CN111208168A

CN111208168A - Method for capturing tidal surge heat exchange phenomenon of porous medium soil body

Info

Publication number: CN111208168A
Application number: CN202010112944.3A
Authority: CN
Inventors: 王丽慧; 左沪; 刘鹏飞
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2020-02-24
Filing date: 2020-02-24
Publication date: 2020-05-29
Anticipated expiration: 2040-02-24
Also published as: CN111208168B

Abstract

The invention relates to a method for catching the tidal surge heat exchange phenomenon of a porous medium soil body, which comprises the following steps of firstly adding water into the porous medium soil body to moisten the porous medium soil body until liquid water is filled in pores; the method can fill the blank of research on soil body tidal surge heat exchange and reveal the soil phase change heat exchange characteristic to a certain extent, and the method relates to fewer objects, is simple and convenient in experimental method, only needs to measure whether the heat flow density value has step mutation or not, and is easy to observe and judge.

Description

Method for capturing tidal surge heat exchange phenomenon of porous medium soil body

Technical Field

The invention relates to a method for capturing a soil heat accumulation and release phenomenon, in particular to a method for capturing a tidal surge heat exchange phenomenon caused by phase change condensation and large heat release due to rapid temperature drop of gas in pores of a porous medium.

Background

At present, the research on the phase change condensation heat exchange of the soil body is very little. The only relevant studies exist in the study of the condensation phenomenon of the building envelope, and the students represented by the university of Hunan and the university of Shenyang construction reveal the mechanism of the occurrence of the condensation phenomenon of the ground building envelope from the temperature decrease and the change of the water vapor partial pressure. In addition, Shanghai university clearly indicates that the current research on the latent heat effect of soil water vapor is quite lack, and the sufficient understanding on the phase change heat exchange characteristic of soil is lacked. Therefore, a method and a result for monitoring and capturing the heat flow density of the wall surface of the station hall layer of the subway station in a long term are needed to be provided, and an important theoretical basis is provided for explaining that the temperature of the underground space such as the subway station hall in autumn and winter with obvious outdoor temperature drop is kept relatively stable.

Disclosure of Invention

The invention provides a method for capturing a porous medium soil body tidal surge heat exchange phenomenon, which is used for filling the blank of the research on the soil body tidal surge heat exchange in an underground space and revealing the phase change heat exchange characteristic of soil to a certain extent; the method has fewer related objects and is simple and convenient in experimental method, only the heat flow density value is required to be measured whether step mutation occurs, and observation and judgment are easy.

In order to achieve the purpose, the technical scheme of the invention is as follows: a method for capturing the tidal surge heat exchange phenomenon of a porous medium soil body is characterized by comprising the following steps:

step 1: adding water into the porous medium soil body to moisten the porous medium soil body until liquid water is filled in pores;

step 2: heating the soil body to enable water in the soil body to exist in soil body pores in a vapor gas form;

and step 3: arranging a heat flow densimeter on the surface of the soil body, and then suddenly reducing the air around the soil body, or the surface of the soil body, or the overall temperature of the soil body to be below the saturation temperature corresponding to the partial pressure of water vapor in the soil body;

and 4, step 4: when the heat flow density value displayed by the heat flow densitometer arranged on the surface of the soil body has a step surge phenomenon, the phenomenon of soil body surge heat exchange of the characterization porous medium occurs.

Further, in the step 1, water is added into the porous medium soil body to moisten the porous medium soil body until liquid water is filled in pores, wherein the porous medium is one of the soil body, rocks, and roots and stems of plants.

Further, in the step 2, the soil body is heated by being exposed to the sun or blowing hot air to the periphery of the soil body by using a fan heater, or the soil body is heated integrally.

Further, in the step 3, the air around the soil body is suddenly reduced to be below the saturation temperature corresponding to the water vapor partial pressure in the soil body, and the soil body is placed in a refrigerator or the air side contacted with the soil body is subjected to rapid temperature reduction treatment; the temperature reduction requirement is that the gas in the pores of the porous medium soil body reaches the saturation temperature under the corresponding water vapor partial pressure in a short time, so that the condensation phenomenon occurs, and a large amount of latent heat is released.

Compared with the prior art, the invention has the following beneficial effects:

the invention fills the blank of the research on the tidal surge heat exchange of the soil body in the underground space, and comprises the following steps:

1. the phase change heat exchange characteristic of the soil is revealed to a certain extent;

2. the invention provides a simpler and more convenient capturing method, which relates to fewer objects and is simple and convenient in experimental method, only needs to measure whether the heat flow density value has step mutation, and is easy to observe and judge;

3. the invention provides a method for capturing soil body tidal surge heat exchange, which has important reference value for subsequent phase change heat exchange researches such as soil body porous medium tidal surge and the like.

Drawings

FIG. 1 is a graph of outdoor air and platform air temperature over time;

FIG. 2 is a graph of the density value of heat flow on the wall surface of a soil body along with the change of time.

Detailed Description

The present invention will be further illustrated by the following examples and the accompanying drawings, and the methods of practicing the present invention include, but are not limited to, the following examples.

The invention discloses a method for capturing a tidal surge heat exchange phenomenon of a porous medium soil body, which comprises the following steps:

step 1: adding water into the porous medium soil body to moisten the porous medium soil body until liquid water is filled in pores; the porous medium is one of soil, rock, plant root and stem.

Step 2: the soil body is heated by exposing the soil body in the sun or blowing hot air to the periphery of the soil body by using a fan heater, or the soil body is integrally heated, so that the moisture in the soil body exists in the pores of the soil body in the form of vapor gas.

And step 3: arranging a heat flow densimeter on the surface of the soil body, then leading the air around the soil body, or leading the surface of the soil body, or leading the overall temperature of the soil body to be suddenly reduced to be lower than the saturation temperature corresponding to the partial pressure of water vapor in the soil body, and putting the soil body in a refrigerator or carrying out rapid temperature reduction treatment on the air side contacted with the soil body; the temperature reduction requirement is that the gas in the pores of the porous medium soil body reaches the saturation temperature under the corresponding water vapor partial pressure in a short time, so that the condensation phenomenon occurs, and a large amount of latent heat is released.

In this embodiment: to capture the known conditions of the soil mass tidal surge heat exchange embodiment: the experimental date is 2016, 1, 24 days, the weather is clear, the experimental site is a certain subway station with a number 11 Shanghai subway line, the station is provided with three entrances and exits, the wall temperature, the wall heat flux density and the air temperature are measured every two hours from 9:30 in the morning to 23:30 in the evening, the positions of the measuring points are described as the following measuring point 1 which is an outdoor air temperature measuring point, the

measuring points

2 and 3 are respectively positioned near the entrance and exit stairs of number 1, the measuring points 8 and 9 are respectively positioned near the entrance and exit stairs of number 2, the

measuring points

4, 5, 6, 7, 10, 11, 12, 13 and 14 are respectively positioned near the side wall layer of the subway station hall, the

measuring points

15 and 16 are positioned near the stairs between the station hall layer and the station layer, and the measuring point 17 is positioned near the station layer.

Step 1: according to geological exploration, the subway station is located 5m below the ground in the Shanghai, a large amount of underground water permeates around the soil body, and the requirement of the step 1 that the porous medium of the soil body contains water is met.

Step 2: the experiment is carried out in autumn and winter, and through the whole hot summer, the moisture in the soil body porous medium of the subway station surrounding rock shield exists in pores of the soil body porous medium in a gas form due to the effects of solar irradiation and summer outdoor temperature rise.

And step 3: continuously monitoring the parameter changes of heat flow density measuring

points

3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16 and 17 at intervals of 2 hours at multiple points on the wall surface of a soil body of the station, and suddenly reducing the outdoor air temperature measuring point to 14.8 ℃ (measured at 23:30 in the evening) from 19.2 ℃ (measured at 9:30 in the morning) to 14.8 ℃ (measured at 23:30 in the evening) due to the action of cold air on the day of testing, so that the air temperature in the station room suddenly reduces, and the condition of suddenly reducing the air temperature on the wall surface of the soil body is met;

and 4, step 4: from the measured value change diagram of the soil heat flow density (see fig. 2), it can be seen that at 21: the 30-hour heat flow density value has a step surge phenomenon (the number of digits of a single-digit meter per square meter), namely the phenomenon of soil mass tidal surge and heat exchange captured in the field actual measurement work of the subway station.

In addition, the rising of the temperature of the air side of the station hall after the test day 21:30 (see figure 1) can further verify that the rising of the temperature of the station hall comes from the heat release process of the rising of the heat flow density of the soil body of the surrounding rock, and the heat balance between the soil body and the air is embodied.

Claims

1. A method for capturing the tidal surge heat exchange phenomenon of a porous medium soil body is characterized by comprising the following steps:

2. The method for capturing the tidal surge heat exchange phenomenon of the porous medium soil body as claimed in claim 1, wherein the method comprises the following steps: in the step 1, water is added into a porous medium soil body to moisten the porous medium soil body until liquid water is filled in pores, wherein the porous medium is one of the soil body, rocks, and roots and stems of plants.

3. The method for capturing the tidal surge heat exchange phenomenon of the porous medium soil body as claimed in claim 1, wherein the method comprises the following steps: in the step 2, the soil body is heated by being exposed to the sun or blowing hot air to the periphery of the soil body by using a fan heater, or the soil body is integrally heated.

4. The method for capturing the tidal surge heat exchange phenomenon of the porous medium soil body as claimed in claim 1, wherein the method comprises the following steps: step 3, rapidly reducing the air around the soil body to be below the saturation temperature corresponding to the water vapor partial pressure in the soil body, and placing the soil body in a refrigerator or carrying out rapid temperature reduction treatment on the air side contacted with the soil body; the temperature reduction requirement is that the gas in the pores of the porous medium soil body reaches the saturation temperature under the corresponding water vapor partial pressure in a short time, so that the condensation phenomenon occurs, and a large amount of latent heat is released.