Can I stay in a hotel with central air conditioning?

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Recently, the whole country has been frightened by coronavirus, and the pace of life and work has been completely disrupted. The official WeChat account is full of pneumonia-related problems. Today, I drew an official WeChat account of 10w+, and someone in the comment box asked, "Can I stay in a hotel with central air conditioning?" When you suddenly feel really nervous about such a problem, you will have an unexpected panic. Of course, this is also human nature. Therefore, it is a hot spot to catch up with a popular science article before coming back to work these two days.

What is central air conditioning?

To understand what central air conditioning is, we must first understand what air conditioning is. But it goes without saying. Of course. The air conditioner you think is not necessarily the air conditioner you think.

The English name of AirConditioner is air conditioner. As the name implies, air conditioning refers to the equipment that manually controls and adjusts indoor air temperature, humidity, flow and other parameters (from Baidu Encyclopedia). And what we usually call air conditioning is residential air conditioning, which usually only refers to the equipment for adjusting temperature and often refers to the equipment for cooling. The most typical example is our home wall hanging machine.

Take the wall hanging machine as an example. We all know that it is an external machine plus an internal machine. Almost all air conditioning systems can be explained by this model. But in the industry, we call the external machine a cold and heat source system and the internal machine a terminal system. The central air conditioning system is an air conditioning system with relatively concentrated cold and heat source systems and relatively dispersed terminal systems. It can be understood as an air conditioning system in which a few high-powered external machines are dragging a large number of single small-powered external machines.

Central air conditioning in public buildings

In the past, central air conditioning system was used in public buildings, but in recent years, domestic central air conditioning system has been used more and more in the field of home improvement, but it cannot be generalized. If you don't understand the difference between the two, you may not be able to answer this question.

In an architectural design institute, air conditioning belongs to HVAC major, and the full name of HVAC major is heating, ventilation and air conditioning (HVAC), so besides refrigeration and heating, there is also a very important ventilation, which includes many things. The following article will talk about what will be used, such as fresh air, that is, outdoor air; Air supply is fresh air treated by air conditioning equipment; Return air is indoor air that is pumped back to the air handling unit; Exhaust is the exhaust gas discharged to the outside. Besides these, there are other accidents, such as smoke control, positive pressure air supply and so on. My friend who eats melons will ask me why I haven't heard of these.

Because houses are usually only designed for natural ventilation, it is enough to open windows for ventilation in a popular way. Then, because it is not a crowded place and the requirements for fire fighting are not so high, these things are generally beyond reach.

But public buildings are different. Fire prevention should be designed according to size and purpose, but ventilation system is basically indispensable. On the one hand, the energy consumption of window ventilation is high, on the other hand, what should I do in places not close to windows, such as the atrium of shopping malls? We don't need to follow the schedule, but the house won't be built for you unless these things are drawn on the map, and it won't be granted to you if it is built. Therefore, in addition to traditional air conditioning, public buildings also have special fresh air systems to meet the ventilation needs of indoor personnel.

Air conditioning terminal and fresh air terminal

If we call the indoor unit that solves the problem of cooling and heating as the air conditioning terminal and the "indoor unit" that solves the problem of fresh air as the fresh air terminal, these two devices are separated and used by most families. The most commonly used fresh air system in general families is to filter outdoor air and send it indoors, such as a fresh air blower, which was put down after writing a series of articles. Public buildings rarely do this, except for filtration, which usually needs to adjust the temperature. At this time, the fresh air terminal is actually an air-conditioning terminal device, which means that it not only solves the ventilation demand, but also solves a certain cooling and heating demand. Then, since the fresh air terminal can be used as the air conditioning terminal, can we just leave out the air conditioning terminal and use only the fresh air terminal? Of course, this is very common. This is the all-air system, which is widely used in shopping malls. But at this time, the amount of outdoor air that meets the demand for fresh air is still so large, but the amount of air that needs to be treated to solve the temperature problem is much larger. At this time, outdoor air cannot dominate, otherwise the air conditioning load and operating cost will go up to heaven. At this time, the outdoor air has actually taken a back seat, accounting for only 15%-30% of the total treated air volume. At the same time, in order to better distribute fresh air, decentralized air supply and centralized return air are often adopted.

And this is precisely the problem, because a large number of return air, the risk of cross-infection has increased. If someone sneezes, and then the droplets in the sneeze are sucked into the return air system, the machine turns around and comes out of the air supply system, and the air supply is distributed, is the diffusion range much larger?

Of course, it is not absolute. After all, the spread of the virus is a very complicated process. The virus lives alone in the air for a short period. If it is attached to the transmission carrier, it can only survive for a long time until it infects the next person. This carrier includes droplets, including inhalable particles of various sizes, so it is not the virus itself that we wear masks to stop. The virus itself is nanoscale and cannot be stopped. It is these carriers that we want to stop. If the filtering ability of air conditioning equipment is very strong, it is no problem to shield these things, but if it doesn't work, don't you know if it will work? Actually, if I didn't look at the filter, I don't know if I can give it. What is the most common nylon net? You can look at the filter screen of your air conditioner return air outlet.

/* If you can't understand the following paragraph, it won't affect your reading */

/* Air conditioning systems can be divided into water system, air system and air-water system according to the different modes of cold energy transmission and distribution. The water system is that the refrigerant is directly sent to the terminal to treat the indoor air, and the terminal is generally installed in the room to be treated; The end of the air system is centralized, and then the treated air is sent indoors, and the cold energy is transported by wind; Air-water system is a system with both. The air system usually deals with humidity and the water system deals with temperature. */

Then can I stay in a hotel with central air conditioning?

In fact, seeing here, the principle has been paved, and now answer the question of the topic.

First of all, it depends on where the air conditioning wind blows out. If it is a simple indoor unit, this central air conditioner is similar to ours. It absorbs indoor air, sends it indoors, simply circulates it internally, and then independently configures the fresh air system or even does not configure it (window ventilation). From the point of view of air conditioning, there is no problem. This is the configuration of ordinary rooms in most express hotels, middle and low-grade hotels and even high-grade hotels.

Secondly, if the hotel installs an all-air system, it may not be a big problem, because this kind of room usually adopts an all-air system, fresh air and no return air at all.

Third, the risk comes not from the air conditioning system, but from the flow of people. Air conditioning can't solve the disinfection problem. If the last tenant is sick, the source of infection left in the room cannot be expected to be solved by air conditioning. So the country requires you to stay at home as much as possible, so try to stay at home and don't make trouble.

A little advice

In addition to the tips that you can get in touch with in various ways, let's make some suggestions. Be sure to ventilate more. I just read a document tonight. During the SARS period, SARS patients were placed in the corridors of hospitals. As a result, all four doctors in the office on one side of the corridor were sick, but none on the other side was sick. Analyze the reasons. The side that is not sick faces the street and is well ventilated. The diseased side is close to the atrium, and the ventilation is poor. Ventilation can effectively reduce the virus concentration in the air. When the concentration is lower than the safe threshold, even a little inhalation, the immune system may directly repair the virus.

The above content is shared by good users of Li Youcai 0722, I hope I can help you ~