NL1024135C1 - Device specifically cools fluids by means of material transfer and convection, cooling process being enacted in two stages - Google Patents

Abstract

The device specifically cools fluids by means of material transfer and convection. The cooling process is enacted in two stages. In the first stage, the fluid is cooled with a cold pipe wall by convection. The material transfer takes place in the fliud film present on the pipe wall. The fluid film ensures that the contact time between fluid and gas notably increases, so that the efficiency of the cooling process is enhanced.

Description

Short indication:

Device that makes it difficult to do ole-specific ways of cooling liquids by means of dust transfer and convection

The invention has the feature (1) that it is a method for letting heat and dust transfer processes in liquids and crashes contain using null profiles, each of which has an airtight surface, as a result of which an openina is formed where they are put together. can flow through air and liquid. The tubes are equipped with a material that can hold a water film. A second feature (2) is that the fluid first flows through the tubes and is cooled by convection through the same fluid that previously flowed through the tube. When the liquid flows out of the tube, the liquid runs downwards along the IS outside of the tubes by means of gravity. The special layer applied to the tubes ensures that the fall speed is considerably reduced, so that the contact time between the liquid and the gas flowing past will increase considerably. If this liquid film is exposed to a gas characteristic (3), then depending on the temperature of the gas and liquid, evaporation or condensation. This will change the temperature of the liquid film and the gas.

It is known that a large number of different types of heat exchangers have been designed and made for these physical processes. In all these heat exchangers, a gas and liquid contact is established indirectly or directly. It is of the greatest importance that the liquid film of the contact surface is moistened as evenly as possible. The latter is attempted in all sorts of ingenious ways by spraying the liquid on the surface or allowing the liquid to flow down in a thin water film along the contact surface. A very big disadvantage here is that the liquid flow, partly under the influence of the type of contact material, is broken by the flowing gas flow, so-called dry spots are created. Moreover, in the event of a high liquid load, the flow-through opening of the contact package can be completely or partially blocked. These factors lead to a loss of return. The contact time between the liquid and the gas is very limited and is only one second at a fall height of 10 m.

Feature (4) with the invention is achieved that the liquid film on the contact surface cannot contain dry spots because the liquid overflows from the flat tubes at the top and flows downwards through the special layer along the other side of the tube. The surface becomes • .η? d13 5

I 2 I

I thereby evenly moistened so that the dust transfer process without I

I loss of return can occur. Characteristic (5) of the invention is the I

I contact time between the liquid and the gas generated by choosing the I

I length of the tube can be adjusted depending on the load and I

I 5 climate conditions the highest efficiency can be achieved. I

A sixth characteristic (6) is that the entire heat and dust transfer I

I. process takes place in more steps. I

I Step 1 The wetted material is exposed to the gas. By I

Due to the different vapor pressures, dust transfer will take place between the I

I gas and the liquid. This lowers the temperature of the gas and the I

I liquid film on the tube wall. This process continues until the vapor pressure I

I of the liquid and the vapor pressure of the gas are the same. The consequence of I

I this substance transfer is that the condition of the liquid and the gas is I

I 15 amended. I

I Step 2 The liquid film whose condition has changed ensures I

I that the temperature of the tube wall changes as a result of this I find by convection

I heat exchange takes place between the tube wall and the liquid

The invention of this process will be explained below with reference to a calculation I

An example and a figure of a process water cooler are further explained. I

FIG. 1 schematically shows the side view of the process water cooler. I

I With this process water cooler, water is cooled from 32 ° C to 22®C. The I

I flat tubes are closed together until a package is created through which I

I the liquid and the air can flow. The air is supplied by a fan I

I * 25 is blown through the package and thereby comes into contact with the water film that I

I is present on the package. The air flowing in cross stream through the package I

I flows, has a dry bulb temperature of 30 ° C and a wet bulb I

I temperature of 20 ° C. It is known from measurements that the substance transfer I

I coefficient is 1450 kJ.m'2, which is 2.5 times greater than the I

I heat transfer coefficient. We use I for the sake of calculation

that the average water film temperature on the tube wall is 25 ° C. I

The water vapor pressure thereof is 0.0316 kg / cm 2. The relative I

humidity of the air with a dry bulb temp of 30 ° C and a Nattebol I

temp of 20 ° c is 40%. The vapor pressure of the water vapor in that air is I

35, therefore, 40% x 0.0433 * 0.01732 kg / cm 2

The difference is 0.0316-0.01732. 0.0143 kg / cm 2

We consider a contact surface of 1 m2. This surface becomes I

flowed through with air whereby dust transfer takes place. This cools I

the water film on the rotor to 20 ° C. The original temperature was I

40 25 ° c, which gives a temperature drop of 30-20 ° 10®C. The amount of I

water that can have one m2 of contact surface under the assumed conditions I

1024135 I

3 discharge amounts: dust transfer coefficient x evaporation heat of water x contact surface x difference in vapor pressure. This corresponds to 1450 x 2600 x 1 x 0.0143 kg / cma = 54,000 kj / hr. The total evaporation capacity of the process water cooler is determined by the S size of the total contact surface of the cooling package, the vapor pressure difference between the water on the water film and the water vapor in the air.

10 1024135

Claims (3)

2. The heat and dust transfer process according to claim 1, characterized in that the liquid first flows through the tubes and is cooled by means of convection II through the same liquid that on the other side II of the tube as a water film. falls down. The liquid film is exposed to gas (s) where heat and dust transfer can take place due to the difference of the I-vapor stresses of the liquid vapor and the vapor pressure of the liquid I-IS film on the contact material. I The heat and dust transfer process according to claims 1 and 2, characterized in that the efficiency of the process can be influenced by controlling the II duration of the contact time of the contact time between the liquid and the gas II on the contact surface . 4. By the uniform wetting of the contact surface that is obtained by liquid film flowing over the pipe wall, the contact surface is optimally utilized, so that a high efficiency can be achieved. I 5. The cooling process takes place in two separate steps. The first step is to evaporate the water on the outer wall of the flat tube. The second step exchanges heat by means of convection with II the cooled tube pipe II which is mentioned by the evaporation process mentioned in the first step. 6. With the aforementioned heat transfer process and basic II configuration of the materials, multiple dust transfer and convection II processes are carried out such as: Cooling process water, cooling II of Air, absorbing gases, desalinating seawater. I