A kind of method for arranging of heat exchanger flow circuit and device thereof
One, technical field
The present invention relates to a kind of refrigeration plant and air-condition heat exchanger that uses single and mix refrigerant, particularly a kind of stream method for arranging and device thereof of heat exchanger.
Two, background technology
Past people more has been placed on energy on change fin type and the heat exchanger tube internal structure when improving the heat exchanger coefficient of heat transfer.The fin type develops into present corrugated plate, " X " type sheet etc. that cracks from original plain film, and the pipe inner structure develops into present two-dimentional screwed pipe from original light pipe, even the three-dimensional thread pipe.These measures have obvious effects to improving the coefficient of heat transfer.Minitype air conditioner heat exchanger (biexhaust pipe heat exchanger) now commonly used generally all adopts following several stream to arrange: " Z " font stream, stream is arranged " single two one is single ", " going with each other all the time " (advance in the middle of can being divided into according to the position of importing and exporting, the centre goes out, go out on enterprising and under go out under advancing) etc., these several arrangements cut both ways.Summary is got up, and the shortcoming of above-mentioned various method for arranging is: often only consider a problem from single viewpoint (as need to strengthen heat transfer), shortage is taken all factors into consideration, the thought of more utilizing a synergistic principle and waiting the hot-fluid layout.
Three, summary of the invention
The objective of the invention is to overcome the shortcoming of above-mentioned prior art, a kind of heat exchanger flow circuit method for arranging and device thereof that can improve heat exchange efficiency is provided.
For achieving the above object, the method that the present invention adopts is:
1) pure counter-flow arrangement
According to the thermal conduction study basic principle, the mean temperature difference maximum of adverse current under identical out temperature condition, the mean temperature difference minimum of following current is so under identical cold fluid and hot fluid temperature, counter-flow arrangement is better than following current and arranges that promptly the refrigerant flow direction is opposite with air-flow direction;
2) prevent reverse heat conduction in the fin
The import of cold-producing medium and outlet all are in an end of heat exchanger together, have the bigger temperature difference in the fin at this place, so adopt part to crack at the import and the port of export of cold-producing medium;
3) arrange the import and export of heat exchanger according to the phase of refrigerant
When heat exchanger was done the evaporimeter use, because the phase of import department's refrigerant of evaporimeter is a liquid phase, the phase in exit was a gaseous state, the import and the outlet of heat exchanger should be arranged on the upper end; When using as condenser, the exit refrigerant phase of condenser is liquid, and import department's phase is a gaseous state, and import and export should be arranged on the bottom of heat exchanger;
4) make heat exchanger local heat flux density near even
If the local heat flux density of heat exchanger can be everywhere near even, then the overall heat exchange effect of heat exchanger is best, approaches evenly for making q, can realize by adjusting overall heat transfer coefficient k and temperature difference t, for this reason, should adopt the reasonable pipe of heat exchange effect in the monophase field;
5) the heat exchange reinforcement and the pressure loss are complementary
In the incipient stage of two-phase section, can adopt dual flow path to arrange, coolant distribution to reduce flow velocity, is reduced pressure drop.Select best branch chalaza position by experiment;
6) follow a synergistic principle
The collaborative degree in field that has just entered the regional velocity of fin and thermograde at air is better, and the measure effect of augmentation of heat transfer is not obvious, but resistance is obviously increased; At the fin rear portion, since the fluid separation, the collaborative degree variation of thermograde and speed, and the measure effect of enhanced heat exchange is obvious.Therefore, should not crack or crack less in the fin front portion, or adopt that reinforcing degree is weak, the relatively low fin of pressure drop, and the fin surface of high heat-transfer performance such as the doube bridge fin that cracks then should be adopted in the rear portion of fin.
The heat exchanger of making according to said method is: the refrigerant flow direction is opposite with air-flow direction; During as condenser, the side-entrance of heat exchanger refrigerant is a gaseous state, and the refrigerant import is arranged on the heat exchanger lower end; Exit refrigerant liquefy, outlet is arranged on the lower end, and heat exchanger is then opposite when using as evaporimeter, and import and export all is arranged on the upper end, has seam in the middle of condenser and evaporimeter two array of pipes; Be provided with strengthening effect riffled tube preferably in the monophase field, be provided with the less thermoexcell of resistance at two-phase section; Adopt the doube bridge sheet that cracks at the air outlet slit place,, adopt crack less fin or flat sheet at the air intlet place.
Adopt stream of the present invention to arrange that the heat exchanger of making can significantly improve the heat exchange property of heat exchanger in refrigeration and the air-conditioning equipment, and along with the increase of mass velocity, the effect that improves can be more obvious, thereby reduce to freeze and the volume of air-conditioning equipment, reduced the cost of product.
Four, description of drawings
Fig. 1 is the structural representation that heat exchanger flow circuit of the present invention is arranged, Fig. 1 (a) is the structural representation of refrigerant of the present invention when being gaseous state, and Fig. 1 (b) is the structural representation of refrigerant of the present invention when being liquid state;
Fig. 2 be in the general condenser along journey thermal resistance distribution schematic diagram;
Fig. 3 be in the general condenser the coefficient of heat transfer along the journey distribution map;
Fig. 4 be in the general condenser along journey pressure drop distribution map, wherein dotted line is represented the pressure at pipe joint place.
Five, the specific embodiment
Referring to Fig. 1, stream method for arranging of the present invention is as follows:
1) pure counter-flow arrangement
According to the thermal conduction study basic principle, the mean temperature difference maximum of adverse current under identical out temperature condition, the mean temperature difference minimum of following current.So under identical cold fluid and hot fluid temperature, adopt counter-flow arrangement to be better than following current and arrange that promptly the refrigerant flow direction is opposite with air-flow direction;
2) prevent reverse heat conduction in the fin
The import of cold-producing medium and outlet all are in of heat exchanger together, have the bigger temperature difference in the fin at this place, inevitably reverse heat conduction can take place.For fear of reverse heat conduction, the way of employing is that two comb mid portions at heat exchanger crack.The employing part is cracked rather than whole cracking is because the temperature difference in the part fin that do not crack is very little, can ignore the influence of reverse heat conduction.In addition, part is cracked and is convenient to make and installation.
3) layout of heat exchanger inlet and outlet
Because gravity can make liquid automatically flow to lower from eminence, so should allow liquid enter the lower outflow in the stream as much as possible, to reduce flow resistance from eminence.When heat exchanger was done the condenser use, because condenser refrigerant side-entrance place phase is a gaseous state, the exit was liquid, so the import and the outlet of heat exchanger is arranged on the lower end optimum; When using as evaporimeter, because the import refrigerant of evaporimeter is liquid, thus opposite with condenser, import and export and all be arranged on the upper end.
4) make heat exchanger local heat flux density near even
According to waiting hot-fluid principle, if the local heat flux density of heat exchanger can be everywhere near even, then the overall heat exchange effect of heat exchanger is best.Need to make analysis-by-synthesis to managing the inside and outside thermal resistance and the temperature difference for this reason.According to q=k Δ t, q is approached evenly, can realize by adjusting overall heat transfer coefficient k and temperature difference t.
With the heat exchange in the general condenser is example, and the thermal resistance of refrigerant side and the coefficient of heat transfer distribute along journey and be shown in qualitatively among Fig. 2, Fig. 3.Obviously, the refrigerant thermal resistance of monophase field is much larger than the thermal resistance of two-phase section, and wherein the thermal resistance with air side is suitable in steam side monophase field, for making whole exchanger heat current density near evenly, can consider suitably to reduce the coefficient of heat transfer of two-phase section.The line arrangement that employing is divided into two reduces the mass velocity of cold-producing medium by this method, thereby reaches the purpose that suitably reduces the coefficient of heat transfer and reduced the two-phase section resistance.
Because the refrigerant thermal resistance of monophase field is much larger than the refrigerant thermal resistance of two-phase section, and the on-way resistance of monophase field is relatively low.Therefore, take the reasonable pipe of heat exchange effect,, strengthen the monophase field intraductal heat exchange and also can receive certain effect as the stage teeth riffled tube.And needn't too much consider the consequence that the resistance that causes increases.
5) take all factors into consideration the heat exchange reinforcement and the pressure loss
General condenser along the distribution of journey pressure drop as shown in Figure 4.Obviously, in the incipient stage of two-phase section, because flow velocity is very high, pressure drop is very big, and the local coefficient of heat transfer in this area is also very big simultaneously, and from reducing pressure drop and waiting the hot-fluid principle, this area can adopt dual flow path to arrange, coolant distribution to reduce flow velocity.The result who does like this reduces the too high local coefficient of heat transfer, reduces pressure drop simultaneously.The distributor that this moment is suitable and the selection of branch chalaza position are crucial, need to come by experiment to determine.Experimental technique is very simple, and the position that only needs to change the branch chalaza under identical test condition is tested.By the branch chalaza position of relatively selecting the best to experimental result.
6) follow a synergistic principle
Area (the air side flow direction first comb subarea) velocity that enters fin at air is more consistent with the direction ratio of localized temperature gradients, the collaborative degree that is two fields, this area is better, the measure of augmentation of heat transfer (cracking) DeGrain as fin, but resistance can obviously increase.But at the fin rear portion, since the fluid separation, the collaborative degree variation of temperature gradient field and velocity field, and the measure of enhanced heat exchange can be received obvious effects.From this viewpoint, can not crack or crack less in the air intlet place, or adopting that reinforcing degree is weak, the relatively low fin (as the less flat sheet of even not cracking of cracking) of pressure drop, the air outlet slit place then can adopt the fin surface of high heat-transfer performance such as the doube bridge fin that cracks.
Above-mentioned 6 basic principles proposed by the invention both had been adapted to condenser, also were applicable to evaporimeter.When the more heat exchanger of deployment tube row number, these several principles are suitable for too.When specifically arranging stream, repugnance may occur between the different principles, need take all factors into consideration, catch principal element.
Referring to Fig. 1, the heat exchanger refrigerant flow direction that method for designing according to the present invention is made is opposite with air-flow direction; When the import refrigerant is gaseous state, utilize the lift of gas to reduce on-way resistance, this moment, cold media gas was entered by heat exchanger lower end import 1; In the time of the refrigerant liquefy, utilize the gravity of liquid to reduce on-way resistance, the outlet 2 of heat exchanger also is placed on the lower end; When the import refrigerant was liquid state, refrigerant liquid was entered by heat exchanger upper end import 1; When refrigerant became gaseous state, the outlet 2 of heat exchanger also was arranged on the upper end; Adopted the measure that reduces reverse heat conduction, had seam 3 in the centre of two combs to reach the purpose that reduces reverse heat conduction; Make heat flow density as far as possible evenly by the form of selecting the inside and outside heat exchange surface of pipe; Because the refrigerant thermal resistance of monophase field 7 is much larger than the refrigerant thermal resistance of two-phase section 6, and the on-way resistance of monophase field 7 is relatively low.Therefore, the 7 stage teeth riffled tubes of taking good effect of heat exchange are strengthened monophase field intraductal heat exchange effect in the monophase field; And adopt the less single riffled tube of resistance at two-phase section 6.Air side fins is followed a synergistic principle, adopts the doube bridge sheet 4 that cracks at the air outlet slit place; At the air intlet place, adopt crack less fin even flat sheet 5.
The method for arranging of heat exchanger flow circuit also can be designed the heat exchanger of other concrete structure according to the present invention.