UA66218A - A process for preparation of sweet water from air - Google Patents

Abstract

A process for preparation of sweet water from air consists in that a given amount of water being incorporated into the heat-exchanger; temperature of water is lower than the temperature of air surrounding the heat-exchanger, and the heat-exchanger is kept with water in these conditions with a simultaneous selection of condensed sweet water.

Description

The invention relates to a method of producing fresh water from air by condensation.

Many methods of water production by desalination of seawater are known, in particular: chemical, electrochemical, ultrafiltration, freezing, etc.

The distillation method of water production (thermal evaporation) is also known. Seawater is heated to boiling, the steam that is formed is collected and condensed. Water can be evaporated both during boiling and without boiling. In the latter case, the water is heated at a pressure greater than the pressure in the evaporation chamber, where the water is supplied. As a result of the fact that the water temperature exceeds the saturation temperature corresponding to the pressure in the evaporation chamber, part of the water that entered the chamber turns into steam, which condenses into distillate (see Bogomolnyi A.E.

Leningrad, "Shipbuilding", 1980, pp. 290-292).

But, both in this method and in the other methods mentioned above, water is used as a working medium, from which steam is produced, and it (steam) is subjected to condensation. This leads to excessive energy costs for: pumping offshore seawater; heating water to boiling, or heating water below the boiling temperature while creating rarefaction.

In connection with the above, the declared method of fresh water production coincides with the known method only in terms of the principle (way) of the solution to the given problem, namely the use of condensation. But in a known method, distilled water, i.e. distillate, is produced by condensation.

Based on the above, the only thing common to the claimed and known method is that both solutions use a physical phenomenon - condensation.

But the physical phenomenon cannot be considered as a sign (an operation performed during the execution of the method). In addition, the known method obtains distillate from sea water, and the claimed method refers to the method of producing fresh driver from air.

In this connection, the applicant believes that the claimed method does not have a prototype.

The invention is based on the task of developing a method of producing fresh water from the air, in which, due to the proposed sequence of operations, a significant reduction in energy costs for obtaining fresh water from the air is ensured.

The problem is solved in the method of producing fresh water from the air by placing a given amount of water in the heat exchanger, the temperature of which is lower than the temperature of the air surrounding the heat exchanger and maintaining the heat exchanger with water in these conditions with the simultaneous withdrawal of condensed fresh water.

The novelty of the invention lies in the sequence of proposed operations.

The amount of water placed in the heat exchanger depends on the internal volume of the heat exchanger, which is used in each specific case.

The difference between the temperature of the water that is placed in the heat exchanger and the temperature of the air surrounding the heat exchanger with water is related to the conditions in which fresh water is produced and it affects the amount of fresh driver that is obtained per unit of time. In particular, the lower the temperature of the water placed in the heat exchanger (ideally "4"C) and the higher the temperature of the air surrounding the heat exchanger with water (28-32"C in the conditions of Southern Ukraine in summer) and the relative humidity of the air, the more will be produced of fresh water for a certain period of time. vice versa. Therefore, it is impractical to state the gradient of the temperature difference of the water in the heat exchanger and the air surrounding the heat exchanger with water.

Example 1.

The heat exchanger, made in the form of a pipe with a diameter of 1 m and a length of 1 m, contained water from an artesian well, which had a temperature of 6 °C. The temperature of the air around the heat exchanger with water was 32 °C, the wind speed was 1 m/s, and the relative humidity of the air was 8095.

During 4 hours, fresh water appeared on the walls of the heat exchanger in the form of condensate, which was constantly collected in a glass cylinder. 13 liters of condensate was collected in 4 hours. During this time, the water temperature in the heat exchanger rose to 22°C, i.e. the water heated up to 167°C.

To confirm the economic and energetic feasibility of this method, thermophysical calculations were carried out. All thermophysical calculations were carried out according to the formulas given in the book "Basic formulas and data on heat exchange for engineers", Wang, H., M.. "Atomnzdat", 1979.

In the calculations, the same parameters of the environment and the same temperature of cold water, the same dimensions and geometric shape of the heat exchanger were left.

According to diagram 4 of humid air, which graphically displays the dependence between the main physical parameters of air, the moisture content of air under these conditions was 9 -2407:10 kg/kg of dry air.

The amount of compressive heat during convective heat exchange was found using the formula x and where Mu-b.ve". NusseltaubFfez dimensional value); x - thermal conductivity coefficient, m/s;

E - surface area of the heat exchanger, m; p st FOR the difference between the temperature of the air and the wall of the heat exchanger;

Since AE is constantly changing, a definite integral with integration limits of -2670 and А т10"С was used to determine o. That is, the integration limit is the temperature difference at the beginning and end of the experiment. x is a characteristic size, which for this geometric shape of the heat exchanger is equal to O -4 M;

WITH ; "t - constants for a given type of flow and geometry of the heat exchanger;

where- M X what is the Reynolds number (dimensionless value); manifest

WITH

P - air density, M';

M. air speed; carry

K - dynamic air viscosity, M'.

Using table interpolation. 5 we have: Tu

P -1.1595 comma 18922. 105kg/m-s, A -0.02662 MK,

Ve- -08B0020 - 5820199

Then 19922-10

From tabivuzylvayemkogovo. 08167 "814.

Guide 9050208 "p8201.9995 t:35795783. 2 -131547.4-(6 - 3788KW 2 lo

The volume of water flowing in the heat exchanger is:

Mv - Ua loze Zv 1-7854,

Taking Pv -1000kg/m3, we have the mass of water Ma 785, Akg.

To heat this mass of water to 16"C, it is necessary to spend about -785.4:4.187:16-52615.5168Kj. Determine the mass of air that is heated in water;

M go yaie: d In lov vni a ru

R kg, where A is the Gretzian number (dimensionless value); Ri - Prandya number (dimensionless quantity).

From the table 5 we have: 58 tiFOV,Zzhukg: k - heat capacity of air; Рг -0.707, с» -ЗВ- - - - - t 95820199.0.707 - 32318.27296

Then the mass is 27296.002062 m, - ШЕСЕВое о вBBAG 10063 s

As a result of heat exchange, the enthalpy of air decreases by DI З,788:0,855-4 4З3KJ/kg.

Id and diagram found 7 -93.814Kj/kg. Then 2 -93,814-4,43-89,384 Kj/kg, while the moisture content of the air was 9,2297.105KG/K dry. district Thus, as a result of heat exchange, the condensation amounted to 2407 105-2297 10 5 kg/kge 110 10 5 kg/kg dry. district Next, energy calculations for water supply were carried out. Why was the mass-produced pump OMPV 250-10.5 used for which supply: Me -250 m3/g, H -09.5m - pressure,

R 1Я1kWteg electric drive power. Relative to ikW:h of power M 22.127m3/h. This volume of water fills the heat exchanger with a length of 22.121:0.7854-28.937 m. Then the total amount of air involved in heat exchange is: "7 -0.855:28.937-24.741Kkg/s.

The time required to heat 785.4 kg of water to 167C was determined. t 752615,517/3788-13890s.

The total mass of condensate with energy consumption in the amount of uKW/g is: VC. -24,741.13890-110-10-5e378,017 kg.

The essence of the proposed method is that water from seas, oceans, rivers, lakes, reservoirs, underground and groundwater is used as a coolant for heat exchangers.

World practice provides many examples of technical solutions to the problem of fresh water. Searches in this direction are ongoing and have gained particular intensity in recent decades.

RESE Corporation (Riapeiagu Epdipeypypud Stor Eapy) offers various modifications of water desalination plants with the production of 41 liters of water per 1kW/h.

A very interesting method of obtaining fresh water has been developed: Nemegeye o5toziv HO ipviaIIaiope, which in translation has the following meaning: reverse osmosis apparatus (reverse osmosis of humidification-dehumidification) (RO).

Total energy consumption: heat energy 5000 kcal/m3 of water; electric energy 5 7 7kW/m3 for brine.

Moreover, about 5,095 devices in the world work on this principle (according to their data).

Thus, the given calculations allow us to draw the following conclusions: the declared method has significant advantages in terms of economy compared to any existing method of fresh water production; the method is much simpler in hardware design; it does not require expensive equipment; the fresh water obtained in this way is suitable for consumption without any sanitary treatment, because the condensation of bacteria dangerous to humans (cholera, Botkin, etc.) in the air is incomparably lower than in any water used for desalination.

Claims (1)

The method of producing fresh water from air, which consists in placing a given amount of water in the heat exchanger, the temperature of which is lower than the temperature of the air surrounding the heat exchanger, and maintaining the heat exchanger with water in these conditions with simultaneous withdrawal from the condensed fresh water.