SU1213321A1 - Method of controlling operation of sectional air cooler - Google Patents

Description

The invention relates to refrigeration engineering, in particular, to methods for regulating the operation of sectional air coolers, and can be used during the operation of air cooled and cooled, working under conditions of formation of a snow coat.

The purpose of the invention is to increase the continuous operation time before thawing.

The method of regulating the operation of the sectioned air cooler provides for supplying the coolant separately to each section, while the coolant flow increases from section to section and is determined by the formula

Q-,

N.

. - - t where Qn coolant flow through

e /

i-th section m / h |

0 - heat load on the air cooler, kW; - number of sections;

f 1 is the specific heat capacity of the coolant, k15t h / kg. hail; Pg is the specific gravity of the coolant, kg / m, the temperature difference of the coolant over the i and sections, and the installation of the flow rate begins with the first section in the course of the air movement.

In order to carry out the method, it is necessary to make a change and measure the flow rate of the coolant in the hygiene section, as well as measure the temperature of the coolant at the inlet and outlet of each section of the air cooler.

The installation of the coolant flow rate Q starts at the first day along the way.

air supply section with a value defined by the formula

,;

 N.C.p.it,

The setting of the coolant flow rates in the second and subsequent sections is made with the value of the reverse temperature distribution of the cold carrier, i.e., for any (i-f -) - E section of the air-cooler, the flow rate is determined from the ratio

g - l-1URutg

i

133212

The heat effect of the tunable section on the unsea tuned is excluded, since the flow setting starts with the first one in the air flow

5 sections.

Thus, the supply of coolant in the air cooler section according to the proposed method allows even frost distribution over the section 10 m and, thereby, increase the time of continuous drying before the air cooler thaws, which is confirmed by experimental studies

1.5 Example The air cooler was used for freezing with a different coolant flow rate according to the meter.

Air cooler is

20 ribbed apparatus. Air cooler fins - screw rolling edge. The location of the pipes chess. The external diameter of the pipe is 0.028 m, the diameter of the rib is 049 m, the thickness of the rib is 0.0008 m, the pitch between the fins is 0.0035 m. The air cooler is made in two sections, 9 rows of pipes in each section, with separate coolant feed to each section .

R 30 is used as the coolant. The air passes through the sections sequentially: first through the first, then through the second.

air parameters of air entering the air cooler: temperature 268 °}, moisture content 2.5 g / kg, consumption 490 m / h. The coolant temperature at the inlet is 240 K. During the mode, the air flow through the air cooler and other parameters of the air and coolant are kept constant ;. The parameters of the air leaving the apparatus: temperature 246 K, moisture content 0.4 g / kg.

The heat load on the air cooler is

(Bx- Bbixb4,74

kBr.

The required coolant flow through the first section is set to

q g 0.9.

The installation of the coolant flow rate in the second section is made with a value inversely proportional to the temperature difference of the charge agent.

in the first and second sections. ,one

2 ut s,

. 4 Q «- f 2.27%, f. .

Separate coolant supply with the thus selected flow rates for air cooler sections makes it possible to equalize the distribution in the sections, as evidenced by the same increase in the aerodynamic resistance of the sections. Continuous drying time 105 min.

To obtain comparative data, a mode with the same coolant flow rate was carried out in sections with the same parameters of air — at the inlet and outlet of the air-cooler.

1213321

Tests show that the first section is frozen faster than the second. At the same time, the aerodynamic resistance of the first section quickly increases, while the second section remains almost constant.

ten

15

The continuous operation time to defrost the air cooler in this mode is 60 minutes.

Thus, redistributing the coolant flow rate over the air cooler sections in a ratio inversely proportional to the temperature differential allows an increase in the time of continuous drying of the air before thawing, in this case most characteristic of a whole series of refrigeration systems in 1.7 times.

Claims (1)

METHOD FOR REGULATING THE WORK OF A SECTIONAL AIR COOLER, providing for the supply of a coolant in its section, characterized in that, in order to increase the time of continuous operation until thawing, the supply of coolant is carried out separately in each section, while the flow of coolant is increased from section to section and determined by the formula ^RN ' ^c r'Pr' R where Gr is the coolant flow rate through the ϊ-th section, m / h; - thermal load on the air cooler, kW; N is the number of sections; C ^ - specific heat of the coolant, kW · h / kg · deg; Pk is the specific gravity of the coolant, kg / m ^e ; the temperature difference of the coolant in the ί-th section, with the flow setting starting from the first section in the direction of air movement. >