KR102054398B1 - Fine dust removal and sterilization system using salt water - Google Patents

Abstract

The present invention relates to a fine dust removing and sterilizing system using saline water, comprising: a plurality of suction fans placed at one side of a structure having a tower shape, a horizontal shape, or a pergola shape in order to suck air in the outside; a spray nozzle formed inside the structure in order to spray saline water; a drain filtering screen precipitating fine dust by mixing the same with the saline water; and a purified air outlet discharging clean air of which fine dust is removed by the filtering screen to the outside, and capable of sterilizing bacteria or virus container in the air, and minimizing maintenance costs by collecting rainwater in an energy self-sufficient type or installing a photovoltaic power generation device in the external side of the structure. Therefore, the fine dust removing and sterilizing system using saline water can prevent freezing of water in winter with low temperatures by capturing and condensing fine dust by using saline water in the inside of a large-sized structure in order to remove the fine dust frequently generated over winter and spring; can provide pleasant feeling of being in a forest even in a city by including scent of an extract extracted from a needleleaf tree, etc.; can be automatically actuated by a fine dust detecting sensor and be remotely controlled; can provide a lot of people with clean air from which fine dust is removed by installing a structure having a tower shape, a horizontal shape, or a pergola shape in a public facility or a public organization such as a crossroad with traffic, the subway, a school, an expressway service area, an airport, a park, a sports field, and a gym; and can minimize maintenance costs by installing a photovoltaic power generation device in the external side of the structure and recycling rainwater as saline water.

Description

Fine dust removal and sterilization system using salt water

The present invention relates to a system using a salt water to remove and sterilize the fine dust in the air, and more specifically, to form a plurality of suction fans on one side of the structure consisting of tower or horizontal structure or pagora form, etc. Inhaling air from the atmosphere, spraying salt water from the injection nozzles formed inside the structure, mixing fine dust and salt water to settle on the drain filtration screen, and clear air from which the fine dust is removed by the filter medium screen is passed through the purge air outlet. Removal of fine dust using salt water, which can be discharged to the outside and sterilize bacteria or viruses contained in the air, and can collect energy-independent rainwater or form a photovoltaic device outside the structure to minimize maintenance costs. Relates to a sterilization system.

In general, particulate matter or dust is dust that is small enough to be invisible and is an air pollutant containing sulfurous acid gas, nitrogen oxides, lead, ozone, carbon monoxide, and the like. Fine dust is a fine dust with a particle diameter of 10 ㎛ or less that occurs in an automobile, a factory, and floats in the air for a long time, and is also called PM 10. If the particle is 2.5㎛ or less, it is written as PM 2.5 and is also called 'ultrafine dust' or 'ultrafine dust'. Academia is called aerosol. Fine particles are also called suspended particles, particulate matters, etc. and have slightly different meanings depending on their names. Particles have a diameter of 100 μm to 10 nm, and larger diameters have very short residence times in the atmosphere due to gravity. In addition, fine dust is a small substance that is invisible to our eyes and is a particulate matter with a diameter of 10 μm or less floating or scattering in the air. Fine dust is a substance that greatly affects the human body.

The sources of fine dust are classified into artificial and natural occurrences. The reasons for the artificial occurrence may be fine dust from China or the incineration of smoke from the factory. Natural causes are due to sand dust, volcanic ash, and dust from wildfires. Sea salt particles also have a significant effect on areas near the sea.

In modern times, due to urban development and industrial development, pollutants generated from factories and vehicles are excessive in the air, and the damage and discomfort caused by fine dust have reached the limit. In particular, fine dust penetrates deep into the respiratory tract of the human body, causing respiratory diseases such as asthma, bronchitis, and allergic rhinitis, or as a major cause of eye diseases such as conjunctivitis and dry eye syndrome, and allergic rhinitis of skin diseases. It has a bad effect such as to make them, and especially the infants, adolescents, elderly people are vulnerable to fine dust.

Air pollution, which killed 20 people in Donora, Pennsylvania, in 1948, and London Smog, which caused about 4,000 deaths in 1952, are examples of how fine dust affects the human body. Since then, various epidemiological investigations have been conducted on the effect of fine dust on the human body. Particularly, the fine dust particles (PM 10) of 10 μm or less have the potential to have harmful effects on the human body, such as increasing the incidence and mortality of vulnerable groups. It turns out big. After the results of these studies, governments have started to prepare air pollution measures, and air pollution standards are being prepared to reduce the harmful effects of fine dust on the human body and the environment.

In order to minimize the damage caused by the fine dust, a large amount of money has been put into research on fine dust, but the effect is insufficient so far, there is a problem that the damage caused by fine dust increases.

As a prior art related to the removal of fine dust as described above, the fine dust mixed in the air in Korean Laid-Open Patent Publication No. 10-2010-0095890 absorbs moisture generated by condensation of condensed water and uses air to absorb air. An air purifying device for filtering fine dust is disclosed, and after first processing dust, fine dust and odor in Korean Registered Utility Model Publication No. 20-0425412, the odor gas is mixed with a purifying solution to maintain residence time and Disclosed is a pollutant gas purification device using a deodorizing tower and a mixing system configured to increase the contact area to improve pollutant gas purification performance and to extend the replacement cycle of the purifying solution, and has been disclosed in Korea. Gas treatment chamber installed in the polluted gas transfer path to treat and discharge the polluted gas introduced into the arc, and electromagnetic wave into the gas treatment chamber. And a heat generating and temperature control unit for maintaining a uniform temperature inside the gas processing chamber, and a plasma generator for maintaining the inside of the gas processing chamber in a plasma state. Air pollution pollutant gas and fine dust removal system is disclosed, and the cost is increased due to frequent replacement of the filter because it is configured in the method of spraying water or using a filter in Korea Patent Publication No. 10-2018-0027128 In order to solve the problems of the prior art fine dust removing device and air purifying device, which has been troublesome, the overall device configuration is complicated and the energy consumption is high, using the principle of Vortex Tube, Nanobubble water particles are injected together into a vortex tube The external air passes through the inside of the vortex tube to maximize the contact time and area so that fine dust can be effectively removed, thereby improving the effect of fine dust and air purification with a simple configuration and low cost without requiring additional power. Disclosed is a fine dust removal apparatus using a vortex tube and an air purification system using the same.

However, the above-mentioned prior arts have a problem in that a complicated configuration for removing fine dust is difficult to install and an increase in cost. Therefore, in the present invention, an environment-friendly method using a system for removing and sterilizing fine dust using salt water as described above is provided. Completed with technical configuration applicable to general fine dust removal method.

The present invention has been made to solve the above problems and to complement the prior art, public intersections or public institutions such as intersections or subway stations, schools, etc., where traffic is frequently used to remove fine dust that frequently occurs over winter and spring. Injection nozzles formed on the inside of the structure by inhaling air in the air by forming a plurality of suction fans on one side of a structure consisting of a tower form or a horizontal structure form or a pagora form in a highway rest area, an airport, a park, an athletic stadium, a gymnasium, etc. Sprays salt water from the water, mixes fine dust and salt water to settle on the drain filtration screen, and removes the fine dust removed by the filter medium screen to the outside through the purge air outlet to sterilize bacteria or viruses contained in the air. Fine dust using salt water configured to enable this To provide for removal and disinfection systems for the purpose.

As a solution of the fine dust removal and sterilization system using the salt water of the present invention, the air containing fine dust and ultrafine dust is inhaled from various components included in the air to purify the air from the inside and clean air to the outside. In constructing a fine dust removal system that is formed in the discharge tower or horizontal type or indoor type or road type or pagora type, one side of the outer front surface of the tower body 10 is composed of a plurality of intake air containing fine dust to the inside A suction fan 110 is formed, and on one side of the top front surface of the tower body 10, a detection sensor 115 is formed to detect external fine dust, and a plurality of holes are formed on the front surface of the top body 10. The perforated plate screen 101 formed by perforation is formed, and the salt water moved along the pipe 104 and the pipe 104 for moving the salt water. A spray nozzle 103 for injecting the inside of the tower body 10 is formed on the upper side, and the pipe 104 is connected to the storage tank 160 formed at the lower end of the tower body 10, and the salt The pump 105 is formed on the side of the storage tank 160 in which the water is stored to move the salinity water inside the storage tank 160 to the pipe 104, and two to three on the inner rear of the tower body 10. The filter medium screen 102 is formed, and one side of the outer side rear surface of the tower body 10 forms an outlet 120 configured to discharge a plurality of purified air to the outside, and the outer side rear surface of the tower body 10. On one side of the outlet sensor (125) to detect the external fine dust is formed, the upper portion of the storage tank 160 forms an input unit 140 for storing and injecting sodium chloride and fungicides and additives, the input Salt water containing fine dust on the upper portion 140 Forming a drain filtration screen 130 to purify, the drain filtration screen 130 is connected to the drain discharge pipe 135 to discharge the pollutants, the photovoltaic unit 180 on the outside of the tower body 10 ) And a rainwater inflow portion 150 is formed at the outer upper portion of the tower body 10 and connected to the storage tank 160, and a controller 170 is formed at the outer lower portion of the tower body 10 to form a tower body. (10) to control.

The control unit 170 is capable of controlling the fine dust removal system formed in the tower or horizontal or indoor or road or pagora shape of the present invention, and can be controlled remotely using a wired or wireless communication at a long distance, the input unit ( In 140, sodium chloride, a fungicide, and an additive are added to the salt water stored inside the storage tank 160 formed below.

The storage tank 160 may further provide a salt water sprayed through the spray nozzle 103 by connecting the water supply pipe 145 and the rainwater inlet 150. That is, the salt water sprayed through the injection nozzle 103 of the present invention usually uses rainwater collected through the rainwater inlet 150, and the amount of rainwater collected through the rainwater inlet 150 is less. At this time, water supplied from the water supply pipe 145 may be used.

The perforated plate screen 101 is formed by perforating a plurality of holes in the range of 0.5 ~ 5㎜ in diameter, the filter medium screen 102 by selecting any one or more of activated carbon or metal filter or fiber filter or wood chips to fine dust Collect.

Looking at the operation of the tower in the fine dust removal system formed in the tower or horizontal or indoor or road or pagora configuration configured as described above, the fine dust contained in the air from the sensor 115 formed in front of the tower body 10 Alternatively, when the ultra fine dust is detected and notified to the controller 170, the controller 170 starts the operation of the suction fan 110.

The suction fan 110 may be installed in plural numbers according to the size or size of the top body 10, and the suction fan 110 sucks air containing fine dust or ultrafine dust into the top body 10. . The sucked air passes primarily through the perforated plate screen 101. The perforated plate screen 101 is formed of a plurality of pores having a diameter of 0.5 ~ 5㎜ to filter out air containing fine dust or ultrafine dust first. Air passing through the perforated plate screen 101 passes through the salt water pouring from the injection nozzle 103, which is the inner upper portion of the columnar body (10). The salt water has an effect of washing the fine dust or ultrafine dust in the air and freely drop the fine dust or ultrafine dust in the air with the salt water to the bottom of the tower body (10). Air passing through the salt water sprayed from the injection nozzle 103 for the second time passes through the filter medium screen 102 composed of two to three in the third.

The filter material screen 102 is configured by selecting any one or more of activated carbon or metal filter or fiber filter, wood chip, ceramic, zeolite or sand, and may be configured in various forms to collect fine dust or ultra fine dust, Easy to replace

Air passing through the filter medium screen 102 composed of two to three as described above is clear and pure air containing no fine dust or ultrafine dust passing through the outlet 120 and exits to the outside of the tower body 10. will be.

Fine dust or ultrafine particles free-falling together with the salt water sprayed from the injection nozzle 103 arrive at the drain filtration screen 130 formed at the bottom of the tower body 10 and the drain filtration screen 130 Pass). The salt water passing through the drain filtration screen 130 is collected and recycled to the storage tank 160 again. In addition, the fine dust or ultra-fine dust, etc. that do not pass through the drain filtration screen 130 is filtered by the drain filtration screen 130 is discharged through the drain discharge pipe (135).

The salt water collected in the storage tank 160 through the pump 105 on the side of the storage tank 160 moves to the upper end of the tower body 10 along the pipe 104 to use the injection nozzle 103. It is sprayed to the inner side of the tower body 10.

Detecting sensor 115 and the outlet sensor 125 formed on the front and rear of the tower body 10, respectively, to detect the fine dust or ultra-fine dust to the control unit 170 located in the lower portion of the tower body (10) Notification and the control unit 170 analyzes this to control the tower body (10). The controller 170 may control remotely using wired or wireless communication. That is, it is possible to control a plurality of tower body 10 in one control room, such as a situation room.

The rainwater inlet 150 extending from the upper end of the tower body 10 to the inside is a storage tank 160 formed on the inner lower portion of the tower body 10 by collecting rainwater falling on the upper end of the tower body 10. Supply. Inside the rainwater inlet 150, a filter is further configured to purify the rainwater to move to the storage tank 160, and the tower body 10 is operated by using the rainwater supplied by the rainwater inlet 150. And, if the drought or rain water is significantly less than the tower main body 10 can not be operated by using the water supplied from the water supply pipe 145 can operate the tower main body 10.

In addition, the photovoltaic unit 180 may be formed outside the tower body 10 to cover power consumed by the tower body 10.

As described above, the tower body 10 according to the present invention may use rainwater for salt water, and power is consumed through the photovoltaic power generation unit 180, thereby forming a fine dust removal and sterilization system using environmentally friendly and independent salt water. You can do it.

In the present invention, the fine dust removal and sterilization system using the salt water captures and aggregates the fine dust using the salt water inside the large structure in order to remove the fine dust which occurs frequently in winter and spring in Korea. It can prevent the freezing of water and contain the fragrance of extract extracted from conifers, so you can feel the freshness of the forest even in the city, and the system is automatically operated by the fine dust detection sensor, and it can be controlled remotely. Or by installing structures in the form of towers or horizontal structures or pagora in public facilities such as subway stations, schools or public institutions, highway rest areas, airports, parks, sports stadiums, gymnasiums, To supply clean air without dust And recycling the solar system and rainwater, etc. on the outside of the structure can be used as a salt, so the effect can be minimized maintenance costs.

1 is a top cross-sectional view of the fine dust removal and sterilization system using the present inventors salt water.
Figure 2 is a tower configuration of the fine dust removal and sterilization system using the present inventors salt water.
Figure 3 is a horizontal configuration of the fine dust removal and sterilization system using the present inventors salt water.
Figure 4 is a block diagram of the indoor dust removal and sterilization system using the present inventors salt water.
Figure 5 is a road configuration of the fine dust removal and sterilization system using the present inventors salt water.
Figure 6 is a pagora configuration of the fine dust removal and sterilization system using the present inventors salt water.

DETAILED DESCRIPTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and embodiments, and in the following description, when it is determined that a detailed description of a related well-known function or configuration may unnecessarily obscure the gist of the present invention. Detailed description thereof has been omitted.

Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

1 is a cross-sectional view of a fine dust removal and sterilization system using salt water, Figure 2 is a top configuration diagram of a fine dust removal and sterilization system using salt water, Figure 3 is a fine dust removal and sterilization system using salt water 4 is an indoor configuration diagram of a fine dust removal and sterilization system using salt water, FIG. 5 is a road configuration diagram of a fine dust removal and sterilization system using salt water, and FIG. Pagora configuration diagram of the fine dust removal and sterilization system,

Referring to Figure 1 and 2 in detail,

The configuration of the tower-shaped body 10 configured in the form of a tower is formed on the front surface and comprises a suction fan 110 composed of a plurality of suction air inside including fine dust and the detection sensor 115 installed on the front to detect the fine dust And a perforated plate screen 101 formed by drilling a plurality of holes in the inner front, a pipe 104 for moving the salt water, and a spray nozzle 103 for spraying the salt water moved to the pipe 104 to the inside. Filter outlet screen 102 formed on the inner rear and the outlet 120 formed of a plurality formed on the rear and discharge the purified air to the outside and the outlet detection sensor 125 and the front lower portion installed on the rear to detect fine dust Storage tank 160 for storing the salt water in the control unit 170 and the inner lower portion formed in the pump 105 and the storage tank for supplying the salt water to the pipe 104 on the side of the storage tank 160 Forming on top of 160 Is connected to the drain 140 and the drain filtration screen 130 formed on the input unit 140 and the drain filtration screen 130 is formed on the drain discharge pipe 135 and the upper to discharge the detected dust The rainwater inlet 150 is formed on the outer side and comprises a solar power generation unit 180 capable of self-power generation.

Air sucked by the suction fan 110 formed on the front surface of the tower body 10 passes through the perforated plate screen 101 and passes through the salt water sprayed from the injection nozzle 103, consisting of two to three Passing through the filter medium screen 102 and exits to the outside of the columnar body 10 through the outlet 120.

While passing through the salt water sprayed from the perforated plate screen 101 and the spray nozzle 103 and the filter medium screen 102, fine dust or ultrafine dust or various bacteria, viruses, etc. contained in the air are removed, purified and sterilized. It is to release fresh air.

The input unit 140 is mixed with sodium chloride, fungicides and additives to the water supplied through the rain water or water supply pipe 145. The amount of sodium chloride introduced into the storage tank 160 from the input unit 140 is adjusted according to the external temperature. The sodium chloride is operated through the injection nozzle 103 when the tower body 10 is operated in a low winter temperature. The injection nozzle 103 is frozen due to the water to be sprayed or broken, or the tower-shaped body 10 has a high possibility of failure, so it is input. The input amount of the sodium chloride may be put in a proper amount in the season when the temperature is low, while operating the tower body 10 by adding a very small or very small amount in the season when the temperature is high.

In addition, the fungicide may be added to the water introduced into the storage tank 160 to remove viruses contained in the air, and various types of additives may be added to the tower body 10 to suit the purpose. For example, plant extracts or flavors are added to make it feel fine but refreshing in the forest.

Referring to Figure 3 in detail,

Horizontal body 20 is an embodiment of the fine dust removal and sterilization system using the salt water of the present invention, the horizontal body 20 is through the suction fan 110 in the front unlike the top body 10 of FIG. Air is sucked in and passes through the injection nozzle 103 to purify the air is discharged through the outlet 120 formed on the side of the horizontal body (20).

The horizontal body 20 forms a suction fan 110 and a sensing sensor 115 on the front surface and a spray nozzle 103 on the inner upper end thereof, and the spray nozzle 103 is pumped using a pipe 104. It is connected to the 105 and the storage tank 160. The outlet 120 is formed on the side of the horizontal body 20, the outlet 120 and the outlet sensor 125 is formed. On the rear surface of the horizontal body 20, the filter medium screen 102 and the perforated plate screen 101 are continuously formed, and the fine dust filtered by the drain discharge pipe 135 is discharged.

Referring to Figure 4 in detail,

The indoor body 30 may be installed in the interior of a building as one embodiment of the fine dust removal and sterilization system using the salt water of the present invention. The indoor main body 30 forms a suction fan 110 and a detection sensor 115 on the outer wall of the building or the top of the building, and the perforated plate screen 101 and 2 as the inner side of the tower main body 10 of FIG. 1. The filter material screen 102 is composed of three to three, and the upper end of the injection nozzle 103 is configured. The rear of the filter medium screen 102 is further configured to generate a heat generating unit 900 to prevent the inside of the indoor body 30 is frozen by the water sprayed in the winter when the temperature is low. The outlet 120 and the outlet sensor 125 are formed on the rear surface of the indoor body 30, and the humidity sensor 128 is further formed to take humidity in consideration of the place where the indoor body 30 is installed. To control. The drain discharge pipe 135 is formed at the lower end of the indoor body 30 to discharge the filtered fine dust, and the like by adding a drain filtration screen 130 to the inside to discharge the pollutants discharged through the drain discharge pipe 135 Cleanse

Referring to Figure 5 in detail,

Road-type body 40 is an embodiment of the fine dust removal and sterilization system using the salt water of the present invention road-type body 40 is a structure that can be formed in the basement of the road suction fan 110 and the outlet 120 Is formed on the ground, the storage tank 160, the pump 105, the drain discharge pipe 135 and the drain filtration screen 130, the perforated plate screen 101 and the filter medium screen 102 formed inside the drain discharge pipe 135 ) And injection nozzles 103 are formed underground.

Referring to Figure 6 in detail,

Pagora-type body 50 is an embodiment of the fine dust removal and sterilization system using the salt water of the present invention Pagora-type body 50 is a roof-type structure to be installed in the park or downtown as a photovoltaic power generation on the top The water supply pipe 145, the drain discharge pipe 135, and the drain of the drain discharge pipe 135 are formed in the column portions formed on the both sides of the pagora-shaped main body 50 by forming the portion 180 and the rainwater inflow portion 150. The filtration screen 130 is formed.

The perforated plate screen 101 and the filter medium screen 102 are formed on the lower side of the roof formed on the upper portion of the pagora-type body 50 and the suction hole 110 and the outlet 120.

As described above, the fine dust removal and sterilization system using the salt water of the present invention can be configured by applying to various types of structures such as tower type, horizontal type, indoor type, road type, pagora type, and the like. It can be installed in various places so that it can cope with fine dust or yellow dust from winter to spring effectively, and can wash or supply fine dust using rainwater and sunlight to complete independent and eco-friendly fine dust removal and sterilization system. can do.

In the present invention, the above embodiment is an example, and the present invention is not limited thereto. Anything that has substantially the same configuration and achieves the same effect as the technical idea described in the claims of the present invention is included in the technical scope of the present invention.

10. Top Body
20. Horizontal Body
30. Indoor body
40. Road type body
50. Pagora type body
101. Perforated Plate Screen
102. Filter media screen
103. Spray Nozzle
104. Piping
105. Pump
110. Suction Fan
115. Sensor
120. Outlet
125. Outlet Detection Sensor
128. Humidity Sensor
130. Drain Filtration Screen
135. Drain discharge pipe
140. Input section
145. Water pipe
150. Rainwater Inlet
160. Storage Tank
170. Control Unit
180. Solar Power Generation Department
210. Pillar
250. The Bench
700. Ground
800. Stop
900. Heat generator

Claims (5)

In the tower body 10 constituting the fine dust removal system in the form of a tower that sucks air containing fine dust to purify from the inside to discharge clean air to the outside,
On one side of the outer front of the tower body 10 is formed a suction fan 110 composed of a plurality of suction air to the inside including the fine dust, the outer side of the top body 10, the outer fine dust Forming a sensing sensor 115 for sensing, forming a perforated plate screen 101 formed by drilling a plurality of holes on the inner front of the tower body 10, the pipe 104 for moving the salt water and the pipe The injection nozzle 103 for spraying the salt water moved along the 104 to the inside of the columnar body 10 is formed in the upper portion, and the pipe 104 is formed at the lower end of the columnar body 10. A pump 105 is formed on a side surface of the storage tank 160 connected to the storage tank 160 and stores the salt water to move the salt water inside the storage tank 160 to the pipe 104, and the tower body 10. The inner back of the filter) consists of two to three filter medium 102 is formed, and on one side of the outer side of the tower body 10 is formed an outlet 120 consisting of a plurality of discharged purified air to the outside, one side of the outer side of the tower body 10 outside An outlet detection sensor 125 is formed to detect the fine dust of the storage tank, and an input unit 140 is formed on the upper portion of the storage tank 160 to store and inject sodium chloride, a disinfectant and an additive, and the input unit 140. A drain filtration screen 130 is formed on the upper part of the water to purify the salt water, and the drain filtration screen 130 is connected to the drain discharge pipe 135 to discharge the pollutants, and the tower body 10 is formed. A solar power generation unit 180 is formed on the outer side of the tower body 10, and a rainwater inflow unit 150 is formed on the outer side of the tower body 10 to be connected to the storage tank 160. Forming control unit 170 to form a tower Fine dust removal and sterilization system using a number of salts, which is characterized in that the control (10). The method according to claim 1,
The control unit 170 is capable of controlling the tower body 10 and fine dust removal and sterilization system using salt water, characterized in that can be controlled remotely using a wired or wireless communication at a distance. The method according to claim 1,
The perforated plate screen 101 is formed by perforating a plurality of holes in the range of 0.5 to 5mm in diameter, the filter medium screen 102 is any one or more of activated carbon or metal filter or fiber filter or wood chips or ceramic, zeolite or sand Fine dust removal and sterilization system using a salt water, characterized in that for collecting fine dust. The method according to claim 1,
Fine dust using salt water, characterized in that the storage tank 160 is further connected to the water supply pipe 145 and the rainwater inlet 150 to provide a salt water sprayed through the injection nozzle (103). Removal and sterilization system. The method according to claim 1,
The amount of sodium chloride introduced into the storage tank 160 from the input unit 140 is fine dust removal and sterilization system using a salt water, characterized in that it is adjusted according to the external temperature.

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