Field of the invention

The present invention relates to a heat pump system in accordance with the preamble of claim 1. Also, the present invention relates to a method for heat pumping.

Prior art

Heat pump systems serve to transport thermal energy from a low temperature medium to a higher temperature medium. Typically, such heat pumps are used for retrieving residual heat from an effluent, for example, a water flow used for cooling or in general a flow of heated water. Typically, the thermal energy contained in the effluent is retrieved (in part) by a heat exchanger system where the effluent flow heats a secondary, relatively colder (water) flow. In such a system, effluents containing contaminating substance may reduce the efficiency of the heat exchanger due to a blockage. For example, water containing a contaminant may adversely affect a direct heat exchange between the effluent flow and the secondary flow due to deposition of the contaminant on the exchanger. For example, soap-like substances in water render direct heat exchange substantially impracticable.

Due to possible contamination of the water, retrieval of energy by a heat exchanger is often carried out in a flash-evaporating tank. In such a flash-evaporation tank a relatively low pressure is maintained and when the effluent is introduced, the liquid evaporates (flashes) due to the relative low pressure. By the evaporation step, the vapor and liquid cool down.

The vapor in the flash-evaporation tank is brought into contact with an evaporator

(i.e. a heat exchanger), where the vapor condenses into a liquid. At the same time, the thermal energy that is released in the condensing step is taken up by a secondary flow in the evaporator. The secondary flow may be transferred by a pump to another location, where the absorbed thermal energy is released.

It is noted that the reduction of the pressure in the flash-evaporation tank is such that the effluent evaporates, that is to say, is at its boiling point. The boiling temperature is below the temperature of the effluent when entering the flash-evaporation tank (at normal pressure).

Further, the pumping labor to reduce the pressure in the tank and to remove the vapor (at low pressure) to ambient pressure is inefficient. For these reasons, the practical feasibility of heat exchange by use of a flash-evaporation tank is low.

In the prior art, the flash-evaporation concept is enhanced by dividing the flash- evaporation tank in a first volume where the flashing of the effluent takes place and vapor is produced, and a second volume where the vapor releases its thermal energy in a contact with the secondary flow (directly or by means of a heat exchanger) and condenses again. The released thermal energy is transported by the secondary flow to another location. The vapor in the first volume is at a first pressure where the liquid of the effluent is boiling. In the second volume the vapor is at a second pressure which is preferably higher than the first pressure. For transport of the vapor from the first volume to the second volume it is noted that typically a large compressor is needed since due to the vacuum, the amount of vapor to be transported is large and the ratio of second pressure over first pressure is also large.

From the prior art, heat pump systems with a suitable compressor such as a radial or axial compressor are known but disadvantageous^ the cost of such a compressor is often prohibitive for application.

As an alternative for such a compressor, a steam jet pump is known which has an inlet which is connected to the first volume for a flow of the vapor from the first volume, an outlet to the second volume for transport of the flow from the first volume, and a second inlet which is arranged to take up a flow of steam. The flow of steam is used to power the flow of the vapor from the first to the second volume.

Disadvantageously, the steam jet pump is not very efficient to power the vapor flow from first to second volume. For practical vapor flows for example of water vapor at a first pressure at a flashing temperature of, say, 1O ⁰ C and condensing at a second pressure at a temperature of, say, 50 ⁰ C, the flow of steam must be a multiple of the vapor flow to be transported. Clearly, the energy needed to produce steam for the jet pump will be relatively high, and under these conditions the efficiency of such a steam jet pump is too low for the purpose of retrieval of thermal energy.

Summary of the invention

It is an object of the present invention to provide a heat pump system which can efficiently be used for retrieval of thermal energy from a fluidum such as an effluent.

The object is achieved by a heat pump system as defined in the preamble of claim 1, characterised in that the compressor comprises a two-phase jet pump for compressing a vapour by means of impulse-retrieval out of an expanding liquid; the two-phase jet pump having:

• a first inlet connected to the first volume,

• an outlet connected to the second volume, and • a second inlet for a fluidum for driving the two-phase-jet pump, wherein, in use, the flow of fluidum is introduced into the second inlet of the two- phase-jet pump.

Advantageously, such a two-phase-jet pump uses the flow of effluent liquid to drive the compressing and transport of the vapor. It is not needed to provide an external power source.

Moreover, the liquid jet of the two-phase jet pump is more efficient in dragging the vapor from the first volume than a steam jet.

By the transport of the vapor from the first volume at the first pressure to the second volume at the second pressure, thermal energy (enthalpy) is transferred from the first volume at the first temperature to the second volume at the second temperature. Also, the present invention relates to a method for heat pumping as defined in the preamble of claim 21, characterised in that the transporting of vapor comprises the step of:

- compressing said vapor by a two-phase-jet pump, the two-phase jet pump having:

• a first inlet connected to the first volume,

• an outlet connected to the second volume, and

• a second inlet for a fluidum for driving the two-phase-jet pump, by introducing the flow of fluidum into the second inlet of the two-phase-jet pump.

Brief description of drawings

Below, the invention will be explained with reference to some drawings, which are intended for illustration purposes only and not to limit the scope of protection as defined in the accompanying claims. Figure 1 shows a heat pump system from the prior art;

Figure 2 shows a heat pump system according to the present invention; Figure 3 shows a jet pump;

Figure 4 shows the heat pump system in a first embodiment; Figure 5 shows the heat pump system in a second embodiment; Figure 6 shows the heat pump system in a third embodiment; Figure 7 shows a fourth embodiment of the heat pump system; Figure 8 shows a fifth embodiment of the present invention, and Figure 9 shows a sixth embodiment of the heat pump system of the present invention.

Description of embodiments Figure 1 shows a heat pump system from the prior art. A flash-evaporation tank 1 comprises a first volume Vl and a second volume V2, which are separated from each other by a wall W. Alternatively, the first and second volumes Vl, V2 may be separate tanks.

The first volume Vl comprises an inlet Il where an effluent flow Fl of a fluidum may be introduced. The first volume Vl is further connected at an outlet Ol to a compressor unit CP. The compressor unit CP is further connected to a second inlet 12 of the second volume V2. The compressor unit CP may comprise a radial or axial compressor (or turbine) or a steam jet pump.

In the second volume V2 a heat exchanger HX is arranged, through which in use a secondary flow F2 streams.

Further, a by-pass duct BP connects a portion of the second volume V2 which is arranged for holding liquid, to the first volume Vl .

During use, a first pressure Pl is maintained in the first volume Vl. The effluent Fl which holds residual heat and has a temperature Tr, flows into the first volume Vl. Upon introduction in the first volume Vl at the first pressure Pl, a part of the effluent flashes to a vapor VPl . The first pressure Pl is chosen in such a way that the effluent evaporates, that is to say, is at its boiling point (or above). The boiling

temperature Tl corresponding to the chosen first pressure Pl is below the temperature Tr of the effluent when entering the first volume Vl (at normal pressure). At the bottom of the first volume Vl, remaining boiling liquid Ll is collected. Through a second outlet 02, the liquid Ll at substantially temperature Tl (Tl < Tr) can be removed (for example, for cooling or in general when a certain level is reached within the first volume Vl).

The compressor unit CP takes the vapor VPl in a first vapor flow VFl from the first volume Vl and transports the vapor in a second vapor flow VF2 to the second volume V2. The second vapor VP2 in the second volume V2 is at a second pressure P2. Under these conditions, the second vapor V2 is (substantially) saturated. The second pressure P2 corresponds to a second temperature T2 at which the second vapor V2 will condense. During use of the heat pump system the secondary flow F2 takes up heat from the condensing second vapor VP2. Depending on the actual uptake of heat, the condensation rate of the second vapor VP2 and the input of new vapor by the compressor unit CP, a steady state pressure P2 is created, or in other words, the second pressure P2 is thus maintained by a self-regulation.

However, since under non-ideal conditions some non-condensing gases may be introduced in the system, which may affect the pressure in the second volume V2, a second compressor unit (indicated by arrow CP2) may be arranged at a third outlet 03 of the second volume V2.

In the second volume V2 the second vapor VP2 is in contact with the heat exchanger HX. Through the heat exchanger HX a secondary flow F2 is maintained which enters at a relatively low exchanger inlet temperature TL. The exchanger inlet temperature TL is below the second temperature T2 at which the second vapor condenses: The second vapor VP2 releases its thermal energy in a contact with the heat exchanger. The released thermal energy is absorbed by the secondary flow F2 and transported to another location. Due the absorption of the thermal energy, the secondary flow F2 at the outlet of the heat exchanger HX has a relatively high exchanger outlet temperature TH compared to the inlet temperature TL. A net transport of heat Q from the second volume V2 is thus obtained.

During the condensation a second liquid L2 is formed in the second volume V2. Through by-pass duct BP, which is provided with a valve, the second liquid L2 can be removed.

Since the second liquid L2 has (at least in approximation) the second temperature T2 (higher than the first temperature Tl in the first volume Vl), the second liquid may be transferred to the first volume Vl to serve as a further feed flow.

For transport of the first vapor VPl from the first volume Vl to the second volume V2 it is noted that the compressor unit CP comprises typically a large compressor since due to condition of a vacuum, the amount of vapor to be transported is large and the ratio of second pressure P2 over first pressure P 1 is also relatively large.

As an alternative for such a compressor, the compressor unit CP may comprise a steam jet pump, where a flow of steam is used to power the first vapor flow VFl from the first volume Vl to the second vapor flow VF2 towards the second volume V2.

Figure 2 shows a heat pump system 10 according to the present invention. The present invention recognizes the fact that for some conditions for example, where a relatively small mass flow Fl of effluent (fluidum) and/or relatively small energy flow Q (with a relatively small ratio of exchanger inlet and outlet temperatures TL and TH) exists, the use of a (turbine) compressor or a steam jet pump can not be reasonably efficient. For example this may occur where heat must be retrieved from the effluent water from a shower or a bath. Typically, the effluent water has a temperature of about 35 ⁰ C, the flow of fresh water to be heated (thus secondary flow F2) has an inlet temperature of about 1O ⁰ C, and a required outlet temperature of about 40 ⁰ C. The flow F2 will typically be about 10 liters per minute. These conditions do not allow efficient application of a heat pump system from the prior art.

Nonetheless, the following description will illustrate that the heat pump system of the present invention is not limited to "small-scale" system applications, but may be scaled for larger mass flow or energy flow applications.

In Figure 2 entities with the same reference number refer to identical entities as shown in the preceding figures.

The heat pump system 10 according to the present invention comprises a first volume Vl and a second volume V2 similar to the heat pump system 1 of the prior art.

The functionality as described above with reference to Figure 1 is similar.

In the heat pump system 10 of the present invention, the transfer of the first vapor flow VFl to the second vapor flow VF2 is driven by a two-phase jet pump TPE, which advantageously applies the flow of effluent Fl as a power source for the pumping action. The flow of effluent Fl may be generated by a pump (not shown) or by use of gravity.

Please note that the effluent or fluidum in the flow Fl may be a liquid or a two- phase mixture of liquid and vapor, or a vapor.

In the two phase jet pump TPE, the impulse from the effluent flow Fl is used to drag the first vapor VPl along the flow to the second vapor VP2 in the second volume V2. An example of a two phase jet pump is shown in Figure 3.

Such a two-phase-jet pump TPE comprises a first inlet or vapor inlet VN for receiving a vapor flow such as the first vapor flow VFl of the first vapor VPl from the first volume Vl, a second inlet or fluid inlet FN for receiving a driving liquid flow such as the effluent flow Fl, and an outlet for a two phase flow TPN for outputting a combination flow VF2 ' of the vapor flow VF 1 and the driving liquid flow F 1.

Within the two-phase jet pump TPE, the fluid inlet FN is connected to a nozzle NZ, which has a smaller throughput opening than the fluid inlet FN. The nozzle NZ is arranged for discharge in an inlet section INS, which also connects to the vapor inlet VN. Further, the two phase jet pump TPE comprises an mixing chamber MX and a diffuser DF. The mixing chamber MX is directly adjacent to the inlet section INS and is arranged for mixing the driving liquid flow from the fluid inlet FN and the vapor from the vapor inlet. The diffuser DF is located downstream between the mixing chamber MX and the two phase outlet TPN.

When, in use, the flow Fl enters the nozzle NZ through the second inlet FN with a given (overpressure and temperature, ^" and expands. Due to the (preservation of) impulse, in the inlet section INS at the exit of the nozzle NZ locally a reduced pressure exists which transports vapor VPl through the vapor nozzle VN into the inlet section INS, and subsequently through the mixing chamber MX and the diffuser DF to the two phase nozzle TPN as secondary vapor+liquid flow VF2'. The secondary vapor+liquid flow VF2' exits the two-phase jet pump TPE at outlet nozzle TPN, which is connected by a pipeline to an inlet of the second volume V2.

The overpressure of the liquid Fl entering the nozzle NZ indicates that the effluent flow Fl has a higher pressure PL than the second pressure P2 in the second volume V2: PL > P2.

In the second volume V2, a separation of a second vapor VP2 and a second liquid L2 from the secondary vapor+liquid flow VF2' takes place.

Advantageously, the two phase jet pump TPE uses the flow Fl of the effluent liquid entering on the second inlet or fluid inlet FN to drive the pumping and transport of first vapor VPl to second vapor VP2. It is not needed to provide an additional external power source. Moreover, the liquid inlet jet of the two-phase jet pump TPE is more efficient in dragging the vapor VPl from the first volume Vl than a steam jet would do due to the momentum carried by the flowing liquid in comparison to the momentum carried by a vapor or gas.

By the transport of the first vapor VPl from the first volume Vl at the first pressure Pl to the second vapor VP2 in the second volume V2 at the second pressure P2, thermal energy (enthalpy) is transferred from the first volume Vl to the second volume V2.

Referring back to Figure 2, it is noted that the effluent flow Fl now enters the second volume V2 partially as second liquid L2. From the second volume V2, the second liquid L2 reaches the first volume Vl through by-pass duct BP. Effluent liquid does not enter directly into the first volume Vl .

In some embodiments, the by-pass duct BP may controlled by a float in the second volume V2 in response to a level of the second liquid L2.

A surplus of the first liquid Ll in the first volume Vl may be removed through second outlet 02.

For removal of non-condensing gases from the second volume V2, at the third outlet 03 the second compressor unit CP2 may be connected to the second volume V2.

Figure 4 shows the heat pump system in a first embodiment.

In Figure 4 entities with the same reference number refer to identical entities as shown in the preceding figures.

Second outlet 02 on the first volume Vl is connected by a pipeline PLl to a second pump unit PU2. The second pump unit PU2 removes the first liquid Ll from the first volume Vl at first pressure Pl and brings the pumped-off liquid to substantially

ambient pressure. It is noted that a sensor (not shown) for sensing a level of the first liquid Ll in the first volume Vl may be provided for controlling the action of the second pump unit PU2.

In the downstream of the second pump unit PU2 pipeline PL2 transports the pumped-off liquid to a liquid jet pump PU3. The liquid pumped-off by the second pump unit PU2 is used for driving the liquid jet pump PU3. A second inlet of the liquid jet pump PU3 is further connected to the third outlet on the second volume V2 by a third pipeline PL3.

When driven by the pumped-off liquid the liquid jet pump PU3 is capable of removal of non-condensing gases from the second volume V2.

An outlet of the liquid jet pump PU3 is connected by a fourth pipeline PL4 to a drain 04 for removal of the pumped-off liquid from the first volume Vl and the pumped-off vapor from the second volume V2.

It is noted that within each of the pipelines PLl, PL2, PL3, PL4 a one-way valve (not shown) may be located to avoid inflow of gas from ambient to the volumes Vl, V2 at their respective lower pressure.

An example in which the embodiment of Figure 4 can be applied is a heat retrieval system for a shower. Typically, the effluent water of a shower may have a temperature of 35°C. The temperature of hot fresh water to be provided at the shower will be about 4O ⁰ C. The temperature of the fresh water before heating is approximately 1O ⁰ C. The fresh water flow is represented by the secondary flow F2, that passes the heat exchanger HX. By absorbing condensation heat from the second vapor VP2, the temperature of the second flow F2 must be raised from TL = about 10 ⁰ C to TH = about 40 ⁰ C. The first pressure in the first volume Vl (the flashing tank) is set to about 850 Pa, which corresponds to a boiling temperature of water (Ll) of about 5°C.

The second pressure in the second volume V2 is set to about 9500 Pa, which corresponds to a boiling/condensation temperature of water (VP2, L2) of about 45 ⁰ C.

The effluent flow Fl is typically about 10 liters/min. As known to persons skilled in the art, the efficiency of other thermal systems such as heat-pumps (intended for cooling and/or heating) in general, heat recovery-systems, heat transport-systems may be improved as well by lifting and/or reducing the

temperature-level by means of retrieval of residual heat from the return flow Fl of such other thermal system.

The heat pump system according to the embodiment shown in Figure 4 can be used for heat retrieval in a shower. This heat pump system may be extended with a drip pan DRP.

In the drip pan DRP, during operation a dripping condensate of the condenser HX can be accumulated. From this drip pan DRP, the clean condensate is drained and expanded into an evaporator EV positioned above a shower (thus, in operation, in a flow SV of warm moisturized air generated by the shower). The evaporator EV has an outlet connected to the first volume Vl. During operation, evaporating liquid in the evaporator, will cause by its expansion and cooling moisture formed in the shower to condensate, thus the evaporating liquid may take up condensation heat from the moisture in the shower. Next, the evaporating liquid is thus returned to the first volume (and adds the retrieved condensation heat from the shower to the flow Fl). In this manner the heat-retrieval efficiency of the heat pump system is increased. Note that the extension of the heat pump system by drip pan DRP and evaporator EV is not limited to a shower but may also be applicable in a similar system that generates a flow of relatively warm moisture or heat at higher temperature level than temperature Tl . Please note that the drip pan DRP and evaporator EV can also be applied in the embodiments of figures 5 and 6 as will be described below. For reason of clarity the configuration of the drip pan DRP and the evaporator EV is only shown in Figure 4. Figure 5 shows the heat pump system in a second embodiment. In Figure 5 entities with the same reference number refer to identical entities as shown in the preceding figures. The maintenance of the second pressure P2 can be advantageously driven by the secondary flow F2 through the heat exchanger HX.

The third outlet 03 on the second volume V2 is connected by a fifth pipeline PL5 to an inlet of a fourth pump unit PU4. The fourth pump unit PU4 may be a liquid jet pump. The fourth pump unit PU4 has a second inlet which is connected to the outlet of the heat exchanger HX for receiving the secondary flow F2 that leaves the heat exchanger HX. The secondary flow F2 is used for driving the action of the fourth pump unit PU4.

Again, a one-way valve (not shown) may be arranged in the fifth pipeline PL5 to avoid backflow from the pipeline to the second volume V2.

The second embodiment may be preferred in circumstances where the secondary flow F2 is allowed to comprise gaseous components. Figure 6 shows the heat pump system in a third embodiment.

In Figure 6 entities with the same reference number refer to identical entities as shown in the preceding figures.

In the third embodiment, a pulsation pump system is used for pumping the first liquid Ll from the first volume Vl . The heat pump system in the third embodiment comprises a third volume V3 which is in connection to the first volume Vl through the second outlet 02.

In the second outlet 02, a cut-off valve CVl is arranged for cutting off the flow of the first liquid Ll to the third volume V3.

By the connection of the cut-off valve CVl, the first liquid Ll can flow to the third volume V3. Typically, the cut-off valve CVl comprised a float FT which closes the cut-off valve CVl when a level of liquid L3 in the third volume reaches a predetermined maximum level.

The third volume comprises an outlet for liquid 05 and an outlet for gas 07.

Outlet for liquid 05 is arranged as a one-way valve CV4, which opens only if the pressure P3 of the third volume is at substantially ambient pressure. At lower pressure P3 of the third volume V3 the outlet for liquid 05 is closed. The outlet for liquid 05 is connected to a drain 06 for discharge of liquid L3 collected in the third volume V3.

Similar as shown in Figure 5, a liquid jet pump PU4 is arranged to pump non- condensing gas from the second volume V2 using the secondary flow F2 through the heat exchanger HX as driving force. The second volume V2 is connected to the liquid jet pump PU4 by pipeline PL6 over a one-way valve CV2. Furthermore, the gas outlet 07 of the third volume V3 is also connected to the liquid jet pump PU4.

At the third volume V3 a gas inlet 13 is arranged. The gas inlet 13 comprises a controllable valve CV3 and a level sensor LS. The controllable valve CV3 is connected on one side to a third inlet of the third volume V3 and at another side is contact with ambient or a gas. The level sensor LS is connected to the first volume Vl for sensing a level of the first liquid Ll. The controllable valve CV3 is arranged for receiving a level signal from the level sensor LS. The level signal from the level sensor LS is used for

controlling the open or closed state of the controllable valve CV3. If the controllable valve CV3 is open, ambient or gas is allowed to flow into the third volume V3. If the gas inlet 13 uses a gas then the external pressure of the gas is selected to be above the pressure at the outlet 05. During use, liquid jet pump PU4 transports non-condensing gas from the second volume V2 and simultaneously reduces a pressure P3 in the third volume V3, typically to a substantially same pressure level as in the second volume V2.

Due to the third pressure P3 being lower than the ambient pressure, the outlet for liquid 05 is closed. Since the third pressure P3 is still higher than the first pressure Pl in the first volume Vl, the cut-off valve CVl will be closed until the liquid column has reached such a level that the pressure exerted by the first liquid Ll opens the cut-off valve CVl to let the first liquid Ll enter into the third volume V3.

If during use, inside the third volume V3, the level of liquid L3 is at a predetermined maximum, the valve CVl will be closed by the upward fore of the liquid L3 in the third volume V3. Now, the level of the first liquid Ll will start rising further. When the level of the first liquid Ll reaches a predetermined level sensed by the level sensor LS, the level sensor LS will provide a signal to the controllable valve CV3 to open. By pressurizing to ambient pressure, the outlet for liquid 05 is enabled to open, and the cut-off valve CVl stays closed due to overpressure. The level of liquid L3 in the third volume V3 will fall until it reaches a low level which is sensed by a second level sensor LS2. When this point is reached the controllable valve CV3 is controlled to close. The pressure in the third volume V3 is reduced again by the liquid jet pump PU4. The cycle can now repeat itself. Due to the discontinuous nature of the pumping action, this type of pumping is often referred as a pump in a pulsating mode. ^' It is rioted that the one-way valve CV2 between the second volume V2 and the pipeline PL6 is arranged to prevent pressurizing of the second volume V2 during inflow of gas in the third volume by controllable valve CV3.

Figure 7 shows a fourth embodiment of the heat pump system of the present invention. In Figure 7 entities with the same reference number refer to identical entities as shown in the preceding figures.

In this embodiment, the heat exchanger HX in the second volume V2 is replaced by a spraying unit SU. The second volume V2 is connected at an outlet 08 to a pump PU

which is arranged to transport the second liquid L2 from the second volume V2 to a cooling unit CU. From the cooling unit CU the liquid L2 after being cooled is returned to the second volume through the spraying unit SU. In the spraying unit SU the cooled liquid L2 is sprayed as spray L2' into the second volume V2. The first liquid Ll in the first volume Vl under first pressure Pl is under flashing conditions, i.e. is cooling and has a relatively low temperature, in approximation equal to the flashing temperature for the substance at Pl . From the first volume a flow Fl ' of the first liquid Ll is transported (by a pump or by use of gravity) to a user location UL where the first liquid Ll is used for cooling. Note that the cooling may be carried out in either an open or a closed cooling system. The return flow Fl (at pressure PL > P2) of the first liquid which has absorbed thermal energy (i.e. is relatively warm) is used to drive the two-phase jet pump TPE.

In this embodiment, the heat pump system acts as cooling device for the user location UL. On the second volume V2, a further outlet for gas removal 03 may be provided to allow the removal of non-condensing gases such as air by a compressor CP2. It is noted that such a further outlet for gas removal may be provided in other embodiments as well.

Figure 8 shows a fifth embodiment of the heat pump system of the present invention.

In Figure 8 entities with the same reference number refer to identical entities as shown in the preceding figures.

Again, in this embodiment the heat pump system acts as cooling device for a user location UL. Here the second volume V2 functions as a separator / buffer. At the third outlet 03, the second volume V2 is connected to an inlet of a compressor unit CP2. An outlet of the compressor unit CP2 is connected to an inlet of a cooling machine condensor volume CMC. The cooling machine condensor volume CMC has an outlet which is connected to an inlet of a condensation vessel CVoI. At an outlet, the condensation vessel CVoI is connected to (an inlet of) the second volume V2.

Within the cooling machine condensor volume CMC a heat exchanger HX, as described earlier, is arranged for heating a secondary flow F2.

During use, the second vapor VP2 is transported by the pump PU to the cooling machine condensation unit CVoI. The second vapor VP2 condenses on the heat exchanger HX and transfers its condensation heat to the secondary flow F2.

The condensed liquid is collected in the condensation vessel CVoI. Typically, the condensation vessel CVoI comprises a float to regulate a return flow Fr of liquid to the second volume V2. The float is constructed to prevent uptake of vapor and/or gas from the cooling machine condensor unit CMC in the return flow Fr.

Figure 9 shows a sixth embodiment of the heat pump system of the present invention. In Figure 9 entities with the same reference number refer to identical entities as shown in the preceding figures.

Again, in this embodiment the heat pump system acts as cooling device for a user location UL.

In the first volume Vl, a second heat exchanger HX2 is arranged for cooling a third flow F3+, F3-, which from the user location UL enters at a relatively high temperature (indicated as F3+) and exits at a relatively low temperature (indicated as F3-). The third flow F3 thus comprises a heat flow Q2, which is absorbed by the flashing first liquid Ll.

The transport of the first vapor VPl from the first volume Vl to form the second vapor VP2 in the second volume V2 is, in this embodiment, driven in the two-phase jet pump TPE by a flow Fl from the first liquid Ll, which is pumped by a pump PU to the two-phase jet pump TPE.

The thermal energy absorbed from heat flow Q2, is gathered in the second volume V2. The heat exchanger HX removes the thermal energy from the heat pump system to some other location (not shown).

It is noted that the heat pump system as described above can be used in various temperature ranges depending on thermodynamic properties of the effluent medium holding the residual heat, such as the effluent medium's boiling and condensation temperatures as a function of vapor pressure and the enthalpy needed for the phase transition between liquid phase and vapor phase. Media suitable as effluent medium are various.

In principle, all condensable gases, where the pressure-difference P2-P1 between the second pressure P2 and the first pressure Pl at a required temperature complies to the following relation δp ^r pump

P, - P, ⁼ liquid \ 2 1.

-t- 1

^ejector (eq.l)

may be applied in the heat pump system according to the present invention.

In eq. 1 Cpi, _qu ι _d is the specific heat of liquid, r is the evaporation heat of liquid, ηe _j ec _to ris the efficiency of the two phase jet pump TPE (maximally about 0,3), and δppump is the pressure head of the pump (usually between 2 and 4 bar or 202.65 - 405.3O kPa).

Next to water, media that may fulfil these requirements may for example be ammonia, hydrocarbons such as propane , carbon-dioxide, and halogen-carbons such as freon compounds. Other media may for example be chosen from table 1 in the ASHRAE-Handbook Chapter 18: Fundamentals (Refrigerants), F 18, (1997). Therefore, cooling systems working at low temperature (below freezing temperature of water) may also be embodied according to the present invention.

Furthermore, the heat pump system of the present invention may be arranged in a cascade with a water-cooled condensor of a heating/cooling machine or a compressor to improve the overall efficiency of the cascade.