DESCRIPTION

The invention falls within the general field of heat pump units with water exchangers and is particularly, though not exclusively, suitable for the implementation of WLHP (Water Loop Heat Pump) air conditioning systems. In the following text the term “water exchanger” is intended to mean a refrigerant gas/water heat exchange coil in a heat pump whose remaining heat exchange coil is of any type, e.g. air exchange. Normally this is the condensation exchanger when the pump is operating in cooling mode and the evaporation exchanger when the pump is operating in heating mode.

WLHP systems are based on the use of autonomous heat pump units connected by a water loop (primary circuit) that acts as a low/medium temperature heat source in both the winter heating and summer cooling cycles. The water loop system is particularly suitable when groundwater is available, the temperature of which remains remarkably constant throughout the year at values that allow easy heat exchange with the individual units, or when other low-cost energy sources are available, such as heat pumps operating around room temperature, evaporation towers, geothermal sources, or solar thermal panels. With high heat inputs through the primary circuit at a temperature generally comprised between 10 and 30°C, it is possible to make very good use of the pipes in a building for the traditional radiator heating installation by replacing the radiators with heat pump units that exchange thermal energy with the liquid circulating in the primary circuit, thus obtaining an advantageous installation valid for both summer cooling and winter heating with a very cost-effective energy advantage and with the possibility of independently regulating each of the heat pump units in the installation.

The system is particularly suitable for users such as apartment blocks, offices, hotels and shopping centres, especially if they already have a radiator heating installation, which in this case can be easily converted to achieve high energy savings. With temperatures in the order of 10-30 °C, the water circulating in the primary circuit does not indeed cause problems of condensation on the walls or excessive heat loss, making as a matter of fact this type of installation very cost- effective for the energy conversion of buildings.

In such installations the problem of collecting and disposing of condensate water produced in the evaporative units as a result of low- temperature cooling of moist air is a major issue.

Condensate water resulting from the condensation of water vapour in the air is usually evacuated by gravity or by lifting systems (pumps) to specially designed drainage systems. It is also known, for example in some technical applications (also proposed by the Applicant) in which air/gas finned condensers are used, to evaporate or nebulize the condensate water at or near the heat exchange coil which acts as a condenser. However, in many cases, this operation implies high energy consumption or, in other cases, is only feasible for some particular types of air conditioners (generally where air is used for heat transfer to the outside).

The invention is instead suitable for equipping heat pump units with a water exchanger and is particularly, though not exclusively, suitable for realizing WLHP water loop air conditioning systems. Preferably, the invention is suitable for equipping systems that use air conditioners also with reverse cycle heat pumps, by connecting them to the plumbing networks of existing heating systems (generally with radiators inside the rooms) to replace the radiators themselves. The heat exchange takes place through the water exchanger of the units with the water circulating in the primary circuit of the water loop. In turn, this heat is evacuated (when individual air conditioners cool the rooms) or regenerated (when they heat the rooms) by centralized machines, mainly reversible cycle heat pumps, evaporation towers, geothermal sources or solar thermal panels.

In these systems, the hydraulic connection of the individual air- conditioning units (or system terminals) is made via two connections for the inlet and outlet of water from the heat exchanger, similar to the connection made for heating radiators or radiator units. It becomes very advantageous to use the same existing pipes (e.g. of radiators) in order to connect the air conditioners (summer air conditioners/winter heat pumps). This avoids heavy masonry and plumbing work with high costs for energy upgrading of buildings and for integrating a summer air conditioning system without additional installations.

In these well-known systems (known as existing loop systems), the collection and removal of condensate water requires the additional installation of a special drainage pipe. In most cases, such piping may imply major works (masking of these new pipes, masonry work to create traces in walls or drill holes, plumbing works to connect these drainage pipes to the existing drainage network).

Some examples of heat pump units are described in CN 105605712 A or WO 2016/051336 Al.

The technical problem addressed and solved by the present invention is to provide a heat pump unit with a water exchanger which is structurally and functionally designed to at least partially obviate one or more of the drawbacks complained of with reference to the above- mentioned known technique. In this context, it is an aim of the present invention to eliminate the installation problems related to the disposal of condensate water generated by heat pump units.

In an example embodiment, a heat pump unit comprises a first water/gas exchanger and a second exchanger, preferably of the gas/air type, but which could also be replaced with different exchangers, e.g. gas/diathermic fluid subsequently used for air exchange, preferably a water side circuit of the first exchanger with a water inlet pipe and a water outlet pipe, preferably a condensate collector from the second exchanger and preferably a condensate discharge device from the condensate collector, preferably characterized in that said condensate discharge device comprises a condensate water pumping system whose delivery is connected to the water-side circuit of the first exchanger to discharge the condensate water through the water-side circuit of the first exchanger.

In this way, the discharge of the condensate water is performed using the existing piping, which is particularly advantageous when the heat pump unit has the water-side circuit of the first exchanger connected to the water loop of a water loop system. In a preferred embodiment, the pumping system includes a pump chosen from among those of the peristaltic, centrifugal, rotary or vibratory type. These pumps combine structural simplicity and low cost with a flow/head characteristic curve suitable for handling the low flow rates typical of a unit of this type by counteracting the pressure set in the primary water loop circuit.

In an example embodiment, the discharge device includes a condensate water collector positioned below the second exchanger and a condensate discharge pipe which extends between the collector and the water side of the first exchanger. In this way, the entire condensate water discharge circuit can be integrated into the structure of the heat pump unit, making it totally autonomous and particularly easy to install.

It is also envisaged that the disposal device includes, instead of or in addition to the pump, an ejector, in particular a constriction ejector, e.g. a Venturi effect or Coanda effect ejector, which is preferably positioned along the water side and in the constriction of which the condensate discharge pipe is preferably coupled. It should be noted that, in this context, “constriction” (or “throat”) means a narrowing and, more precisely, a localized reduction of the passage section of the ejector configured to accelerate the flow through it.

In another preferred example, the condensate discharge pump is coupled along the condensate discharge pipe. In such a case, it is preferable to insert a one-way valve (non-return valve) open in the direction of flow from the collector to the water side of the first exchanger along this condensate discharge pipe.

The unit thus defined is suitable and mainly intended to equip water loop installations. In this context, the water side of the first exchanger is connected to the installation. Advantageously, the water loop installation includes at least one heat pump unit. According to a further advantageous aspect, the water loop installation comprises a primary circuit including a heat inlet and a heat outlet and to which the water side of the first heat exchanger is preferably connected so that the condensate water of the second heat exchanger is injected into said primary circuit.

Preferably, in the water loop installation a pressure limiter is provided in the primary circuit to compensate for the supply of condensate water by partially draining the primary circuit. This allows unlimited discharge of condensate water formed at individual units and remote disposal by discharging it from the primary circuit into easily accessible drains.

The primary circuit of the water loop installation has a delivery branch and a return branch and the first exchanger of each unit is connected at the inlet to the delivery branch and at the outlet to the return branch, so that the exchangers are preferably placed in parallel with the primary circuit. In existing loop systems, the same delivery and return branches that originally performed the same function can be used to collect delivery and return from radiator exchangers (radiators).

It is envisaged that several units may be connected in series to each other and that the units or series of units may in turn be connected in parallel to each other via said primary circuit. The system with the supply of the individual heat pump units (and more precisely the water-cooling exchangers of said units) in parallel has greater simplicity in regulating the correct water flow rates of the loop. With the solution involving several units connected in series, the water flow rates on the loop are more complex to regulate.

Finally, part of the invention is a method for discharging condensate water in a heat pump unit including a first exchanger arranged to operate as a water/gas condenser and a second exchanger arranged to operate as a gas/air evaporator, a circuit of the water side of the first exchanger with a water inlet pipe and a water outlet pipe, wherein the condensate water generated by said unit is discharged by injecting it into the water side of the first exchanger.

The above method in a water loop type installation with a primary circuit to which the water side of each heat pump unit is connected ensures that condensate water can be removed from each unit through the primary circuit.

The features and advantages of the invention will become clearer from the following detailed description of a preferred but not exclusive example of a heat pump unit, related water loop installation and method of operational use illustrated, by way of non-limiting example, with reference to the enclosed drawings wherein:

- Fig. 1 is a front perspective view of a heat pump unit according to the invention;

- Fig. 2 is an enlarged scale detail of Fig. 1; - Fig. 3 is a schematic view of a building with a water loop heating and cooling installation;

- Fig. 4 shows the same building as in Figure 3 equipped for domestic water supply;

- Fig. 5 is a circuit diagram of the unit in Figures 1 and 2. The figures illustrate a building 1 with a plurality of rooms 2, e.g. a plurality of dwellings consisting in turn of multiple compartments not individually represented for simplification of the drawing. For example, it is conceivable that each compartment is schematically identical to each room 2. The building also includes a technical compartment 3 in which a thermal generator 4 is installed, for example a heat pump, a groundwater pumping system, a cooling tower possibly combined with a solar thermal heater or the like. The heat generator 4 is connected to a primary water loop circuit 5, for example the typical existing or purpose-built primary circuit used to circulate hot water in a radiator heating system.

In the primary circuit 5 there is a delivery branch 6 and a return branch 7 from which the respective delivery and return manifolds 8,9 branch off.

Inlet pipelines 10 and outlet pipelines 11 of a first heat exchanger 12 belonging to a heat pump unit 13 are connected to the manifolds 8,9. The first exchanger 12 is a water exchanger and more specifically a water/refrigerant gas exchanger. The example shows a plate heat exchanger, but it is understood that different types of heat exchangers can be used, e.g. tube bundle or other heat exchangers known in the specific sector.

The heat pump unit 13 also includes a second exchanger 14, for example of the refrigerant gas/air type, preferably a finned coil exchanger. A fan 15 presides over the forced air conveyance on the coil of the second exchanger 14; a condensate water collector 16 is placed below the second exchanger 14 to collect the condensate generated on the coil of the second exchanger. The unit 13 further comprises a compressor 17 of the refrigerant gas connected to the first and second exchangers 12, 14 so as to develop a refrigeration cycle between the first and second exchangers in a reversible manner through a valve 18 so as to be able to perform both the function of winter heating of the rooms 2 and summer cooling. The function that most concerns the present invention is that relating to summer cooling since it is the one in which the second exchanger 14 acts as an evaporator, cools down and on it the condensate water due to the moisture present in the treated air is deposited. In this step of the cycle, the first exchanger 12 acts as a condenser to cool and condense the refrigerant gas compressed by the compressor 17 by transferring heat to the fluid circulating in the primary circuit 5, as will be further explained below.

The compressor 17 is preferably of the variable speed type, in particular of the type configured to adapt its power according to the dispersions and/or the ambient heat load and/or the availability of power and/or temperature variations on the primary circuit 5. Thanks to this configuration it is possible to adjust the power of the individual room air conditioning units 13 so as not to unbalance the system, when the devices that adjust the temperature of the primary circuit 5 (heat generator 4 or other machines/systems for cooling or heating the installation water) are insufficient to cover the demand.

Returning to the first exchanger 12, it is connected to the compressor 17 by means of pipes 19 on the gas side and is preferably connected to the manifolds 8,9 by means of the inlet pipelines 10 and the outlet pipelines 11 , both of which are preferably terminated with connectors that allow it to be easily connected directly to the manifolds 8,9 in place of, for example, the pre-existing radiators, in the case of conversion of the system from heating through boiler and radiators to heating and cooling through heat pumps.

The collector 16, generally in the form of a tray underneath the coil of the second exchanger 14, in turn conveys the collected water through a special suction duct to a pump 20 whose delivery is connected through a condensate discharge pipe 21 to the outlet pipeline 11 coming out of the first exchanger 12. The pump 20 is preferably a peristaltic, centrifugal or vibratory pump with sufficient head to transfer the condensate water to the primary circuit 5.

The accumulation of condensate water in the primary circuit 5 can then be disposed of via an outlet 22, for example controlled by a pressure regulator 23.

In this way the condensate water is efficiently collected at each heat pump unit 13 by means of a collector, for example a traditional drip tray, and is discharged directly through the primary circuit 5 without requiring auxiliary discharge circuits.

It will be noted that several heat pump units may be connected in parallel on manifolds 8,9 or may be connected in series according to the most appropriate thermotechnical selection criteria. It is also envisaged that the condensate water discharge device may include, instead of or in addition to the pump 20, an ejector preferably of the constriction type, i.e. having a localized reduction of its passage section aimed at accelerating the fluid passing through it, for example a Venturi effect ejector or a Coanda effect ejector placed along the water side and in the constriction or narrowing of which the condensate discharge pipe 21 is coupled. Preferably the condensate discharge pump is coupled along the condensate discharge pipe 21. In such a case, it is preferred that a one-way valve 24 (non-return) open in the direction of flow from the collector to the water side of the first exchanger is inserted along said condensate discharge pipe. If necessary, a tank 25 stores the condensate water to supply it to pump 20 by means of level controls 26, 27 to activate the pump 20 and produce an alarm in the event of excess condensate level in the tank 25, respectively.

Operationally, the invention provides a method for discharging condensate water in a heat pump unit including a first exchanger configured to operate as a water/gas condenser and a second exchanger configured to operate as a gas/air evaporator, wherein the condensate water generated by the heat pump unit is discharged by injecting it into the water side of the first exchanger.

The method is particularly advantageous when applied in water loop installations with a primary circuit to which the water side of each heat pump unit is connected and in which the condensate water is removed from each unit through the primary circuit.

The same type of installation is also suitable for the production of domestic hot water, as shown in Figure 4. For this purpose, the apparatus used consists of a saturated vapour compression refrigeration circuit according to a layout similar to that in Figure 5 (in which, however, both exchangers are of the refrigerant gas/water type), which absorbs heat from the primary water circuit (or loop) to bring it, by raising its temperature level, to a domestic water storage tank by means of a second heat exchanger.

This principle therefore also makes it possible to heat domestic water from the primary loop.

In summer, the combined operation of the heat pump units for cooling rooms and the domestic water heating units leads to an important energy advantage. The heat discharged into the primary loop by the heat pump units is largely recovered (and raised in temperature level) by the domestic hot water heating units.