HK1237401A

HK1237401A - Non-circulating pump refrigerant evaporator for absorption-type refrigeration unit

Info

Publication number: HK1237401A
Application number: HK17111455.6A
Authority: HK
Inventors: 邱伟; 杨如民; 武祥辉; 武维建; 刘彦武
Original assignee: 四川捷元科技有限公司
Filing date: 2017-11-08
Publication date: 2018-04-13

Description

Refrigerant evaporator of absorption refrigeration unit without circulating pump

Technical Field

The invention relates to the production field of lithium bromide absorption refrigerators, in particular to a small absorption refrigerator capable of being used as a refrigeration matrix independent unit and a refrigerant evaporator without a circulating pump in the small absorption refrigerator.

Background

The absorption refrigerator has the advantages of energy conservation, environmental protection and the like, is easy to use novel energy sources such as solar energy, industrial waste heat and the like, and is continuously developed. Miniaturization and family will be another trend after the application of the method to industrial fields.

The lithium bromide absorption refrigerator uses pure water as refrigerant, namely, the pure water is evaporated and absorbs heat under high vacuum environment to realize refrigeration function. The refrigerant vapor after heat absorption and evaporation is absorbed by the lithium bromide solution, transported, heated, regenerated and condensed, and then changed back to liquid state again, and then heat absorption and evaporation are carried out again, and refrigeration cycle is continuously carried out.

In the foregoing process, the device that achieves evaporative heat absorption is called an evaporator. Limited by the physicochemical properties of pure water, the evaporation temperature of the evaporator is usually set at about 5 ℃ for various refrigeration applications that meet the comfort requirements of the human body, which requires that the saturation pressure in the working chamber of the evaporator must be maintained at about 872 Pa. The pressure has high requirement on the air tightness of the refrigerator, the traditional absorption refrigerator ensures the sealing performance of high vacuum, so that most of the shell is made of a thick steel plate or a casting, and the heat exchange tube adopts a copper tube shell-and-tube heat exchange structure. The refrigerator is large in size, heavy in weight, and poor in corrosion resistance.

In addition, if a shell-and-tube heat exchanger is adopted to form a circulating pump-free refrigerant evaporator, the refrigerant generally flows in the shell pass; because the absolute evaporation capacity of the refrigerant is less, if the circulation quantity of the refrigerant water supplied by the shell side is equal to or only slightly more than the evaporation capacity of the refrigerant, along with the evaporation of the refrigerant, the refrigerant fluid is continuously reduced, so that the heat exchange tube cannot be fully wetted, and the phenomenon of 'dry spots' on the surface of the heat exchange tube is caused. The occurrence of dry spots greatly reduces the heat exchange coefficient of the heat exchanger. Therefore, in order to ensure sufficient humidification, a special refrigerant pump is often required to be arranged on the shell side, a refrigerant water body far greater than the actual evaporation amount is used, and refrigerant water which is not evaporated is continuously sprayed to the top of the evaporator from the bottom of the evaporator under the pumping of the refrigerant pump. The refrigerant pump increases the volume weight and the manufacturing cost of the refrigerating machine on one hand, and increases the operation cost on the other hand. Therefore, new improvements to the structure of the evaporator are urgently needed to meet the requirements of lighter weight, higher efficiency, more energy conservation and environmental protection.

Disclosure of Invention

The present invention is directed to solving the above problems, and one of the objectives of the present invention is to provide a circulation-pump-free refrigerant evaporator for an absorption refrigeration unit. The absorption refrigeration unit refers to a small lithium bromide absorption refrigerator with a complete refrigeration function, can be used independently, and also has the capacity of being combined and expanded into a large-scale refrigeration matrix.

The specific technical scheme is as follows:

a circulating pump-free refrigerant evaporator of an absorption refrigeration unit, comprising:

a plurality of rows of diversion trenches are arranged in an upper layer and a lower layer;

laying heat exchange tubes above the diversion trenches of each layer;

refrigerant water flows outside the heat exchange tube, and cold water flows inside the heat exchange tube;

the side wall of the diversion trench is provided with a plurality of drainage holes, so that the refrigerant water flows to the diversion trench at the lower layer to keep the refrigerant liquid to immerse the heat exchange tube.

Furthermore, the diversion trench is a rectangular shallow trench;

the side wall of the diversion trench facing the absorber on one side is a slope-type liquid-proof plate which is used for intercepting refrigerant water and only allowing refrigerant vapor to pass through.

Furthermore, the upper surface and the lower surface of the diversion trench are provided with support bars which form a certain included angle with the edge of the diversion trench, and the support bars are used for supporting an upper pipeline and a lower pipeline and changing the flowing direction of the refrigerant water in the diversion trench to generate turbulent flow.

Furthermore, the included angle between the supporting bars and the edge of the flow guide groove is 45-135 degrees.

Furthermore, the drain hole is arranged on the slope-type liquid isolating plate of the guide groove and is in an inverted triangle shape.

Furthermore, the drain holes on two adjacent layers of guide grooves are staggered with each other in the vertical direction.

Furthermore, the flow path of the refrigerant liquid forms a zigzag shape by the flow guide groove, and the zigzag flow guide groove is used for prolonging the heat exchange time of the refrigerant liquid and the heat exchange tube and generating turbulent flow.

Further, the diversion trench is made of engineering plastics; the heat exchange tube is made of stainless steel materials.

Further, under the combined action of the drainage hole and the diversion trench, after the stable working condition is achieved, the refrigerant water accumulated by the diversion trench just submerges the heat exchange tube;

the refrigerant water circulated from the regenerator and the condenser is added and supplemented to the first row of flow guide grooves of the evaporator, and the sum of the evaporation capacity of the refrigerant water in each row of flow guide grooves is exactly equal to the supplement capacity of the refrigerant water, so that the evaporator does not need to use a refrigerant circulating pump.

It is another object of the present invention to provide an absorption refrigeration unit comprising the above-mentioned circulating-pump-free refrigerant evaporator.

A third object of the present invention is to provide an absorption refrigeration matrix, which comprises a plurality of absorption refrigeration units;

the absorption refrigeration unit comprises the circulation-pump-free refrigerant evaporator of the absorption refrigeration unit as described above.

The invention has the beneficial effects that:

the refrigerant evaporator without the circulating pump adopts the heat exchange tubes with small diameter, thin tube wall and large density, and obtains larger heat exchange area in unit volume so as to meet the requirements of small volume and high heat exchange efficiency; the diversion guide grooves are arranged below each row of heat exchange tubes, so that refrigerant water is in contact with the heat exchange tubes in the diversion guide grooves for heat exchange, and refrigerant water flowing in the shell pass does not need to fill all the space of the shell pass and only needs to submerge the heat exchange tubes, so that the using amount of the refrigerant water is reduced; the liquid separation wall of the flow guide groove is provided with a V-shaped (inverted triangle) drainage hole, the deposition height of refrigerant fluid in the flow guide groove can be automatically adjusted according to the refrigerant flow, so that when the refrigeration load is small and the refrigerant flow is very small, the refrigerant water can uniformly infiltrate the heat exchange tube, the probability of 'dry spots' on the surface of the heat exchange tube is reduced, and the evaporation heat transfer coefficient is improved; meanwhile, the invention also adopts a new material and new process: expensive metal materials are abandoned in the evaporator, and engineering plastics with stronger corrosion resistance and easier forming are replaced; the heat exchange tube abandons expensive brass materials and is replaced by stainless steel materials with better corrosion resistance.

Drawings

FIG. 1 is a perspective view of the non-circulating pump refrigerant evaporator assembly of the present invention;

FIG. 2A is a cross-sectional view of a non-circulating pump refrigerant evaporator of the present invention;

FIG. 2B is an enlarged partial view of the circled area in FIG. 2A;

fig. 3 is a schematic view of a structure of a guide groove of the refrigerant evaporator without the circulation pump according to the present invention.

Wherein, the part structures or components are marked as follows:

an evaporator 101;

an absorber 102;

concentrated solution supply hole 103

A chilled water drain hole 104;

condenser bottom baffle 201

An orifice 202;

an evaporator heat exchange tube 203;

a diversion trench 204;

an absorber heat exchange tube 205;

a solution dispenser 206;

regenerator bottom baffle 207

An absorber solution outlet 208;

evaporator refrigerant water return 209;

a ramped liquid barrier 210;

the evaporator first discharge chute 301;

inverted triangular drain hole 302;

a ramp-type liquid barrier 303;

a support strip 304;

a heat exchange pipe 305;

an O-ring seal 306;

absorber draft trough 307.

Detailed Description

The accompanying drawings form a part of the specification; various embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that directional terms, such as "front," "rear," "upper," "lower," "left," "right," and the like, may be used herein to describe various example features and elements of the invention for purposes of illustration, but are only determined by the example orientations shown in the figures. Because the disclosed embodiments of the invention can be arranged in a variety of orientations, these directional terms are used for purposes of illustration only and are not to be construed as limiting. Wherever possible, the same or similar reference numbers used herein refer to the same or like parts.

as shown in fig. 1, the evaporator 101 and the absorber 102 are disposed in the same cavity; the refrigerant water required by the evaporator 101 is supplied from the refrigerant water orifice 104 provided at the bottom of the condenser above the evaporator, and the rich solution required by the absorber 102 is supplied from the rich solution supply hole 103 provided at the bottom of the regenerator above the evaporator.

Fig. 2A is a sectional view of a refrigerant evaporator without a circulation pump according to the present invention, and fig. 2B is a partially enlarged view of a circular region in fig. 2A.

As shown in fig. 2A and 2B, the heat exchange tube of the present invention has a compact layout, and has a small diameter, a thin wall, and a high density. As an embodiment, the evaporator 101 is a tube bundle array with 15 tubes per row and 36 tubes per column symmetrically and uniformly arranged by the heat exchange tubes 203 with the nominal outer diameter of 3 mm; in the horizontal direction, the center distance between every two adjacent heat exchange tubes is 3.5-4.5 mm; in the vertical direction, the center distance between every two adjacent heat exchange tubes is 6.5-7.5 mm; the fluid flowing in the pipe is cold water; the fluid flowing outside the pipe is chilled water. The design makes the evaporator 101 of the invention in fact a compact shell-and-tube heat exchange structure with a large heat transfer area to volume ratio.

In the evaporator 101, two rows of heat exchange tubes 203 adjacent up and down are separated by a diversion trench 204. In 36 rows of heat exchange tube bundles, there are 36 guide grooves in total. Two adjacent guide grooves 204 and the surrounding heat exchange tube 203 form a shell-and-tube heat exchanger; therefore, the evaporator 101 is actually formed by coupling 36 shell-and-tube heat exchangers. Each guide groove 204 is manufactured by precision injection molding, and the contact surface of the guide groove 204 and the heat exchange tube 203 is sealed by an O-ring seal 306 (see fig. 3) to ensure air tightness and water tightness.

In the initial state, chilled water accumulates on the bottom baffle 201 of the condenser; the chilled water throttled down and depressurized through orifice 202 in bottom partition 201 flows into the first lead-in channel in internal channel 204 of evaporator 101 (see fig. 1). By reasonably designing the drain holes 302 (see fig. 3) on the diversion trench 204, refrigerant water is accumulated in the first row diversion trench 204 to just submerge the first row of heat exchange tubes in the heat exchange tube bundle 203; then, the refrigerant water flows through the following discharge channels in the diversion channel 204 in sequence by the drain hole 302.

In each row of flow guide grooves, the refrigerant water exchanges heat with cold water flowing in the tube pass of the heat exchange tube 203, part of the refrigerant water absorbs heat and is evaporated into refrigerant vapor, and meanwhile, the temperature of the cold water in the tube pass of the heat exchange tube 203 is reduced; the refrigerant water that is not vaporized in the guiding gutter 204 returns to the absorber through the return hole 209 at the bottom of the evaporator 101 under the action of gravity. The refrigerant vapor evaporated in the evaporator channels flows through the sloped liquid barriers 210 to the absorber 205 where it is absorbed by the solution distributed from the solution distributor 206.

The entire process of refrigerant water from orifice 202, to evaporator 205, and back to the absorber from return orifice 209 is accomplished by gravity. And the refrigerant water in the 36 diversion trenches and the heat exchange tube perform immersion type heat exchange, when the refrigerant water works in a stable state under a rated refrigeration working condition, the refrigerant water supplied from the throttling hole 202 passes through the first drainage diversion trench and is completely evaporated when reaching the last drainage diversion trench, and a circulating pump is not needed.

FIG. 3 is a schematic view of a structure of a flow guide groove of the refrigerant evaporator without the circulation pump according to the present invention;

fig. 3 shows the first three rows of launders in the launder set 204 of fig. 2. First row diversion trench 301 is a rectangular diversion trench and is located below heat exchange tube bundle 305. The two sides of the bottom of the guide groove 301 are provided with support bars 304 which form an included angle of 45-135 degrees with the edge of the guide groove 301. The support bars 304 serve to support the heat exchange pipes 305, and also to change the flow direction of the refrigerant water flowing in the guide grooves 301 and generate turbulence. The support bars 304 are used for supporting the heat exchange tubes 305 and are used as a flow guide device for the refrigerant water, so that the vacuum pressure is transmitted, the refrigerant water is guided to flow through the heat exchange tubes 305 along a curve path, the flow distance of the refrigerant water is increased, and the turbulent flow effect is generated.

A slope-type liquid-isolating plate 303 is arranged at the left edge of the diversion trench 301 and is used for intercepting liquid drops possibly entrained in the refrigerant vapor. 4 drain holes 302 are arranged on the slope of one side of the liquid separation plate 303 facing the diversion trench 301, and are used for uniformly distributing the refrigerant water in the diversion trench 301 to the diversion trench on the lower layer. The flow guide groove 301 guides and distributes the accumulated coolant water, so that the coolant water uniformly flows through each row of heat exchange tubes, the splashing phenomenon caused by free fall of the coolant water is effectively prevented, and the heat of the cold water flowing in the tube pass of each heat exchange tube 305 is better absorbed when the coolant water flows through each row of heat exchange tubes 305 layer by layer from top to bottom.

The drain hole 302 is an inverted triangle, and the drain hole 302 can automatically adjust the deposition height of the refrigerant water in the diversion trench 301 according to the refrigerant flow: when the flow rate of the refrigerant water is large, the liquid height reaches the upper part of the drain hole 302, and the liquid discharge amount is increased; when the flow rate of the refrigerant water is small, the liquid level is low, and the liquid discharge amount is reduced through the lower part of the drain hole 302. So that the refrigerant water can uniformly infiltrate the heat exchange tube 305 when the refrigeration load is small and the refrigerant flow is small, the chance of 'dry spots' on the surface of the heat exchange tube 305 is reduced, and the heat transfer coefficient is improved.

In all channels after the first drainage channel 301, the same drainage holes 302 are provided, but the positions of the drainage holes are staggered layer by layer, and the method is as follows: the upper layer of drain holes and the adjacent lower layer of drain holes can not be communicated, and the refrigerant water from the upper layer of drain holes can not directly drop to the lower layer of drain holes, but firstly drops to the slope-type liquid isolating plate 303, and then flows through the heat exchange tube bundle 305 in the diversion trench 301 under the combined action of the liquid isolating plate 303 and the supporting bars 304; after exchanging heat with the fluid on the tube side of heat exchange tube bundle 305, it passes through 302 and drops to the next layer. The design enables the flow path of the refrigerant water to form a zigzag shape, and the contact heat exchange time of the refrigerant water and the surface of the heat exchange tube is greatly increased; the flow path of the refrigerant water is interrupted for many times, so that the flow turbulence effect is increased, and the heat exchange efficiency is improved.

Although the present invention will be described with reference to the particular embodiments shown in the drawings, it is to be understood that the pumparless refrigerant evaporator and absorption refrigeration unit and refrigeration matrix of the present invention can take many forms without departing from the spirit, scope and context of the present teachings, such as changes in the shape of the baffle slots, changes in the size of the vent holes, and the like. Those of ordinary skill in the art will also appreciate that there are different ways of varying the parameters, dimensions, and so forth of the disclosed embodiments of the invention that fall within the spirit and scope of the invention and the appended claims.

Claims

1. The utility model provides an absorption refrigeration unit does not have circulating pump refrigerant evaporimeter which characterized in that includes:

laying heat exchange tubes above the diversion trenches of each layer;

2. The absorption refrigeration unit circulating-pump-free refrigerant evaporator as recited in claim 1, wherein:

the diversion trench is a rectangular shallow trench;

3. The absorption refrigeration unit circulating-pump-free refrigerant evaporator as recited in claim 1, wherein:

and the upper surface and the lower surface of the diversion trench are provided with support bars which form a certain included angle with the edge of the diversion trench, and the support bars are used for supporting an upper pipeline and a lower pipeline and changing the flowing direction of refrigerant water in the diversion trench to generate turbulent flow.

4. The circulating-pump-free refrigerant evaporator of an absorption refrigeration unit as claimed in claim 3, wherein:

the included angle between the supporting bars and the edge of the flow guide groove is 45-135 degrees.

5. The absorption refrigeration unit circulating-pump-free refrigerant evaporator as recited in claim 1, wherein:

the drainage hole is arranged on the slope-type liquid separation plate of the diversion trench and is in an inverted triangle shape.

6. The absorption refrigeration unit circulating-pump-free refrigerant evaporator as recited in claim 5, wherein:

the discharge holes on two adjacent layers of guide grooves are staggered with each other in the vertical direction.

7. The absorption refrigeration unit circulating-pump-free refrigerant evaporator as recited in claim 1, wherein:

the flow guide groove enables the flow path of the refrigerant liquid to form a zigzag shape, and is used for prolonging the heat exchange time of the refrigerant liquid and the heat exchange tube and generating turbulent flow.

8. The absorption refrigeration unit circulating-pump-free refrigerant evaporator as recited in claim 1, wherein:

the diversion trench is made of engineering plastics; the heat exchange tube is made of stainless steel materials.

9. The absorption refrigeration unit circulating-pump-free refrigerant evaporator as recited in claims 1 to 8, wherein:

the combined action of the drainage hole and the diversion trench ensures that refrigerant water accumulated in the diversion trench just submerges the heat exchange tube after entering a stable working condition;

10. An absorption refrigeration unit, characterized by:

a recirculating pump-free refrigerant evaporator comprising the absorption refrigeration unit of any of claims 1-9.

11. An absorption refrigeration matrix, characterized by:

comprising a plurality of absorption refrigeration units;

the absorption refrigeration unit comprises the circulating pump-free refrigerant evaporator of any one of claims 1-9.