HEAT PUMP AND HEAT PUMP UNIT USING SAME

Heat pump 10 has heat-absorbing section 12 that receives heat from an outside and heat-releasing section 13 that releases heat to the outside, for transferring heat between heat-absorbing section 12 and heat-releasing sectioning 13 by reinforcing and reducing a magnetic field applied to a primary working fluid circulating between heat-absorbing section 12 and heat-releasing section 13, wherein the primary working fluid is magnetic particle dispersion 11 containing magnetic particles 11 dispersed in a dispersion medium.

TECHNICAL FIELD

The present invention relates to a heat pump and a heat pump unit using the same, and particularly to a heat pump that uses a magnetic field to transfer heat and a heat pump unit using the same.

BACKGROUND ART

Conventionally, heat pumps have been used as a means of transferring heat from a low-temperature section to a high-temperature section. The heat pump receives heat from the low-temperature section and then raises the temperature of this heat to supply it to the high-temperature section, so that it can obtain high-temperature heat energy from low-temperature heat energy.

As such heat pumps, mechanical heat pumps with compressors have been commercialized. However, in heat pumps with compressors, noise caused by the compressor and complicated maintenance are recognized as problems and risks.

For example, Patent Literature 1 discloses a heat pump that uses a magnetic field to transfer heat. The heat pump disclosed in Patent Literature 1 includes particulate magnetic solids filled inside the device, and causes a magnetic field to be applied to or removing from the magnetic solids to exchange heat between the magnetic solids and a liquid working fluid flowing through a packed bed filled with the magnetic solids. This means that compared to heat pumps with compressors, noise caused by the compressor is not generated, and maintenance is easier.

CITATION LIST

Patent Literature

Patent Literature 1: JP 2019-509461 A

SUMMARY OF THE INVENTION

Technical Problem

In the heat exchange between the magnetic substances and the working fluid as described above, if the overall heat transfer coefficient depending on the condition of the heat transfer surface is U, the heat transfer area is A, and the temperature difference between the heat transfer surfaces is Δt, then the heat quantity Q to be exchanged is expressed as follows:

Therefore, to obtain a large heat quantity Q, the heat transfer area A and/or the temperature difference Δt between the heat transfer surfaces must be increased. To increase the heat transfer area A, it is necessary to increase the volume specific surface area by reducing the size of the magnetic particles. However, as disclosed in Patent Literature 1, in the heat pump that exchanges heat between the magnetic particles filled inside the device and the liquid working fluid, if the size of the magnetic particles is reduced, the pressure drop when the liquid working fluid flows through the packed bed increases. In this case, the work required to move the working fluid is increased, and the heat pump efficiency is reduced. Therefore, to obtain good efficiency, magnetic particles of relatively large size must be used. As a result, the area of contact between the magnetic substances in solid form and the liquid working fluid (i.e. the heat transfer area A) is limited.

On the other hand, to obtain a large heat quantity Q, the temperature difference Δt between the heat transfer surfaces may be increased. However, the heat pump has a problem that if the temperature difference Δt between the heat transfer surfaces is large, it is necessary to raise and lower the temperature of the working fluid extra for the temperature difference, resulting in a decrease in thermal efficiency.

The present invention has been made in view of the above problems of the prior art, and its object is to provide a heat pump that uses a magnetic field so that heat can be transferred with high efficiency, and a heat pump unit using the same.

Solution to Problem

To achieve the above objective, the present invention isa heat pump having a heat-absorbing section that receives heat from an outside and a heat-releasing section that releases heat to the outside, for transferring heat between the heat-absorbing section and the heat-releasing section by reinforcing and reducing a magnetic field applied to a primary working fluid circulating between the heat-absorbing section and the heat-releasing section,wherein the primary working fluid is a fluid containing magnetic particles dispersed in a dispersion medium.

The fluid may be a colloidal fluid or a suspension. In the following description, both cases where it is a colloidal fluid and where it is a suspension are collectively referred to as a magnetic particle dispersion.

In the present invention configured as described above, when reinforcing and reducing a magnetic field applied to the primary working fluid circulating between the heat-absorbing section that receives heat from the outside and the heat-releasing section that releases heat to the outside, the magnetic moments and entropy of the magnetic particles constituting the primary working fluid are changed to cause heat absorption, heat release, temperature rise, and temperature drop. In this case, since the primary working fluid is a magnetic particle dispersion which is a colloidal fluid containing magnetic particles dispersed in a dispersion medium, the size of magnetic particles in the primary working fluid is very small. Therefore, the heat transfer area between the magnetic particles and the dispersion medium is extremely large, which improves the efficiency of heat exchange between the magnetic particles and the dispersion medium of the primary working fluid, resulting in highly efficient heat transfer.

Further, if it includes a temperature-rising section in which the magnetic field applied to the primary working fluid that has passed through the heat-absorbing section is reinforced in an adiabatic environment and a temperature-dropping section in which the magnetic field applied to the primary working fluid that has passed through the heat-releasing section is reduced in an adiabatic environment, wherein the heat-absorbing section holds the primary working fluid that has passed through the temperature-rising section, with the magnetic field reduced, and wherein the heat-releasing section holds the primary working fluid that has passed through the temperature-rising section, with the magnetic field reinforced, heat can be transferred using the cycle based on the magnetocaloric effect.

Further, if a source of the magnetic field is a permanent magnet, the magnetic field is generated without the need for a power source.

In a heat pump unit using the above heat pump, if the heat pump is arranged in multiple stages such that the heat-absorbing section of the heat pump in a succeeding stage receives heat released in the heat-releasing section of the heat pump in a preceding stage, and the heat pump unit includes a heat-transfer assisting section that is arranged between the multiple stages of heat pumps and that receives heat released in the heat-releasing section of the heat pump in the preceding stage with a secondary working fluid and then gives the heat of the secondary working fluid to the heat-absorbing section of the heat pump in the succeeding stage, thermal energy can be transferred with a large temperature difference.

Further, in each of the multiple stages of heat pumps, if a magnetic material constituting the primary working fluid is individually selected depending on temperatures of heat to be absorbed in the heat-absorbing section and heat to be released in the heat-releasing section of each heat pump, the overall thermal efficiency is improved.

Further, if the secondary working fluid flows through a common channel with the primary working fluid that receives and gives heat, and if one of the primary working fluid and the secondary working fluid that flow through the common channel is hydrophilic and another is hydrophobic, the heat transfer resistance between the primary working fluid and the secondary working fluid is reduced to allow more efficient heat exchange, yet the primary working fluid and the secondary working fluid can be easily separated from each other after the heat exchange between them.

Advantageous Effects of Invention

According to the present invention, since the primary working fluid circulating between the heat-absorbing section that receives heat from the outside and the heat-releasing section that releases heat to the outside is a magnetic particle dispersion containing magnetic particles dispersed in a dispersion medium, the efficiency of heat exchange between the magnetic particles and the dispersion medium of the primary working fluid is improved, enabling highly efficient heat transfer using the magnetic field.

Further, in the heat pump including the temperature-rising section in which the magnetic field applied to the primary working fluid that has passed through the heat-absorbing section is reinforced in an adiabatic environment and the temperature-dropping section in which the magnetic field applied to the primary working fluid that has passed through the heat-releasing section is reduced in an adiabatic environment, wherein the heat-absorbing section holds the primary working fluid that has passed through the temperature-rising section, with the magnetic field reduced, and wherein the heat-releasing section holds the primary working fluid that has passed through the temperature-rising section, with the magnetic field reinforced, heat can be transferred using the cycle based on the magnetocaloric effect.

Further, in the heat pump wherein the source of the magnetic field is a permanent magnet, the magnetic field can be generated without the need for a power source.

Further, in the heat pump using with the heat pump, wherein the heat pump is arranged in multiple stages such that the heat-absorbing section of the heat pump in the succeeding stage receives heat released in the heat-releasing section of the heat pump in the preceding stage, and wherein the heat pump unit includes the heat-transfer assisting section that is arranged between the multiple stages of heat pumps and that receives heat released in the heat-releasing section of the heat pump in the preceding stage with a secondary working fluid and then gives the heat of the secondary working fluid to the heat-absorbing section of the heat pump in the succeeding stage, thermal energy can be transferred with a large temperature difference.

Further, in the heat pump unit wherein in each heat pump of the plurality of heat pumps, the magnetic material constituting the primary working fluid is individually selected depending on the temperatures of heat to be absorbed in the heat-absorbing section and heat to be released in the heat-releasing section of each heat pump, the overall thermal efficiency can be improved.

In the heat pump unit wherein the secondary working fluid flows through the common channel with the primary working fluid that receives and gives heat, and if one of the primary working fluid and the secondary working fluid that flow through the common channel is hydrophilic and the another is hydrophobic, the heat transfer resistance between the primary working fluid and the secondary working fluid is reduced to allow more efficient heat exchange, yet the primary working fluid and the secondary working fluid can be easily separated from each other after the heat exchange between them.

DESCRIPTION OF EMBODIMENTS

FIG.1shows a heat pump according to an embodiment of the present invention.

As shown inFIG.1, the heat pump according to this embodiment receives heat from heat-giving fluid20and releases heat to heat-receiving fluid30by means of magnetic particle dispersion11circulating through a channel. The channel for magnetic particle dispersion11is provided with heat-absorbing section12, temperature-rising section14, heat-releasing section13, temperature-dropping section and pump16.

Heat-absorbing section12is located close to a channel through which heat-giving fluid20flows. Heat-absorbing section12causes magnetic particle dispersion11to receive heat from heat-giving fluid20.

Temperature-rising section14is located downstream of heat-absorbing section12in the flow direction of magnetic particle dispersion11. Temperature-rising section14causes the temperature of magnetic particle dispersion11that has received heat in heat-absorbing section12to rise.

Heat-releasing section13is located close to a channel through which heat-receiving fluid30flows and downstream of temperature-rising section14in the flow direction of magnetic particle dispersion11. Heat-releasing section13causes magnetic particle dispersion11to release heat to heat-receiving fluid30.

Temperature-dropping section15is located downstream of heat-releasing section13in the flow direction of magnetic particle dispersion11. Temperature-dropping section15causes the temperature of magnetic particle dispersion11that has released heat in heat-releasing section13to drop.

Pump16is located between temperature-dropping section15and heat-absorbing section12in the channel for magnetic particle dispersion11. Pump16circulates magnetic particle dispersion11through the channel. The location of pump16is not limited to a location between temperature-dropping section15and heat-absorbing section12, as long as it can circulate magnetic particle dispersion11through the channel.

FIG.2shows the configuration of magnetic particle dispersion11shown inFIG.1.

Magnetic particle dispersion11shown inFIG.1is a primary working fluid in the present invention. As shown inFIG.2, magnetic particle dispersion11is a fluid containing magnetic particles11b, which are fine particles of magnetic material, dispersed in dispersion medium11a.

The characteristics of magnetic particles11bwill be described here.

When magnetic substances, such as magnetic particles11b, are placed in an environment where a magnetic field exists, the magnetic moments of the magnetic substances are aligned along the direction of the magnetic field. Then, if the magnetic field in the environment is reduced, the magnetic moments of the magnetic substances will point in different directions accordingly. Thus, the magnetic substances become “disordered”, which leads to an increase in their magnetic entropy.

When this process takes place in an adiabatic environment, the temperature of the magnetic substances drops according to the change in magnetic moments.

On the other hand, if a magnetic field is reinforced while magnetic substances are placed in an environment with a reduced magnetic field, the magnetic moments of the magnetic substances will point in the direction of the magnetic field accordingly. Thus, the magnetic substances become “ordered”, which leads to a decrease in their magnetic entropy.

When this process takes place in an adiabatic environment, the temperature of the magnetic substances rises according to the change in magnetic moments.

Heat pump10shown inFIG.1takes advantage of the cycle based on the magnetocaloric effect of magnetic particles11bas described above to receive heat from heat-giving fluid20and release heat to heat-receiving fluid30.

The specific operation of heat pump10shown inFIG.1will be described below.

FIG.3illustrates the specific operation of heat pump10shown inFIG.1.FIG.3shows the cycle characteristics of magnetic particles11bbased on the magnetocaloric effect. Note that H indicates the strength of the magnetic field, and H1<H2.

In heat-absorbing section12, heat is transferred from heat-giving fluid20to magnetic particle dispersion11while a magnetic field applied to magnetic particle dispersion11is not reinforced. This causes the entropy S of magnetic particle dispersion11to increase, whereby the characteristic point inFIG.3moves from point A to point B. Here, the temperature change profile from point A to point B depends both on the magnetocaloric effect of magnetic particles11band on the heat transfer between magnetic particle dispersion11and heat-giving fluid20. The strength of the magnetic field may be changed while moving from point A to point B. Then, the temperature change profile varies depending on how the magnetic field is changed.

Magnetic particle dispersion11that has received heat from heat-giving fluid20in heat-absorbing section12, flows through the channel to be supplied to temperature-rising section14. In temperature-rising section14, magnetic field17applied to magnetic particle dispersion11that has passed through heat-absorbing section12is reinforced. This causes the magnetic moments of magnetic particles11bto change, whereby the characteristic point inFIG.3moves from point B to point C. In this case, since the magnetic moments are changed in an adiabatic environment, the temperature T of magnetic particle dispersion11rises.

Magnetic particle dispersion11whose temperature has been raised in temperature-rising section14, flows through the channel to be supplied to heat-releasing section13. In heat-releasing section13, magnetic field17applied to magnetic particle dispersion11that has passed through temperature-rising section14is kept reinforced. This causes the entropy of magnetic particle dispersion11to decrease, whereby the characteristic point inFIG.3moves from point C to point D. In this case, magnetic particle dispersion11releases heat to heat-receiving fluid30in response to the decrease in entropy and temperature of magnetic particle dispersion11. For this case, since heat-releasing section13is located downstream of temperature-rising section14in the flow direction of magnetic particle dispersion11, the temperature of heat transferred to heat-receiving fluid30in heat-releasing section13is higher than the temperature of heat transferred from heat-giving fluid20in heat-absorbing section12. The temperature change profile from point C to point D depends both on the magnetocaloric effect of magnetic particles11band the heat transfer between magnetic particle dispersion11and heat-receiving fluid30. The strength of the magnetic field may be changed while moving from point C to point D. Then, the temperature change profile varies depending on how the magnetic field is changed.

Magnetic particle dispersion11that has released heat to heat-receiving fluid30in heat-releasing section13, flows through the channel to be supplied to temperature-dropping section15. In temperature-dropping section15, magnetic field17applied to magnetic particle dispersion11, that has been reinforced when having passed through heat-releasing section13, is reduced. This causes the magnetic moments of magnetic particle11bto change, whereby the characteristic point inFIG.3moves from point D to point A. In this case, since the magnetic moments are changed in an adiabatic environment, the temperature T of magnetic particle dispersion11drops. As a result, the temperature of magnetic particle dispersion11supplied to heat-absorbing section12after passage through temperature-dropping section15is lower than the temperature of magnetic particle dispersion11supplied to temperature-rising section14after passage through heat-absorbing section12.

Since magnetic particle dispersion11circulates through the channel as described above, it receives heat at lower temperatures and releases heat at higher temperatures.

Thus, heat pump10shown inFIG.1functions as a heat pump that uses the magnetocaloric effect to receive heat from heat-giving fluid20and release heat to heat-receiving fluid30.

A permanent magnet or an electromagnet is a possible source of magnetic field17, and in heat pump10shown inFIG.1, a permanent magnet is more preferably used in view of the fact that no power source is required.

The effect of using magnetic particle dispersion11in heat pump10shown inFIG.1will be described below.

FIG.4Ashows the heat transfer effect in a conventional configuration to illustrate the effect of using magnetic particle dispersion11in heat pump10shown inFIG.1.

FIG.4Bshows the heat transfer effect in heat pump10shown inFIG.1.

As shown inFIG.4Aa, in the heat pump disclosed in Patent Literature 1, when a magnetic field is applied while liquid working fluid111ais in contact with magnetic particles111bfilled inside the device, heat flux111cis transferred from magnetic particles111bto liquid working fluid111a. If the size of magnetic particles111bis reduced, the heat pump efficiency will decrease because the pressure drop of working fluid111ais increased. Therefore, magnetic particles111bmust be relatively large in size to prevent loss of heat efficiency. As a result, the heat transfer area formed by contact between magnetic substances111band liquid working fluid111ais reduced, and heat flux111cgenerated in magnetic substances111bis not efficiently transferred to working fluid111a.

On the other hand, in heat pump10shown inFIG.1, magnetic particle dispersion11, which is a colloidal fluid containing magnetic particles11bdispersed in dispersion medium11a, is used as the working fluid, as described above. Therefore, as shown inFIG.4B, magnetic particles11bare very small in size. As a result, the heat transfer area between magnetic particles11band dispersion medium11ais extremely large. This improves the efficiency of heat exchange between magnetic particles11band dispersion medium11a, whereby heat flux11cis transferred with high efficiency.

Thus, in this embodiment, the primary working fluid circulating between heat-absorbing section12that receives heat from heat-giving fluid20and heat-releasing section13that releases heat to heat-receiving fluid30is magnetic particle dispersion11which is a colloidal fluid containing magnetic particles11bdispersed in dispersion medium11a, and therefore the efficiency of heat exchange between magnetic particles11band dispersion medium11ais improved, enabling highly efficient heat transfer using the magnetic field.

A configuration will be described here in which heat energy is transferred with an even larger temperature difference by means of heat pump10described above.

FIG.5shows an exemplary configuration of a heat pump unit that transfers thermal energy with an even larger temperature difference by means of heat pump10shown inFIG.1.

As shown inFIG.5, this exemplary configuration includes three heat pumps10a-10ceach having the same configuration as heat pump10shown inFIG.1, and heat-transfer assisting sections40a,40beach located between two heat pumps10a-10c. These three heat pumps10a-10cand two heat-transfer assisting sections40a,40bare arranged as follows: heat pump10a, heat-transfer assisting section40a, heat pump heat-transfer assisting section40b, and heat pump10care arranged in this order from a side of the channel through which heat-giving fluid20flows, i.e. heat pump10cis located closest to the channel through which heat-receiving fluid30flows. In each of heat-transfer assisting sections40a,40b, pump42causes secondary working fluid41to flows through a channel.

In the heat pump unit configured as described above, heat is first transferred from heat-giving fluid20to magnetic particle dispersion11in heat-absorbing section12of heat pump10a, the temperature of magnetic particle dispersion11rises, and then heat is released from magnetic particle dispersion11in heat-releasing section13of heat pump10a. The heat released in heat-releasing section13of heat pump10ais transferred to secondary working fluid41of heat-transfer assisting section40alocated between heat pumps10a,10b. This heat is then transferred to magnetic particle dispersion11in heat-absorbing section12of heat pump10b.

Next, the temperature of magnetic particle dispersion11, to which heat has been transferred in heat-absorbing section12of heat pump10b, rises in heat pump10b, and thereafter heat is released in heat-releasing section13of heat pump10b. The heat released in heat-releasing section13of heat pump10bis transferred to secondary working fluid41of heat-transfer assisting section40blocated between heat pumps10b,10c. This heat is then transferred to magnetic particle dispersion11in heat-absorbing section12of heat pump10c.

Subsequently, the temperature of magnetic particle dispersion11, to which heat has been transferred in heat-absorbing section12of heat pump10c, rises in heat pump and thereafter heat is released to heat-receiving fluid30in heat-releasing section13of heat pump10c.

As described above, in the heat pump unit of this exemplary configuration, three heat pumps10a-10care arranged such that heat-absorbing section12of the heat pump in the succeeding stage receives heat released in heat-releasing section13of the heat pump in the preceding stage. In addition, heat-transfer assisting sections40a, are arranged between three heat pumps10a-10cto receive heat released in heat-releasing section13of the preceding heat pump with secondary working fluid41and to give the heat of secondary working fluid41to heat-absorbing section12of the succeeding heat pump. Thus, the temperature difference between heat to be received from heat-giving fluid20and heat to be released to heat-receiving fluid30can be further increased, allowing thermal energy to be transferred with a large temperature difference. For example, assuming that each of heat pumps10a-10ccan transfer thermal energy with a temperature difference of 10° C., and that there is no loss between magnetic particle dispersion11flowing through the channels of heat pumps10a-10cand secondary working fluid41flowing through the channels of heat-transfer assisting sections40a,40b, thermal energy can be transferred with a temperature difference of

In this exemplary configuration, the heat pump unit with three-stage structure using three heat pumps10a-10cis illustrated, but the number of heat pumps is not limited thereto. The greater the number of stages, the further the temperature difference between heat to be received from heat-giving fluid20and heat to be released to heat-receiving fluid30can be increased.

How much and in which temperature range the magnetocaloric effect causes heat release or heat absorption to occur is specific to each type of magnetic material of magnetic particles11b, and if they are made of an alloy, it varies in a complex manner depending on the composition of the alloy. For that reason, in the heat pump using the magnetocaloric effect, suitable magnetic materials generally depend on the temperature level to be applied.

Therefore, it is possible that as the magnetic material of magnetic particles11bin magnetic particle dispersion11flowing through the channels of three heat pumps10a-10cthat constitute the heat pump unit shown inFIG.5, a magnetic material that releases/absorbs large amounts of heat due to the magnetocaloric effect may be individually selected depending on the temperatures of heat to be received in heat-absorbing section12and heat to be released in heat-releasing section13of heat pumps10a-10c. For example, assume that each of heat pumps10a-10ccan transfer thermal energy at a temperature difference of 10° C., so that heat is received from heat-giving fluid20at 20° C. and released to heat-receiving fluid30at 50° C. In such a case, it is possible that as the magnetic material of magnetic particles11bin magnetic particle dispersion11flowing through the channel of heat pump10a, a magnetic material that releases/absorbs large amounts of heat due to the magnetocaloric effect at 20-30° C. may be selected, that as the magnetic material of magnetic particles11bin magnetic particle dispersion11flowing through the channel of heat pump10b, a magnetic material that releases/absorbs large amounts of heat due to the magnetocaloric effect at may be selected, and that as the magnetic material of magnetic particles11bin magnetic particle dispersion11flowing through the channel of heat pump10c, a magnetic material that releases/absorbs large amounts of heat due to the magnetocaloric effect at 40-50° C. may be selected.

Thus, if the magnetic material of magnetic particles11bin magnetic particle dispersion11in each of the multiple stages of heat pumps is individually selected depending on the temperatures of heat to be received in heat-absorbing section12and heat to be released in heat-releasing section13in each heat pump, the overall thermal efficiency can be improved.

As described above, in the configuration where heat pump10shown inFIG.1is arranged in multiple stages such that heat-absorbing section12of the heat pump in the succeeding stage receives heat released in heat-releasing section13of the heat pump in the preceding stage, and where heat-transfer assisting sections40a,40bare arranged between the multiple stages of heat pumps to receive heat released in heat-releasing section13of the heat pump in the preceding stage with secondary working fluid41and to give the heat of secondary working fluid41to heat-absorbing section12of the heat pump in the succeeding stage, the heat is transferred between magnetic particle dispersion11of heat pumps10a-10cand secondary working fluid41of heat-transfer assisting sections40a,40b. In this case, if the heat transfer between magnetic particle dispersion11and secondary working fluid41occurs not through direct contact with each other, but through the walls of the channels through which they flow, there will be a loss of heat transfer through the walls of the channels. Therefore, the temperature of magnetic particle dispersion11must be raised or lowered extra for the temperature difference caused by the loss. The larger this temperature difference, the lower the heat pump efficiency of heat exchange. On the other hand, to transfer heat between magnetic particle dispersion11and secondary working fluid41through the walls of the channels without reducing the efficiency of heat exchange, the wall materials of the channels must be expensive. In other words, an attempt to transfer heat without bringing magnetic particle dispersion11into contact with secondary working fluid41involves difficulties in terms of heat exchange efficiency and economy.

A configuration will be described below in which the economy is not compromised and the efficiency of heat exchange is reduced when heat is transferred between magnetic particle dispersion11of heat pumps10a-10cand secondary working fluid41of heat-transfer assisting sections40a,40bas shown inFIG.5.

FIG.6is a cross-sectional view of the channel of the heat pump unit shown inFIG.5, through which magnetic particle dispersion11of heat pumps10a-10cand secondary working fluid41of heat-transfer assisting sections40a,40bflow.

As shown inFIG.6, magnetic particle dispersion11and secondary working fluid41are configured to flow through common channel50with each other. In this case, if dispersion medium11aof magnetic particle dispersion11ais hydrophilic, then a hydrophobic fluid is used as secondary working fluid41, or if dispersion medium11aof magnetic particle dispersion11is hydrophobic, then a hydrophilic fluid is used as secondary working fluid41. In other words, magnetic particle dispersion11and secondary working fluid41are configured such that one of them is hydrophilic and the other is hydrophobic.

Further, for example, in the channel with a square cross section, of two sets of wall surfaces51,52, each set facing each other, one set of wall surfaces51is processed to produce a magnetic field and/or to have an affinity for the dispersion medium of the magnetic particle dispersion, while the other set of wall surfaces52is processed to have an affinity for secondary working fluid41. When magnetic particle dispersion11and secondary working fluid41flow through channel50processed as described above while a magnetic field is applied in a direction where wall surfaces51face each other, magnetic particle dispersion11and secondary working fluid41flows along wall surfaces51and wall surfaces52, respectively, with being separated from each other, due to the effects of both the magnetic force due to the magnetic field and the surface tension of the fluid, as shown inFIG.6. In this case, to allow magnetic particle dispersion11and secondary working fluid41to flow along wall surfaces51and wall surfaces52, respectively, with being separated from each other, the size of the channel must be small enough so that the magnetic force due to the magnetic field and the surface tension of the fluid are dominant over the other forces.

Since magnetic particle dispersion11and secondary working fluid41are kept separated from each other in the channel, magnetic particle dispersion11and secondary working fluid41can be easily removed with being separated from each other after the heat exchange between them, as a result of removing magnetic particle dispersion11from wall surfaces51with high affinity for it and removing secondary working fluid41from wall surfaces52with high affinity for it.

As described above, since magnetic particle dispersion11and secondary working fluid41are configured such that one of them is hydrophilic and the other is hydrophobic, magnetic particle dispersion11and secondary working fluid41can be brought into direct contact with each other inside one channel50to perform heat exchange between them. This reduces the heat transfer resistance between magnetic particle dispersion11and secondary working fluid41, allowing efficient heat exchange with a temperature difference as close to “0” as possible. Further, since magnetic particle dispersion11and secondary working fluid41are configured such that one of them is hydrophilic and the other is hydrophobic, magnetic particle dispersion11and secondary working fluid41can be easily removed with being separated from each other after the heat exchange between them. In addition, in each of the multiple stages of heat pumps, heat exchange between magnetic particle dispersion11and secondary working fluid41of the heat-transfer assisting section is performed as described above, which can realize a configuration that reduces as much as possible the loss associated with the temperature difference required for the heat exchange between magnetic particle dispersion11and secondary working fluid41.

REFERENCE SIGNS LIST