with the above design idea has achieved good results after being put into use, and achieved a cleaner and more hygienic climate in the key areas (operating beds and instrument table areas) with smaller air volume.
IV. Solving Air Balance Problem by Constant Air Valve
The pressure distribution in different parts of the surgical department has great influence on ensuring the effectiveness of cleaning. However, how to ensure reasonable pressure distribution, besides the correct calculation of air balance, is more important. In the past, the air volume regulating device mainly used to open multi-leaf control valve manually. This kind of valve is not ideal for precise air volume regulation. In practice, it is difficult to adjust and has a long debugging period. To solve this problem, the air supply and return air pipe of the children's hospital air conditioning system adopts the self-made constant air volume valve of German TROX company. This valve can automatically eliminate the influence of air duct pressure on the air volume, and the air volume adjustment dial outside the valve body is very convenient to adjust. After installing the valve, the pressure adjustment of the valve becomes very simple, and the field needs almost no time to adjust the pressure. 。
V. Concluding remarks
In short, designers should learn from the advanced experience of other countries and combine the specific conditions of our country with the principles of "reducing air volume, improving efficiency, saving energy, adjusting and improving reliability". The above five aspects have been tried and proved to be successful in practice.
Shandong aide purification engineering Limited by Share Ltd is a professional hospital building operation room, ICU, disinfection supply room, blood purification center, venous distribution center, CDC, digital integrated operation room, interventional therapy, positive and negative pressure, radiation protection, obstetrics, infant ward, burn ward, Department of medicine, laboratory, pathology, plastic surgery. The business scope of high-tech enterprises in purification projects mainly covers the design and construction of medical building decoration and decoration engineering, central air conditioning engineering, electrical engineering, intelligent engineering, water supply and drainage engineering, gas engineering, etc. The company integrates professional program design team, perfect supporting product channel, professional system construction team and perfect after-sale service. With relevant construction qualifications issued by the national construction department, an experienced R&D team of Engineering technology, relying on years of professional accumulation in the field of purification, combined with the construction management practices of many domestic projects, to provide comprehensive high-quality technical support for domestic customers. If you want to know more about the workshop purification construction, you are welcome to communicate with the project engineers in detail. For more knowledge of medical purification industry, please pay attention to the public address: Aide-188 (Ed purify oxygen supply).