WO2007004176A1

WO2007004176A1 - A heat exchanger and a washing machine wherein this heat exchanger is utilized

Info

Publication number: WO2007004176A1
Application number: PCT/IB2006/052209
Authority: WO
Inventors: Alper Soysal; Tugrul Kodaz
Original assignee: Arcelik AS
Current assignee: Arcelik AS
Priority date: 2005-07-01
Filing date: 2006-06-30
Publication date: 2007-01-11
Anticipated expiration: 2008-01-01
Also published as: TR200708913T1

Abstract

The present invention relates to a heat exchanger (1) that provides the thermal energy of the hot water to be stored before being discharged out and the stored thermal energy to be absorbed by the cold water to be taken into the washing cycle.

Description

A HEAT EXCHANGER AND A WASHING MACHINE WHEREIN THIS HEAT EXCHANGER IS UTILIZED

[0001] The present invention relates to a heat exchanger comprising a phase changing material and a washing machine wherein this type of heat exchanger is utilized.

[0002] In washing machines, especially in dishwashers, the washing cycle is comprised of steps wherein hot and cold water is used. The cold water from the main supply is heated by means of a heater within the dishwasher to be used in the steps requiring the use of hot water. After these steps, the hot water mixed with the dirt from the dishes is discharged out of the dishwasher. The energy required for heating the water is among the leading factors that contribute to the increase of energy consumption of the dishwasher.

[0003] In the steps of the washing cycle requiring hot water, it is possible to store the thermal energy of the hot water for later use before being discharged out. Hence the heater can be operated for shorter time periods providing a reduction in the energy consumption of the dishwasher.

[0004] In state-of-the-art applications, the hot water to be discharged from the washing cycle is discharged by first being passed through a heat exchanger comprising a phase changing material (PCM) having a eutectic characteristic- having a lower melting point than the components forming it -. So most of the heat energy of the discharged water is stored in the heat exchanger by means of the phase changing material. The heat stored in the heat exchanger is transferred to the cold water taken from the main supply to be used in the washing cycle again by means of the phase changing material. Consequently, the heater used for heating the cold water from the main supply operates at a minimum level to heat the cold water.

[0005] In the state-of-the-art, in German Patent Application no. DE2501165, the hot water used in the washing cycle in a dishwasher is passed through a heat exchanger before being discharged out of the cycle to store its heat in the heat exchanger. Later on, the cold water taken into the heat exchanger absorbs this latent heat.

[0006] In the-state-of-the art, in German Patent Application no. DE4403737, a description is given of a dishwasher comprising a heat exchanger having a phase changing material that is in contact with both hot and cold fluid circuits wherein the fluids are in contact with only the phase changing material.

[0007] In the state-of-the-art European Patent no. EPl 111118, a heat exchanger is described which comprises a channel having phase changing material that separates a cold water conduit and a hot water conduit. The cold water flows through the cold water conduit in such a way that it flows from both sides of the channel having phase changing material in a direct flow and a counter flow direction and thus providing for a maximum heat transfer.

[0008] In the state-of-the-art United States Patent no. US5220954, a heat exchanger for a phase changing material is provided which comprises a container holding the phase changing material and a tube mounted on the container, coaxial with and surrounding the container. The heat exchanger comprises more than one passageways, situated on the duct, extending radially out from the duct. These passageways increase the heat transfer from the duct to the phase changing material. In this application, the heat of the fluid in the hot or cold cycles is preserved.

[0009] The aim of the present invention is to design a heat exchanger that can provide an efficient heat transfer between the cold and hot water flowing through it by means of the phase changing material.

[0010] Another aim of the present invention is to design a washing machine that economizes energy by using the thermal energy of the water to be discharged utilizing a heat exchanger.

[0011] The heat exchanger realized in order to attain the aim of the present invention explicated in the first claim and the dependent claims, comprises a hot water chamber inside which hot water is stored and/or conveyed and a cold water chamber that surrounds the hot water chamber. The heat exchanger provides for storing the thermal energy of the hot water and for transferring the stored thermal energy to the cold water received into the cold water chamber.

[0012] The heat exchanger comprises fins situated in the cold water chamber receiving the cold water for effectively storing and when required absorbing the thermal energy of the hot water flowing through the hot water chamber. These fins extend radially from the hot water chamber towards the wall of the cold water chamber. Phase changing material is placed inside the fins. Consequently a heat exchanger that provides a more effective heat transfer than conventional heat exchangers having phase changing material is accomplished.

[0013] In this embodiment of the present invention, the cold water is received between the fins. Thus a greater amount of cold water contacts the fins, the thermal energy stored in the phase changing material in each of the fins can be transferred from a wider surface area to a greater amount of cold water.

[0014] In another embodiment of the present invention, the fins rest against the wall of the cold water chamber, dividing the cold water chamber into separate sections that do not have water passage from one to the other. Consequently the cold water received into the cold water chamber is contacted to both sides of the fin resulting in the transfer of the thermal energy stored in the phase changing material contained in the fin to a greater amount of cold water.

[0015] The cells situated within the fin, inside which phase changing material is contained, are separate without a passage of the phase changing material between the cells. Thus during the phase change of the phase changing material, its sectional accumulation is prevented and thus fins having the same amount of phase changing material and respectively an equal rate of thermal energy transfer from the hot water chamber to the phase changing material situated inside the fins is provided.

[0016] Since the surface of the fin contacting the hot water chamber is produced as wide as possible, the phase changing material, being in the solid phase initially, melts relatively fast and an effective absorption of the thermal energy of the hot water flowing through the hot water chamber by the phase changing material is provided.

[0017] The cross - sectional area of the cell of the fin, inside which the phase changing material is contained, decreases from the hot water chamber towards the wall of the cold water chamber. As a result, more cold water is received into the chamber and the contact area of the cold water with the fin and respectively the phase changing material inside the fin is increased. Due to the decrease of the cross - sectional area of the cell containing the phase changing material, phase changing material inside the cell stays in the closest position to the hot water chamber during the phase change, the cold side of the phase changing material being in steady contact with the hot water chamber provides the effective transfer of the thermal energy of the water in the hot water chamber to the phase changing material.

[0018] As the phase changing material placed in the fins in the upper portion of the heat exchanger changes from solid to liquid phase, the solid part of it with a greater density is provided to stay closer to the hot water chamber as a result of gravity. And as the phase changing material placed in the fins in the lower portion of the heat exchanger changes from solid to liquid phase, the solid part of it with greater density is prevented from distancing away from the hot water chamber, making the phase changing material stay near the hot water chamber since the cross - sectional area of the cell containing the phase changing material gets narrower.

[0019] All the surfaces of the heat exchanger of the present invention contacting the outer surroundings are covered with an insulating material. As a result, heat transfer between the heat exchanger and the outer surroundings is prevented, enabling the protection of the stored thermal energy as needed.

[0020] The heat exchanger realized in order to attain above mentioned aim of the present invention is shown in the attached figures, where:

[0021] Figure 1 - is the perspective view of the heat exchanger.

[0022] Figure 2 - is the cross - sectional view of the heat exchanger.

[0023] Figure 3 - is the perspective view of the insulator, hot and cold water chambers and the fins.

[0024] Figure 4 - is the perspective view of the fins. [0025] Figure 5 - is the perspective view of the hot water chamber, cold water inlet and outlet and the fins. [0026] Figure 6 - is the schematic view of a washing machine comprising a heat exchanger. [0027] Elements shown in figures are numbered as follows:

1. Heat exchanger

2. Cold water chamber

3. Fin

4. Hot water chamber

5. Cold water inlet

6. Cold water outlet

7. Separator

8. Insulator [0028] 100. Washing machine [0029] 101. Washing tub [0030] 102. Cold water duct

[0031 ] 103. Hot water discharge duct

[0032] The heat exchanger (1) of the present invention comprises a hot water chamber (4) receiving the hot water in, a cold water chamber (2) filled with cold water surrounding the hot water chamber (4), and more than one fin (3) extending radially from the hot water chamber (4) to the wall of the cold water chamber (2), containing the phase changing material (P) inside (Figure 1).

[0033] Each of the fins (3) comprises one or more cells inside which phase changing material (P) is placed. The cells containing phase changing material (P) are provided separately in such a way such that passage of phase changing material (P) between them is inhibited. Thus, the regional accumulation of the phase changing material (P) is prevented.

[0034] The fins (3) are positioned around the hot water chamber (4) so as to surround it. The surface of the fin (3) contacting the hot water chamber (4) is made wider so that the amount of phase changing material (P) contacting the hot water chamber (4) is increased. Consequently the thermal energy of the hot water flowing through the hot water chamber (4) is transferred from the wall of the hot water chamber (4) to the phase changing material (P).

[0035] The fins (3), surrounding the hot water chamber (4), prevent the cold water received into the cold water chamber (2) from contacting the wall of the hot water chamber (4). Futhermore the cold water received into the cold water chamber (2) is provided to contact both sides of the fin (3). Consequently the thermal energy stored in the phase changing material (P) contained in the fin (3) is transferred to the cold water.

[0036] The heat exchanger (1) comprises an insulator (8) covering the cold water chamber (2) to provide the protection of the stored thermal energy for a time period and to decrease the heat transfer between the heat exchanger (1) and the outer surroundings (Figure 2 and Figure 3).

[0037] The cold water chamber (2) comprises one or more cold water inlets (5) for the intake of cold water from the main supply. Preferably, the cold water received from the cold water inlet (5) is collected in a collecting space (F) situated inside the cold water chamber (2) before entering in between the fins (3).

[0038] The cold water chamber (2) comprises one or more cold water outlets (6) for discharging the cold water, the temperature of which is changed, out of the heat exchanger (1). The cold water, after exiting out of the fins (3) and before being discharged out of the heat exchanger (1), is preferably collected in a distribution space (B) inside the cold water chamber (2) and the water collected here is discharged out of the heat exchanger (1) through the cold water outlet (6).

[0039] In the preferred embodiment of the present invention, the cross-sectional area of the cell containing the phase changing material (P) inside the fin (3) decreases from the hot water chamber (4) towards the wall of the cold water chamber (2). As a result, more cold water is received into the cold water chamber (2) between the fins (3) and the contact surface of the cold water with the fins (3) and respectively with the phase changing material (P) inside the fin (3) is increased. Furthermore, the solid part of the phase changing material (P) situated inside the fin (3) is provided to steadily get near the hot water chamber (4) during the phase change, and contact the hot water chamber (4) as a result of the fin (3) comprising a cell containing the phase changing material (P) with a cross-sectional area decreasing from the hot water chamber (4) towards the cold water chamber (2) (Figure 4 and Figure 5).

[0040] In another embodiment of the present invention, the fins (3) extending from the hot water chamber (4) to the wall of the cold water chamber (2) contact the wall of the cold water chamber (2). Thus the fins (3) divide the cold water chamber (2) into separate independent sections that do not have water passage from one to the other. As a result, the cold water flows in between the fins (3) providing the thermal energy stored in the phase changing material (P) in each fin (3) to be transferred to the cold water (Figure 2).

[0041] In another embodiment of the present invention, the fins (3) extending from the hot water chamber (4) to the wall of the cold water chamber (2) do not contact the wall of the cold water chamber (2).

[0042] In yet another embodiment of the present invention, cold water is received into the cold water chamber (2) through two cold water inlets (5). In this embodiment, cold water chamber (2) comprises a separator (7) that divides the collecting space (F) into two parts such that each has one cold water inlet (5). So the water received from the cold water inlet (5) can reach between the fins (3) more effectively (Figure 6).

[0043] The heat exchanger (1) of the present invention is utilized in a washing machine (100). The washing machine (100) comprises a washing tub (101) inside which items to be washed are placed, a hot water discharge duct (103) for discharging the water used in the washing tub (101) and a cold water duct (102) for intake of the cold water from the main supply into the washing tub (101) (Figure 7). The heat exchanger (1) is connected to the cold water duct (102) and the hot water discharge duct (103). The cold water inlet (5) is connected to the cold water duct (102) and the cold water outlet (6) is connected to the washing tub (101). After the water discharged from the tub (101) is received in the hot water chamber (4) by means of the hot water discharge duct (103), it is discharged from the heat exchanger (1), again by means of the hot water discharge duct (103).

[0044] The cold water received from the main supply is taken into the cold water chamber (2) by means of the cold water inlet (5) that is connected to the cold water duct (102) before being taken into the washing tub (101) and after its temperature is changed, is discharged out of the heat exchanger (1) from the cold water outlet (6) by means of the cold water duct (102). The thermal energy of the hot water is stored before it is discharged and the stored thermal energy is absorbed by the cold water to be received into the washing cycle before it is transferred to the washing tub (101).

[0045] The washing cycle of the above described washing machine (100) comprising a heat exchanger (1) is explicated below:

[0046] Following the completion of the steps wherein hot water is used, the hot water is taken into the hot water chamber (4) before being discharged out of the washing machine (100). The thermal energy of the hot water taken into the hot water chamber (4) is transferred to the fins (3) situated on the hot water chamber (4) and containing the phase changing material (P) inside. The thermal energy transferred to the fins (3) is conducted to the phase changing material (P) which is initially solid. As the temperature exceeds the critical value of phase change, the phase changing material (P) starts to change phase, i.e. to melt, from its part near the hot water chamber (4). The melting process proceeds in boundary layers as a result of the fact that the colder phase changing material (P) is in continuous contact with the hot water chamber (4) the phase changing material (P) melts effectively. The thermal energy of the hot water is stored by means of the phase changing material (P) changing phase from solid to liquid.

[0047] In the washing machine (1), when the steps of the washing cycle using hot water are started, cold water is taken in from the main supply. The cold water taken in from the main supply is received into the heat exchanger (1) through the cold water inlet (5) before being conveyed into the washing tub (101). The cold water entering the heat exchanger (1) through the cold water inlet (5) fills up the cold water chamber (2) by being taken in between the fins (3). The thermal energy stored in the phase changing material (P) contained within the fins (3) is absorbed by the cold water that is colder than the temperature of the phase changing material (P) by means of contacting the fins (3) and flowing towards the cold water outlet (6). During this transfer of heat, the phase changing material (P) again starts changing phase from liquid to solid.

[0048] As a result of all these processes, the thermal energy of the hot water used in the previous washing cycle and discharged from the washing machine (100) is utilized in the heating of the cold water taken into the washing cycle.

[0049] The washing machine (100) comprising a heat exchanger (1) of the present invention is preferably a dishwasher or a laundry washing machine.

[0050] By utilizing the heat exchanger (1) of the present invention, an efficient heat transfer is enabled between the hot and cold water flowing through it.

[0051] The energy consumption of the washing machine (100) is substantially reduced by utilizing the thermal energy of the hot water discharged out of the washing machine (100).

Claims

[0001] A heat exchanger (1) comprising a hot water chamber (4) into which the hot water is taken, a cold water chamber (2) into which the cold water is taken, surrounding the hot water chamber (4) and characterized by more than one fin (3) containing phase changing material (P), extending radially from the hot water chamber (4) to the wall of the cold water chamber

(2).

[0002] A heat exchanger (1) as in Claim 1, characterized by fins (3) comprising one or more cells containing phase changing material (P) which are separate such that the passage of the phase changing material (P) between them is prevented.

[0003] A heat exchanger (1) as in Claim 1 or 2, characterized by fins (3), the surfaces of which contacting the hot water chamber (4) are made wider so that the amount of the phase changing material (P) contacting the hot water chamber (4) is increased and the thermal energy of the hot water in the hot water chamber (4) is transferred from the wall of the hot water chamber (4) to the phase changing material (P).

[0004] A heat exchanger (1) as in any one of the Claims 1 to 3, characterized by fins (3) positioned around the hot water chamber (4) such that they surround the hot water chamber (4).

[0005] A heat exchanger (1) as in any one of the Claims 1 to 4, characterized by a fin

(3), with the cross - sectional area of the cell containing the phase changing material (P), decreasing from the hot water chamber (4) towards the wall of the cold water chamber (2).

[0006] A heat exchanger (1) as in any one of the Claims 1 to 5, characterized by a fin (3) that separates the cold water chamber (2) by contacting the wall of the cold water chamber (2) such that there is no passage of cold water between them.

[0007] A heat exchanger (1) as in any one of the Claims 1 to 5, characterized by a fin (3) that does not contact the wall of the cold water chamber (2).

[0008] A heat exchanger (1) as in any one of the Claims 1 to 7, characterized by an insulator (8) covering the cold water chamber (2) for providing the protection of the stored thermal energy for a desired time period and reducing the heat transfer between the heat exchanger (1) and the outer surroundings.

[0009] A heat exchanger (1) as in any one of the above claims, characterized by a cold water chamber (2) comprising one or more cold water inlets (5) for the intake of cold water from the main supply and one or more cold water outlets (6) for discharging out the cold water, the temperature of which is changed.

[0010] A heat exchanger (1) as in Claim 9, characterized by a cold water chamber (2) comprising a collecting space (F) inside which cold water is collected before entering in between the fins (3) and a separator (7) that divides the collecting space (F) into two parts such that there is one cold water inlet (5) in each one. A washing machine (100) comprising a heat exchanger (1) as in any one of the above claims, a washing tub (101) inside which items to be washed are placed, a hot water discharge duct (103) for discharging the water used in the washing tub (101) and a cold water duct (102) for conveying the cold water from the main supply into the washing tub (101), with a cold water inlet (5) connected to the cold water duct (102), a cold water outlet (6) connected to the washing tub (101) and a hot water discharge duct (103) connected to the hot water chamber (4).