FI69206B - VAERMEPUMPSYSTEM - Google Patents

Description

] ANNOUNCEMENT A Q Ο Π A

B 11 UTLÄGG NINGSSKRIFT O 7 Z U O

C / ilCY Fatent born 10 12 1935

Patent applications (51) Kv.lk.4 / lnt.CI.4 F 25 B 29/00 FINLAND —FINLAND (21) Patent application - Patentansökning 772510 (22) Application date - Ansökningsdag 23.08.77 (Fi) (23) Starting date - Giltighettdag 23.08.77 (41) Has become public - Blivit offentlig 08.03.78

National Board of Patents and Registration _ Date of publication and publication - 30.08.85

Patent and Registration Publications '' Ansökan utlagd och utl.skriften publicerad (32) (33) (31) Claim Requested — Begird prloritet 07.09.76 07.09.76 USA (US) 720721, 720722 (71) Carrier Corporation, Carrier Tower, P.O. Box 4800, Syracuse, New York 13221, USA (72) James J. Del Toro, Liverpool, N.Y., Rudy C. Bussjager, Syracuse,

The present invention relates to a reversible cooling system adapted to operate at optimum efficiency in either the heating or cooling mode of the operation. Companies The New York, USA (US) (74) The Kolster Ab (54) Heat Pump System - Värmepumpsystem

In particular, the heat pump which is the subject of the present invention has control devices which automatically control the refrigerant in each heat exchanger depending on the operation of the exchanger, whereby each exchanger operates efficiently as either a condenser or an evaporator.

Most air-side heat exchangers used in cooling systems are constructed of a fin plate, and the coolant as it passes through the unit is directed through a plurality of heat transfer zones through flow circuits. When the exchanger is used as a cooler, the flow of coolant is passed through the circuits so that it passes successively through each zone. On the other hand, when the exchanger is used as an evaporator, the coolant is usually passed through each circuit simultaneously, thereby creating a parallel flow through the circuits. It can be seen that the flow geometry of a well-designed 69206 condenser is not compatible with a well-designed evaporator.

When designing a heat pump, the design of the heat exchanger is usually adapted to provide the required dual function of the exchanger. This in turn limited the performance of the entire system.

U.S. Patent No. 3,024,619 discloses a heat pump system in which the second heat exchanger has a separate subcooling coil and only this heat exchanger has two heat transfer zones.

U.S. Patent No. 2,716,870 discloses a heat pump system in which subcooling is provided by a heat pump exchanger. The exchanger has four circuits, three of which are connected in series with one circuit. It does not mention the change in the flow path through the heat exchanger depending on the mode of operation.

U.S. Patent No. 3,977,210 discloses a heat exchange system with various circuits. In this system, valves are used to change the circuit between the heat exchangers under certain conditions. These valves in no way affect the circulation of coolant through the heat exchanger and the circuit of the internal heat exchanger remains unchanged regardless of whether the heat exchanger acts as an evaporator or a condenser.

The object of the invention is to improve known heat pump systems, with the aim of developing a heat pump system which automatically controls the flow of coolant in the system so that the system operates efficiently in both cooling and heating mode.

These and other objects of the present invention are realized by means of a heat pump system, the features of which appear from the claimed claims.

The invention will now be described, by way of example, with reference to the accompanying drawing, in which Figure 1 is a diagram of a reversible cooling system utilizing the present invention; Figure 2 is a partial perspective view showing a multi-circuit heat exchanger utilizing the teachings of the present invention; Fig. 2 is a partial front view of the heat exchanger shown in Fig. 3, Fig. 5 schematically shows the flow circuits of the exchanger of Figs. 2-4, and Fig. 6 is an enlarged sectional view of a capillary feeding one flow circuit of the exchanger shown in Figs. .

Figure 1 shows the simplest form of the invention utilized in a reversible steam compression system, generally reference numeral 10. The system consists of a compressor 11 of any suitable design and two refrigerant heat exchangers 12 and 13, typically ribbed coils specially made. to exchange energy between the air flowing over the plates and the refrigerant flowing in the flow circuit of the exchanger. For the purposes of this disclosure, the heat exchanger 12 is referred to as an internal coil and the heat exchanger 13 as an external coil. Functionally, both coils are connected to the compressor by a four-way valve 15 which selectively directs the exhaust steam of the compressor to either exchanger. When the system acts as a cooler, the discharge proceeds through a pipe 16 to a primary tank 17 which is separate from the external coil. In this case, the suction side of the compressor is operatively connected to the primary tank 33 by a pipe 36. When the four-way valve is turned, the flow direction of the coolant in the system is reversed and the functions of the heat exchangers change accordingly.

Initially, the operation of the system will be described as the system acting as a radiator, whereby the external coil 13 is made to act as a radiator. The cooling steam accumulated in the primary tank, i.e. in the upper tank 17, flows downwards through the cooling circuit. The coolant passes through two heat exchange zones: the upper zone A and the lower zone B. The two zones are separated by a return tank 14, which acts as a tank between the zones of refrigerant moving from one zone to another.

After passing through both heat exchange zones, the coolant enters the lower secondary tank 18, which is part of the inner coil. The lower container 18 is in flow communication with the secondary container 31 belonging to the inner coil by means of a liquid pipe 23. It should also be noted that the lower tank 18 is also in flow communication with the upper tank 17 by means of a pipe 20 which bypasses the circuit of the heat exchanger. The non-return valve 21 is located in the bypass pipe. When the external coil acts as a condenser, the valve stays closed due to the pressure difference created in the exchanger as the refrigerant changes from steam to liquid. As a result, the coolant collected in the lower or secondary tank is prevented from flowing back to the primary tank through the pipe 20 when the exchanger acts as a cooler.

The liquid coolant accumulated in the tank 18 passes along the liquid pipe 23 through the second non-return valve 24. The non-return valve 24 is arranged to open when the system acts as a radiator, whereby the coolant is directed to the second inner coil 12. A second non-return valve 25 is also placed in the liquid pipe near the secondary tank 31 associated with the inner coil. The non-return valve 25 is adapted to act opposite the non-return valve 24, whereby the coolant is prevented from flowing directly from the liquid pipe to the tank 31. The coolant must therefore be transported to the manifold 27 located in front of the non-return valve 25 in the flow direction.

The flow from the manifold is divided into two separate streams by means of a pair of hairpieces 28, 29. As shown in Figure 1, the hair follicles lead to a centrally located return container 30 which acts as a collector between the zones of the inner coil. In practice, the hairpins go into the return tank and end deep into the circuit tubes attached to the tank. It follows that part of the coolant spreads to the upper heat transfer zone C and part to the lower heat transfer zone D. Under the action of the liquid pressure, part of the coolant flows up , through which the refrigerant moves simultaneously. One path passes the coolant through the heat transfer zone C and the other through the heat transfer zone D.

Just like the external exchanger, the internal exchanger has a bypass tube 34 which brings the primary tank 33 into flow communication with the secondary tank 31. A non-return valve 35 is located in the bypass pipe and is adapted to open during the operation of the exchanger 12 as a radiator. When the non-return valve 35 is open, both tanks 31 and 33 open on the suction side of the compressor along the pipe 36, whereby the circulation is closed.

When the operating mode of the system is changed, which is done by turning the four-way valve, the flow of coolant in the system is reversed. This in turn switches the operation of both exchangers. In this case, the position of the four non-return valves changes. The bypass tube 20 opens and the tube 34 closes. Correspondingly, the non-return valve 25 opens and the non-return valve 24 closes.

The material leaving the compressor passes through a pipe 36 through a tank 33 to an inner coil, which now acts as a condenser, and from there to a lower tank 31. As it passes through the inner coil, the refrigerant passes through each of the heat transfer zones C and D. From the tank 31, the coolant flows along the liquid pipe towards the outer helix. However, the flow is blocked by a non-return valve 24 which directs the coolant to the distribution pipe 37, where the flow is divided into two parts by means of hairpins 38 and 39.

The hair whistles pass through the inter-zone tank, i.e. the return tank 14, to the circuits belonging to the heat transfer zones A and B. Here, the flow is again split in two, with one part of the flow directed to the secondary tank 18 and the other to the primary tank 17. Both tanks are connected to the compressor suction side by means of an open bypass pipe 20 and pipe 16 and the heating circuit is terminated.

As can be seen from the above description, the flow of coolant through the heat exchangers is automatically controlled so that the flow geometry through each exchanger changes depending on whether the exchanger is used as a condenser or an evaporator. That is, when the heat exchanger is adapted to act as a radiator, the coolant successively flows through the heat exchange zones of the exchanger. Correspondingly, the coolant flows simultaneously, i.e. in parallel, through the heating zones when the exchanger acts as an evaporator. Thus, the efficiency of the system can be optimized in both heating and cooling mode, which was previously an unattainable result because the system became constrained as a result of the trade-offs required by the design of the heat exchanger.

It will be apparent from the foregoing description that the system is not necessarily limited to containers used with exchangers when the invention is used with a simple exchanger. On this basis, the 69206 tank can be replaced with standard piping that can simplify the flow of refrigerant into and out of the exchanger.

Accordingly, the present invention can be applied to a group of coils which travels through a plurality of coils to the rear and forward through a gear unit. A group of coils, such as those typically used in large cooling systems, are shown in Figures 2-4. For the sake of clarity, the coil must be considered as an external coil used in the cooling system corresponding to Figure 1.

Figures 2 to 4 show a spiral of a circuit group consisting of several coolant flow circuits. The coil has two overlapping rows of finned tubes: an inner row 40 and an outer row 41 extending at the rear and front outside the heat exchanger. The rows are connected to each other by means of return arcs 42, whereby a number of individual coolant flow circuits having the above-mentioned geometry are formed. Typically, each end of each circuit is introduced from the helical apparatus through the tubes of one apparatus, for example through a support plate 45, so that the inlet and outlet openings of each circuit are suitably located on the same side of the exchanger.

In the group of coils described herein, the coil consists of seven flow circuits arranged to pass through three heat transfer zones. However, it will be apparent from the following discussion that the number of circuits and heat transfer zones may vary depending on the design conditions.

Along the side of the coil, a tank network is arranged adjacent to the pipe mounting plate 45 and adapted to operate with two non-return valves to direct the flow of coolant through the heat exchanger as described above when the exchanger acts as a system cooler and differently as an evaporator. The tank has a primary tank 47, a dysfunctional or inter-zone tank 48, a secondary tank 49 and a liquid tank 46. It should be noted that the primary and secondary tanks are axially parallel to the inner chambers of each tank and are separated by a check valve 51. 50 operatively connected to the compressor by a four-way valve (not shown).

When the coil acts as a condenser, hot high-pressure steam is introduced into the primary tank via a pipe 50 and closes the non-return valve 51. The closing of the valve separates the chamber 47 of the tank 47 from the chamber 49 of the tank. The now insulated primary tank supplies coolant to the four flow circuits through supply lines 52. The four circuits fed by the tank 47 are located at the bottom of the coil and form the first heat transfer zone, denoted here by zone E.

A simplified schematic description of the flow through the heat exchanger is shown in Figure 5. We believe that the use of the diagram in conjunction with the drawings of Figures 2-4 will help to better understand the geometry of the flow through the exchanger.

After passing through the heat transfer zone E formed by the four flow circuits, the coolant enters the inactive tank 48 between the zones through the outlet pipe 53. The pressure difference pushes the coolant upwards through the inoperative tank, and the coolant discharges into the two upper circuits of the coil through the supply pipes 54. The two upper coolant flow circuits consist of a second, smaller heat transfer zone F.

After passing through the helical box, the coolant of the two upper circuits is directed to the secondary tank 49 through the discharge pipe 56. The coolant collects in the tank 49 and passes to the last flow circuit through one supply pipe 58. The last circuit passes through the third and last heat transfer zone, zone G, and terminates in the liquid tank 46.

The last heat transfer zone is preferably located in the middle of the coil, whereby the heat transfer properties of the coil increase. For clarity, the last heat transfer zone in the figure is located at the top of the heat exchange equipment.

The coolant, which is now in a liquid state, collects in the liquid tank 46 and passes through the open non-return valve 61 to the T-connector 62. From the connector, the coolant flows down the liquid pipe 60 towards the inner coil (not shown).

As can be seen from the above description, the tank network, together with the non-return valves, guides the refrigerant from the compressor successively through the heat transfer zones. In addition, the number of flow circuits decreases in each zone as it progresses in the direction of flow. By dividing the coil in zones in this way, the flow geometry of the coil is adjusted according to the increase in the density of the liquid, whereby the optimum power of the coil is achieved when the coil acts as a cooler.

When the operating mode of the system is changed, the operation of the coil changes accordingly. In the heating mode, the liquid coolant passes through the liquid pipe 60 towards the non-return valve 61. However, the valve has automatically closed because the pressure across the valve has changed. The coolant thus advances to the distribution tube 63 attached to the T-connector 62. The flow from the distribution tube is divided into seven parts by the hair whistles 65. It should be noted that the number of hair whistles is equal to the number of flow circuits passing through the coil.

It is best seen from Figure 6 that the six capillaries pass through the inoperative container and extend into the supply tubes 54 belonging to the four circuits of the heat transfer zone E and the discharge tubes 53 belonging to the two circuits of the heat transfer zone F. The capillaries extend deep into the tubes of the different flow circuits so that the coolant coming through the capillaries swells well in each circuit. This in turn prevents coolant transfer between circuits in an inoperative tank. Since the inoperative tank has a substantially constant pressure, the coolant is evenly distributed in each circuit.

The seventh hairpiece terminates in a fluid reservoir 46 having substantially the same pressure as the inoperative reservoir. The tank 46 in turn leads to a circuit belonging to the heat transfer zone G.

It should be noted that this time the non-return valve 51 between the primary and secondary tanks 47 and 49 has now turned open, so that the tanks communicate with each other and form a single flow path through the pipe 50 to the compressor. It is best seen in Figure 5 that the seven flow circuits are discharged into the tanks 47 and 49 when the coil acts as an evaporator. The circuits belonging to zones G and F terminate in the tank 49 via pipes 56 and 48 and the four circuits belonging to zone E terminate in the tank 47 via pipes 52.

Thus, if the heat exchanger is to act as an evaporator in the system, the flow geometry in the coil changes automatically, and the coolant flows simultaneously as a parallel flow through all the circuits, and thus through all the heat transfer zones.

This parallel flow through the coil generates optimum power for the 11 9 69206 exchanger when the exchanger is used as an evaporator.

Although the present invention has been described with reference to the accompanying construction, it is not limited to specific details as will be apparent from the following. For example, any device that disrupts the flow can be used in place of the hairpins, and modifications such as those set forth in the claims can be used for the throttling process.

Claims (3)

10 69206 A heat pump system with a compressor (11), a heat exchanger pair (12, 13) with flow circuits and a reversing valve (15) for selectively reversing the flow of coolant through the system so that the operation of the exchangers is also reversed, characterized in that it has devices to divide each exchanger into several heat transfer zones (A, B, C, D) and that each zone consists of several flow circuits (52, 56, 58) and has flow control devices that control the refrigerant discharged from the compressor to pass through each zone of one exchanger (17, 18, 20 or 31, 33, 35) and devices (63, 65) for directing coolant from said exchanger to a second exchanger, the flow passing simultaneously through each zone of said second exchanger, the flow through the zones being parallel, and that it has switching devices (23, 24, 25) operatively connected to one main with flow control devices and which automatically reverse the flow geometry through the exchangers, wherein the flow of coolant is parallel through said first exchanger and sequentially through said second exchanger. A heat pump system according to claim 1, characterized in that the first zone of the heat exchanger receiving coolant from the compressor (11) arranged as a condenser has a selected number of circuits and the next zone in the coolant flow direction has the same number or fewer circuits. Heat pump system according to claim 2, characterized in that there is one circuit in the last zone of the system.