Principle of wet heat exchange in high and low temperature alternating heat and humidity test chamber

The principle of wet heat exchange between high and low temperature alternating heat and humidity test chambers In the case of low temperature and high humidity, the amount of steam added is not only reduced due to the insufficient mixing of the added steam with the air or local condensation with the tank wall. And also emit heat to increase the temperature of the humid air inside the box; plus the above ε'> ε, so it is not an isothermal humidification process, the temperature inside the box will increase.

Steam humidification is divided into open type and closed type by electric humidification. The open type responsiveness is slow, and there is often hysteresis, so the humidity fluctuates greatly, but the structure is simple and reliable. The closed steam pressure is greater than atmospheric pressure, between 0.1 and 0.3 MPa, without hysteresis, but it needs to be equipped with a pressure reducing valve, a solenoid valve, a drain pipe, etc. The structure is complicated and is mostly used in a large artificial climate chamber. The open type is mostly used in small and medium-sized wet heat boxes.

The principle of heat and moisture exchange in direct contact between air and water:

When the air passes through the open water surface, it undergoes heat and moisture exchange with the water surface. Depending on the water temperature, only sensible heat exchange may occur; there may be both sensible heat exchange and wet exchange, as well as latent heat exchange. The sensible heat exchange is a temperature difference between air and water, which is caused by heat conduction, convection and radiation, and latent heat exchange is the result of evaporation (or condensation) of water vapor in the air to absorb (or release) latent heat of vaporization. The total heat exchange amount is the algebraic sum of the sensible heat exchange amount and the latent heat exchange amount.

When the air is in direct contact with the water surface, close to the water surface, due to the irregular movement of water molecules, a saturated air boundary layer with a temperature equal to the water surface temperature is formed, and the concentration of water vapor molecules or the water vapor pressure depends on the boundary layer. Saturated air temperature.

If the temperature of the boundary layer is higher than the temperature of the air above it, the boundary layer will transfer heat to the air; otherwise, the air will transfer heat to the boundary layer. If the concentration of water vapor molecules in the boundary layer is greater than the concentration of water vapor molecules on the air (ie, the partial pressure of water vapor in the boundary layer is greater than the partial pressure of water vapor in the air), the number of water vapor molecules in the air will increase; otherwise, it will decrease. . The former is called "evaporation" and the latter is called "condensation". During the evaporation process, the reduced water vapor molecules in the boundary layer are replenished by water molecules that jump out of the water surface; during the condensation process, too much water vapor molecules in the boundary layer will return to the water surface.

It can be seen that the sensible heat exchange between air and water depends on the temperature difference between the boundary layer and the air above it, and the wet exchange and the resulting latent heat exchange depend on the concentration difference or fraction of water vapor molecules between the two. Pressure difference.

The damp heat principle generates steam by electrically heating the water, and the steam enters the damp heat box through the spray pipe to humidify the air in the tank.

The steam above atmospheric pressure from the steam boiler is depressurized and then sprayed into a humid heat tank for humidification.

The airflow in the high and low temperature test chamber passes through the surface of the shallow water pan in the tank, and the temperature is equal to the saturated air boundary zone of the water surface temperature for wet heat exchange. When the concentration of steam molecules in the boundary zone is greater than the concentration of water vapor molecules in the flowing gas stream, it is humidified, and vice versa.

I. Product Description

TC-EM-1 is a polymeric emulsifier, which is a low molecular weight, high electropositive organic polymer. It has followed advantages:

1. Easy to use, do not need cooking. Reduce cooking equipment for solid starch and lower down technical condition fluctuation for cooking the starch.

2. Use current water to dilute and prepare, without heating.

3. Provide a strong positive charge to the system

4. High emulsion stability

 

II. Product Feature

Appearance

Red brown liquid

Solid content %

25. 50±0.5

Ionicity

Cation

PH value

3.50~4.50

Viscosity(mpa.s/25℃)

60.0

 AKD Emulsifier

III. Product Usage Safety Instruction:

TC-EM-1 may be stimulative to skin and eyes, and it is recommended to use gloves and protective glasses when use. If eye or skin comes into direct contact with this product, immediately rinse with plenty of water for at least 15 minutes. 

 

IV. Application

As a emulsifier and stabilizer of AKD,TC-EM-1 can provide a good stability of the emulsion. With the mechanical stirring, it can disperse AKD as required in the production process, which average particle diameter more than 80% can be less than 1.2 microns. It can also maintain a relative long time after the emulsification, and it has a certain electrical neutral to the slurry.

Please note, under high hardness, the hydrolysis rate of AKD emulsion will be greatly improved. So in order to reduce the rate of hydrolysis, the PH value of emulsified should be controlled between 4.5~5.0 by Citric Acid. TC-EM-1 has low PH value, which saves this part of the operation. 

For certain application, the usage of TC-EM-1 should also follow the operating instructions of our company.

 

V. Other Information

Package: 1000Kg /IBC barrel

Storage: in cool and dry place, avoid frozen and sunshine

Shelf life: 6 months.

AKD Emulsifier

AKD Emulsifier,Starch Based Emulsifier,AKD Emulsifying Agent,25% AKD Emulsifier

Shandong Tiancheng Chemical Co., Ltd. , https://www.tianchengchemical.com