Shulou(Shulou.com)11/24 Report--

Happy New year, everyone, Hi.

On the occasion of the Spring Festival, the editor, as a student in Beijing, was still enjoying collective heating last month, but now he is shivering at home, complaining that he will be frozen xi every time he comes home for the Spring Festival. It turns out that in "Nanshan South"-you are snowing heavily in the southern sun, and I am like spring all the year round in the cold night in the north.

The difference between the north and the south during the winter | the source of the picture comes from the Internet. Awkwardly, the editor is still in a northern city without collective heating. It can only be said that there was a row of radiators in front of me, but I didn't cherish it. I didn't regret it until I lost it, so now I have to turn on the air conditioner remote control.

The picture source comes from the Internet, and as northerners, it is inevitable to wonder how southerners spend the winter. The editor guesses that southerners will also leave envious drool on the radiators of the north. Then the editor will take you to decipher the various heating methods for the north and south of our country to see which are the trumpets you have seen.

01. First of all, the most obvious difference in heating between the north and the south of China is collective heating, which is mainly based on the climate calculation method of the Soviet Union: only the daily average temperature of ≥ 90 days of ≤ 5 ℃ can be defined as the area of collective heating. On the map of our country, it can be shown that collective heating has been basically achieved in the urban area north of the Qinling-Huaihe boundary, while there is basically no collective heating in the south of the Qinling-Huaihe River, and there is a heating mixed war zone in the area through which the line passes. Heating and unheated cities crisscross, Xiaobian and his hometown friends are crying out for their "undress freedom" in winter.

Map of collective heating situation in the north and south of China | the source of the map is able to talk. According to the knowledge of the second grade of primary school, although the winter in the south is relatively shorter and the atmospheric temperature is relatively lower, only the atmospheric temperature is taken into account. however, it is not entirely reasonable not to consider humidity, wind speed and other factors that may affect the somatosensory temperature of the human body. Because the humid weather in the south makes it very wet and cold in winter, and the somatosensory temperature is lower than the outdoor temperature, I would like to congratulate very few southern cities on the implementation of collective heating under the voice of the masses!

The source is from network 02. Winter in northern cities: since collective heating starts with collective heating, let's first talk about the structural principle of collective heating radiator system. As the saying goes, the radiator is called "radiator", which is equipped in most student dormitories in the north of our country.

Among them, the heat source (hot water or steam) of the collective heating radiator system is supplied by thermal companies in the area, heating the water in large boilers by burning coal and other fuels, and then piping hot water or steam to radiators in thousands of households, as shown in the following figure:

Principle of collective heating radiator system | the source comes from the map that can talk, and then the heat source transfers heat to the cavity wall of the radiator by means of thermal convection or condensation, raising its temperature. Finally, the outer surface of the radiator transfers heat to the indoor air by means of thermal convection and thermal radiation, thus generating a continuous stream of heat, raising the indoor temperature and heating.

At the same time, as a collective heating mode, there is also a collective heating ground heating system: its heat source is also supplied by thermal companies, by laying ground heating pipes under the ground decoration materials (solid wood floor, ceramic tile, composite floor, etc.). The heat source transfers heat to the ground through the ground heating pipe, and the heated ground radiates heat to the interior from the bottom up, so as to achieve the purpose of heating.

Two ways of collective heating system | the source of the picture comes from the network. The two heating modes are mainly air thermal radiation, supplemented by thermal convection. Of course, put your hands directly on the radiator, or your feet on the floor, you can also keep warm, which is the way to use heat conduction.

Since the source of the picture comes from the network, since we have talked about it here, we might as well revisit the thermal knowledge of the second grade of primary school, that is, heat transfer is divided into three ways: heat conduction, thermal convection and thermal radiation. this part of the high-frequency required test content has been mentioned in the previous article, forgotten people, please click below to check! "with my cold hands and scalded mouth, I was fantasizing about holding the thermos cup. "

In general, the use of heat conduction is not easy to heat a large range of space, the efficiency of thermal convection for long-distance heat transfer is very low, and the heat transfer speed of thermal radiation is the fastest. These three ways of heat transfer generally exist at the same time and occur at the same time, but each has a different proportion in heat transfer. For example, the following bowl of hot soup, whose heat transfer is mainly through thermal convection and thermal radiation, accounts for a very small proportion of heat transfer.

Three ways of heat transfer | the source is from network 03. Northeastern people spend the winter: after reviewing the theoretical knowledge of "hot", let's take a look at the "Kang" culture with northeast characteristics.

The fire Kang with northeast characteristics comes from Hongzong China, "people from the south live in the bed and people from the north sleep on the Kang". Among them, the structure of the fire Kang is to build several small walls on the ground, divide the space into several tunnels, leave space at both ends to make the road communicate, and then cover it with brick. then put dirt on the brick cover and reuse sand and mud to level it. One end of the Kang body is provided with a stove, one end leads to the chimney, in which the stove is the heat source, the Kang body is the heat dissipation component, and the chimney is the smoke exhaust component.

When cooking or heating in the stove, the high temperature flue gas flows through the interior of the Kang body, heats the Kang body, raises the surface temperature of the Kang body, and radiates heat from the surface of the Kang body to the interior. After the heat of the smoke in the Kang body is fully exchanged with the Kang body, it is discharged to the outdoor atmosphere through the chimney. When people lie directly on the stove, they keep warm by means of heat conduction. But the side of the body that touches the stove will be very hot, and the side far away from the stove will receive less heat. So turn over and over again and heat it evenly, like the picture below. (slowly type a question mark)

In the rural areas of our country, several generations are generally under the same roof, so "even the Kang" is important, including the influence of Chinese traditional culture. Since the heat transfer efficiency is less than 100%, the position near the side of the pot and stove, commonly known as "Kang Tou", is the hottest, so it is for the owner of the highest generation in the family to sleep, while the side near the chimney is relatively less hot. It is used by the younger generation in the family to live or dry food. At this time, the Kang is not only a bed, but also a space with affinity, so the Kang culture is also a microcosm of the northeast culture.

Even four stoves | Picture Source Literature [6] 04. Northwestern people spend the winter: "Fire Wall" after seeing the fire Kang in the northeast, then let's take a look at the northwest characteristic "fire wall". In fact, the principle of the fire Kang is similar.

When designing bungalows in Northwest China, the location of the fire wall will be considered, the wall between the two rooms will be designed as hollow, and a labyrinth of flues will be built with small earth clods. the roof is a chimney, and there is a stove under the wall. or connect the kitchen stove under the floor. Due to the chimney effect, the cold air drills into the stove from below, which makes the coal burn vigorously. The smoke passes through the labyrinth of fire walls, heating the walls through thermal convection, and the walls raise the indoor temperature in the form of thermal radiation to achieve the purpose of heating.

The structure of the fire wall | from the network summary, collective heating is the welfare of northerners, as long as you pay the fee on time every year, you can enjoy a comfortable heating life, which can be said to be a very good way of heating; in the south, due to the lack of perfect heating facilities, there is no difference between indoor temperature and outdoor temperature, so it is a little difficult in winter. But! Southerners also have their own set of "combination boxing" to deal with the cold winter.

05. Southerners spend the winter: "combination boxing" because there is no collective heating to limit everyone's imagination, southerners' heating methods can be described as letting a hundred flowers blossom, such as split air conditioners, wall-mounted floor heating systems, heaters, removable electric heaters, fire pots, etc., facing the cold air is a set of "combination fists".

A set of combination boxing | the image source comes from the first type of network combination boxing.

First of all, the air conditioner is the familiar air conditioner, how happy it is to have an air conditioner remote control.

The following picture shows the most basic heating process of the air conditioner, the working medium is first compressed into a state of high temperature and high pressure, exothermic reaction occurs on the side of the condenser, hot air is blown out, and then flows to the evaporator side to absorb heat, blow out cold air, and recycle repeatedly. Due to the main use of thermal convection, a more appropriate temperature will be felt near the air outlet of the air conditioner, and the temperature will be quite different in other areas and areas without air conditioning heating.

Schematic diagram of the principle of air-conditioning heating | the picture is derived from the second style of Zhihu combination fist.

The next guest of the wall-mounted furnace floor heating system is the wall-mounted furnace floor heating system, which works similar to the central heating system, except that the heat source has been changed from the heat company to the wall-mounted furnace. The wall-mounted furnace usually uses natural gas as the energy source and produces hot water of 40 to 75 ℃. The hot water flows continuously in the pipe through the built-in circulating water pump, raising the temperature of the ground by means of heat convection and heat conduction, thus achieving the effect of heating.

The third style of combination boxing

Southwest characteristics: fire bucket above both are the way of heating the whole house, the power (energy consumption) is larger. Part of the time is mainly aimed at local heating, the following will introduce the way of local heating, first to introduce the southwest characteristics of the "fire bucket".

The "fire bucket" is generally a round wooden bucket with a hollow inside. There is a fire-insulating and load-bearing iron fence (wooden fence) in the middle and bottom of the bucket, and a charcoal brazier is placed under the grille, and the bottom of the charcoal brazier may also be covered with bricks for thermal insulation. In winter, people will build a board across the fire bucket to sit on it, the principle is to use the thermal radiation of charcoal fire for heating, and the fire bucket can be moved at will, and the living room can be brought back to the bedroom after use.

Fire bucket | Picture source: besides fire kegs, Nanshan Qiaosong also has fire pots, fire cabinets and other cold protection devices, all of which are heated by open fire or charcoal burning. Although it is convenient to obtain raw materials, there are safety risks such as fire. With the development of science and technology and the improvement of people's living standards, electric heating has gradually replaced these methods, but we still need to pay attention to them when using them.

The fourth style of combination boxing

The next scientific and technological product of the heater is the heater, which works similar to a large hairdryer. When there is no flammable and explosive gas in the air, it can heat the air nearby by circulation. The fan is used to inspire the air to flow through the electric heating element to force convection, and then the heated air is sent out through the air outlet, so as to achieve the purpose of heating.

Radiator | the source comes from the fifth type of network combination fist.

When it comes to plug-and-play portable electric heaters, Little Sun must have a place. Because its red circular reflector is very similar to the sun, it is named "Little Sun", while the vertical little sun is called "electric fan" in some areas. When working, the heating body (quartz tube) is heated by electricity, and then the reflector is used to reflect the heat and infrared ray directionally to achieve the purpose of heating. Because it is easy to use and the price is good, it is deeply loved by the broad masses of the people, but it often has hidden dangers such as burns and fires in meetings, so you need to be extra careful when using it, and remember to cut off the power after use. The plus version of Xiao Sun can also have a "bird cage", which can radiate heat around. According to students in the south, it can not only warm milk, but even bake egg tarts. (northerners expressed great shock)

Little Sun and Birdcage | the source comes from the sixth style of network combination boxing.

It remains to be seen whether the electric heating table can bake fragrant egg tarts, but the enhanced version of the birdcage "electric heating table" can roast smelly jio. It not only has the warm foot function of heat conduction to move the soles in spring, but also the roast leg function brought by the thermal radiation around. (it is the envious drool of the electric heating table). As the integrated light of human protection from the cold, the electric heating table also has a temperature control and protection system, and the power will be cut off automatically if the temperature is too high. For clothes that cannot be dried in the south for a week, the heating table is also equipped with a drying function (see picture below), which must be highly recommended.

Foot warmer, birdcage and electric heating table | the source is from the network.

Actual patting of the electric heating table | the source comes from the seventh style of litchi jelly combination fist.

The last portable electric heater on the stage is "ting", which is similar to the "heat sink" in the north, but can be moved at will. The electric heating pipe is installed inside the cavity of the radiator and heat conducting oil is injected around the electric heating pipe in the cavity. When the electric oil is connected to the power supply, the heat conduction oil around the electric heating pipe is heated and rises to the upper part of the cavity, circulates convectively along the heat dissipation tube or radiator, heats the cavity wall, and finally radiates the heat through the surface of the cavity wall, so as to achieve the purpose of heating.

Electric fuel Ting | the image source is from network 06. Sanya people spend the winter: if there is no winter, don't forget the Sanya people in the south, it is really too difficult for them to spend the winter. Because they don't have winter, they can't feel the joy of making snowmen and skating. If they want to spend the winter, the round-trip ticket to the north may be more expensive than the heating fee in the first quarter of the north.

According to China's solar terms, winter begins with "the Beginning of Winter" and ends before the next "the Beginning of Spring". However, if the winter is divided according to the air temperature method: when the daily average temperature is lower than 10 ℃ for five consecutive days, and ends when the daily average temperature rises steadily to more than 10 ℃ for five consecutive days, then Sanya does not have a situation of less than 10 ℃ for five consecutive days in recent years, so the way for people in Sanya to experience winter is to buy air tickets to travel.

There are also many ways of heating from outside the Internet. For example, some Western European countries advocate solar heating because of the lack of fossil resources and the high price of fuel. Using solar cells to convert the collected solar energy into electricity, and then use it, the whole process is clean and environmentally friendly. Low temperature radiation electric heating film heating system is very popular in South Korea and has been used in our country.

However, the most direct way to keep warm is to listen to your mother and wear more pairs of woolen trousers and long johns. After rummaging through the house and the bed with an electric blanket, it can be regarded as a low-equipped version of the hot Kang. And the foot warmer under the table, the hot water bag on the hand, the warm baby sticker on the belly, and so on, are almost soldered on the body. It is really powerless to resist the cold, so hurry up and start school (bushi).

The source comes from Zhihu: a rapeseed reference:

National heating and Energy production, National Bureau of Statistics: http://www.stats.gov.cn/

Zhang Yongjiang, Deng Yunhai. Performance comparison and selection of common indoor heating methods [J]. Polyvinyl chloride (PVC), 2020548 (11): 9-12.

Yao Bin. Analysis on the choice of heating mode in winter [J]. Doors and windows, 2018 (02): 53.

Li Ruijun. The influence of heating methods on the Spatial form of traditional dwellings in Northern China [C] / /. 2013 Proceedings of Chinese Interior Design.

Gao Xiangxiang, Hu Bianbu, Liu Jiaping. Study on Indoor Thermal Environment of Kang dwellings in North China in Winter [J]. Architectural Science, 2010, June 26 (02): 37-40.

Wang Xiaocoo, Zhou Ning, Hu Wenhui. A brief Analysis of the traditional Northeast Kang Culture [J]. Shanxi Architecture, 2010. 36 (13): 1-2.

This article comes from the official account of Wechat: Institute of Physics, Chinese Academy of Sciences (ID:cas-iop), author: TT

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