FR3041420A1 - HOT WATER PRODUCTION DEVICE USING WASTEWATER HEAT RECOVERY, AN INSTALLATION AND A PROCESS FOR THE PRODUCTION THEREOF - Google Patents

Abstract

The invention relates to a device (100) for producing domestic hot water by wastewater heat recovery comprising a wastewater discharge circuit (1), a domestic hot water heating circuit in hot water. a first heat exchanger (2) disposed on the wastewater circuit configured to transfer heat from the wastewater to cold sanitary water resulting in preheated cold water, a heat pump (3) comprising an evaporator (4) and a condenser (5), configured to heat the cold water preheated to domestic hot water, characterized in that the evaporator (4) is arranged on the wastewater circuit downstream and in series of the first exchanger, and that the condenser (5) is arranged on the downstream and series heating circuit of the first exchanger (2) so as to heat the preheated water from the first heat exchanger, and that the device (100) does not does not include sani hot water storage not waste water. The field of the invention relates to the optimization of the production of hot water and is part of sustainable development tending to reduce the use of energy. The invention will find particular application for the recovery of heat energy from wastewater in individual dwellings for showers or other hot water consumption point or in public facilities for various hot water consumption points. shower types ...

Description

TECHNICAL AREA

The present invention relates to a device for producing domestic hot water by heat recovery of wastewater, an installation and an associated production method.

The field of the invention relates to the optimization of hot water production and is part of sustainable development tending to reduce the use of energy. The invention will find particular application for the recovery of heat energy from wastewater in individual dwellings for showers or other hot water consumption point or in public facilities for various hot water consumption points. shower types ....

STATE OF THE ART

The heat of wastewater is an energy available in large quantities in urban areas and therefore close to needs. The recovery of their thermal energy, also called "cloacothermy", is based on the same technical principles as those of ground-source geothermal energy, with the difference that the calories come from our own discharges of water, evacuated through a network sanitation.

In high-performance buildings, especially in passive houses, hot water needs are such that the energy required for its production can far exceed that of heating. The optimization of the production of hot water is therefore essential as well as that of heating.

It is about recovering heat from wastewater, also known as greywater. During their evacuation, the wastewater has an average temperature of between 10 ° C and 20 ° C, up to 40 ° C directly at the outlet of certain evacuations, for example shower. This poorly known caloric incontinence is the source of the 500 to 600 liters of wastewater consumed daily by an average family and then evacuated through the pipes.

Several solutions for recovering thermal energy from wastewater are known from the state of the art.

Document CN2879027U, a wastewater thermal energy recovery device including the passage of wastewater in a water collector and then in a cold-water preheating exchanger, is known, the preheated water then circulates towards a pump heat using a heat transfer fluid. This type of device is used to generate hot water that can be used at multiple points of consumption from different sources of wastewater. The different wastewater is stored in the wastewater collector. Wastewater is used when the production of hot water requires the recovery of extra calories. The disadvantage of this type of installation is to have a limited yield. Indeed, little thermal energy is recovered from the wastewater by the different exchangers that require a parallel power supply and significant losses noted.

There is a need to improve wastewater heat recovery devices for domestic hot water production.

SUMMARY OF THE INVENTION

The present invention proposes for this purpose a device for producing domestic hot water by heat recovery of wastewater comprising a wastewater discharge circuit, a cold water heating circuit sanitary hot water, a first heat exchanger disposed on the wastewater circuit configured to transfer heat from the wastewater to domestic cold water, resulting in preheated cold water, a heat pump comprising an evaporator and a condenser configured to heat the water cold preheated in domestic hot water. Characteristically, the evaporator is arranged on the downstream and series wastewater circuit of the first exchanger and the condenser is disposed on the cold water heating circuit downstream and in series of the first exchanger. The device does not include hot water storage or wastewater. Advantageously, the device comprises a priming circuit for initiating the operation of the heat pump. Advantageously, the priming circuit is in operation before the establishment of a stabilized flow of the wastewater stream and / or before the temperature of the domestic hot water produced has reached a set temperature of domestic hot water . This priming circuit makes it possible to shorten the temperature rise time of the water when the tap is opened, for a very modest overconsumption of water.

By this arrangement of the invention, the present device allows optimal recovery of wastewater heat with limited heat losses. Firstly, the series assembly of a first heat exchanger and the condenser of the heat pump makes it possible to optimize the heating by transferring energy from the wastewater to the sanitary cold water and then by increasing the temperature of the heat pump. water preheated by the heat pump. In addition, this preheating makes it possible with limited heat pump heat output to have optimized heating. In addition, the lack of storage of either wastewater or domestic hot water avoids the loss of heat from the water during storage.

The production of hot water is advantageously synchronized with its use. In the same way the production of hot water is synchronized with the evacuation of the waste water. The absence of storage also makes it possible to arrange the device as close as possible to the point of discharge of the wastewater and the point of consumption of hot water. The device is arranged in a decentralized manner that is to say one per point of consumption and not centralized for several points of consumption or several parts of the house.

This invention makes it possible to produce domestic hot water in a direct and decentralized manner with exceptional energy performance. The device of the invention can achieve a coefficient of performance exceeding 7.5; that is an energy saving of 86.7% compared to an electric water heater, ideal moreover without thermal losses.

This performance is achieved through an optimal architecture of the device to both minimize the amount of energy required and the temperature levels at which it is exchanged. This characteristic architecture allows a heating advantageously fully thermodynamic in a range of operation perfectly suitable for heat pumps as widely developed in the building, both in terms of power level and temperature level. The absence of stock makes it possible to limit thermal losses to a minimum and advantageously the absence of additional heating makes it possible to obtain optimal energy performance without increasing the subscription to the energy supplier.

In another aspect, the invention relates to an installation comprising the device as described above and a single point of consumption and preferably a single point of wastewater production.

In another aspect, the invention relates to a method for producing domestic hot water by heat recovery of wastewater using the device as described above comprising two successive stages of heating the cold water.

BRIEF DESCRIPTION OF THE FIGURES

The objects, objects, as well as the features and advantages of the invention will emerge more clearly from the detailed description of an embodiment of the latter which is illustrated by the following accompanying figures in which:

Figure 1: Diagram of an installation according to the invention, the device is not detailed.

Figure 2: Diagram of an installation according to the invention with the detailed device according to a first embodiment.

Figure 3: Partial diagram of an installation according to a second embodiment with lifting of wastewater.

FIG. 4: Diagram of an installation according to the invention with the detailed device according to the second embodiment of FIG.

Figure 5: Graph illustrating the temperatures of the different streams (domestic hot water, sanitary cold water and waste water) in the heating circuit of cold water in domestic hot water.

Figure 6: Graph showing the rates of hot water consumption and wastewater production.

Figure 7: Graph illustrating the law regulating the boot rate in the boot circuit.

Figure 8: Graph illustrating the correction of the power factor of the heat pump as a function of the temperature of the wastewater at the outlet of the device

Figures 9 and 10 illustrate the simulation results of an installation according to the invention in the case of a flow rate of hot water adjustable by the user with a heat pump compressor with adjustable power or variable speed.

FIG. 11: graph illustrating the flow rate of the priming circuit as a function of the difference between a set temperature of hot water and the actual temperature of the hot water.

Figures 12 and 13 illustrate the simulation results of an installation according to the invention in the case of a flow of hot water adjustable by the device with a heat pump compressor with or without power adjustment.

Figure 14: Partial diagram of an installation where the heat exchangers are integrated into a siphon.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

Before beginning a detailed review of embodiments of the invention, are set forth below optional features that may optionally be used in combination or alternatively.

It is recalled first of all that the invention relates to a device for producing domestic hot water by wastewater heat recovery including a wastewater evacuation circuit, a cold water heating circuit in hot water a first heat exchanger arranged on the wastewater circuit configured to ensure the transfer of heat from the wastewater to cold sanitary water resulting in preheated cold water, a heat pump comprising an evaporator and a condenser , configured to heat the cold water preheated to domestic hot water, characterized in that the evaporator is arranged on the wastewater circuit downstream and in series of the first heat exchanger, and that the condenser is arranged on the heating circuit downstream and in series of the first exchanger so as to heat the preheated water from the first exchanger, and that the device does not include storage of ea u sanitary hot water or waste water.

Advantageously, the device comprises a priming circuit configured to supply sanitary cold water to the evaporator of the heat pump.

Advantageously, the priming circuit is configured to temporarily supply sanitary cold water to the evaporator of the heat pump.

Advantageously, the priming circuit is configured to supply sanitary cold water to the evaporator of the heat pump before the establishment of a stabilized flow of the wastewater stream. Preferably, the device comprises a wastewater flow sensor in the wastewater circuit intended to control the establishment of a stabilized flow of the wastewater stream and thus the operation of the priming circuit.

Advantageously, the priming circuit is configured to supply sanitary cold water to the evaporator of the heat pump before the temperature of the domestic hot water produced has reached a set temperature of domestic hot water. Preferably, the device comprises a domestic hot water temperature sensor produced for controlling the adequacy between the temperature of domestic hot water produced and a target domestic hot water temperature and thus the operation of the priming circuit.

Advantageously, the initiation circuit comprises means for regulating the flow rate.

According to one possibility, the flow regulation means comprise at least one of a connection on a sanitary cold water supply pipe, a shut-off valve, a flow sensor, a flow regulator and advantageously a connection. on the wastewater circuit arranged upstream of the evaporator.

Advantageously, the device is intended to supply a single point of consumption of domestic hot water

Advantageously, the device is configured to produce domestic hot water synchronously with the use of domestic hot water.

Advantageously, the device comprises a domestic hot water consumption sensor configured to activate the production of domestic hot water.

Advantageously, the use sensor comprises at least one of a contactor on a point of consumption of hot water, a sensor on a point of consumption of hot water, a pressure switch arranged on the cold water heating circuit. Sanitary downstream of the heat pump, that is to say at the level of hot water.

Advantageously, the device comprises a temperature sensor on the heating circuit downstream of the heat pump so as to determine the outlet temperature of the domestic hot water produced.

Advantageously, the device comprises a temperature sensor on the wastewater circuit downstream of the heat pump so as to determine the outlet temperature of the wastewater.

Advantageously, the device comprises a flow control sensor arranged on the heating circuit downstream of the heat pump.

Advantageously, the first exchanger is configured to ensure a countercurrent flow of wastewater and sanitary cold water at said first exchanger.

Advantageously, the device comprises a receiver having a siphon function configured to receive the wastewater and in which the first exchanger and the evaporator dip.

Advantageously, the device does not include an auxiliary heating device.

Advantageously, the heat pump comprises a variable speed compressor or fixed; advantageously the compressor is with or without power adjustment.

In another aspect, the invention relates to an installation for producing sanitary hot water by waste heat recovery comprising the device as described above and a single point of consumption of domestic hot water produced.

Advantageously, the installation comprises a single point of wastewater production.

Advantageously, the installation comprises a sewage pump upstream of the device.

Advantageously, the installation is configured so that the production of domestic hot water is synchronized with the use of domestic hot water.

Advantageously, the installation is configured so that the production of domestic hot water is simultaneous with the production of wastewater.

In another aspect, the invention relates to a method for producing domestic hot water by heat recovery of wastewater using the device as described above comprising two successive stages of heating the cold water.

Advantageously, there is no storage of wastewater or hot water.

Advantageously, the method comprises the following steps: a) preheating the domestic cold water by the first exchanger and b) heating the preheated water obtained in step a) by a heat pump.

Advantageously, the method comprises a step of priming the heat pump by activating a priming circuit configured to supply sanitary cold water to the evaporator of the heat pump before the establishment of a stabilized flow rate. wastewater in the sewage system.

Advantageously, the method comprises a step of priming the heat pump by activating a priming circuit configured to supply sanitary cold water to the evaporator of the heat pump before the temperature of the domestic hot water produced has reached a DHW setpoint temperature.

The present invention is a device for recovering heat energy from wastewater to produce hot water. The device according to the invention integrates into an installation, which is also the subject of the invention. The installation is shown diagrammatically in FIG. 1. The installation comprises a domestic hot water usage point 13. Advantageously, the installation comprises a single point of use, for example here a shower is represented. The installation comprises a wastewater production point 15, advantageously, the installation comprises a single point of wastewater production, here represented by the evacuation of the shower water.

The production of hot water is said to be "decentralized" since production is associated with a single point of consumption 13.

The point of consumption 13 of the installation according to the invention is without accumulation, that is to say that the installation is intended for a point of consumption 13 not accumulating hot water type bath or sink with plug of closing. The installation further comprises the device 100 according to the invention which is not detailed in FIG. 1. The device 100 comprises two water flow inlets, respectively of wastewater 19 and of sanitary cold water 21 and two outlets of flow of water, respectively wastewater 20 and domestic hot water 23. The device comprises a power supply 25.

Advantageously, this device 100 is installed as close as possible to the hot water consumption point 13 and the wastewater generation point 15. The space requirement is rather limited, which means that the device can be installed directly in the room of the room. point of consumption of hot water 13 and wastewater production 15. As a non-limiting example, the volume of the device is of the order of 20cm by 30cm by 50cm for a volume of thirty liters. In addition, the device operates advantageously with a very small difference in altitude between the inlet and the outlet of the wastewater, according to an embodiment advantageously incorporating a lifting pump 29, this difference can be zero.

The sound level of the device in operation is low, preferably less than 40 dB.

The device according to the invention comprises a wastewater evacuation circuit 1 and a cold water heating circuit in domestic hot water. The terms circuits include the pipes / tubes / fittings allowing the circulation of the different streams of water.

The device comprises a first heat exchanger 2, also called recuperative heat exchanger, placed on the wastewater circuit 1 downstream of the wastewater production point 15. The first exchanger 2 comprises a sanitary cold water inlet. Advantageously, the flow of wastewater and sanitary cold water is countercurrent in the first exchanger 2 so as to improve heat transfer. This first exchanger 2 is intended to preheat the sanitary cold water by transferring the heat energy of the wastewater. The preheated sanitary cold water flows from the first heat exchanger 2 and flows into the heating circuit of the sanitary cold water.

The device advantageously comprises a heat pump 3 which can also be called a refrigeration loop. The heat pump 3 comprises an evaporator 4 and a condenser 5. Advantageously, the heat pump 3 comprises between the evaporator 4 and the condenser 5 a compressor 26 and an expansion member 27. The compressor 26 can be at a speed fixed or variable speed.

This means that under given conditions, the compressor has or not a setting means for modulating the thermal power. We speak of speed or displacement, for example in speed or fixed displacement, the thermal power depends on the operating conditions, without adjustment possible. This means that the compressor is respectively without or with power adjustment. The evaporator 4 and the condenser 5 are heat exchangers. In the heat pump 3 circulates a refrigerant. In the exchangers, the refrigerant exchanges thermal energy with another fluid; in the evaporator 4, the refrigerant exchanges heat energy with the wastewater to heat up, in the condenser 5, the refrigerant exchanges the heat energy with the cold water preheated to increase its temperature.

The capacitor 5 is advantageously arranged on the circuit for heating cold water with domestic hot water downstream of the first heat exchanger 2. The capacitor 5 is arranged in series with the first heat exchanger 2. This arrangement makes it possible to optimize the device by sub-dimensioning the 3. The capacitor 5 makes it possible to significantly increase the temperature of the preheated water coming from the first heat exchanger 2. The evaporator 4 is advantageously arranged on the wastewater discharge circuit 1 downstream of the first heat exchanger. 2. In this way, the evaporator 4 recovers thermal energy from the wastewater for transmission to the preheated water via the refrigerant.

The heat pump 3 comprises, according to an optional embodiment, an intermediate heat exchanger disposed between the evaporator 4 and the condenser 5 internal to the refrigerant loop of the heat pump 3 so as to optimize the recovery of sensible thermal energy from the heat exchanger. waste.

The heat pump 3 may optionally comprise an expansion energy recovery system and / or a refrigerant reserve and / or a filter and / or a set of solenoid valves and / or an economizer exchanger. The set of solenoid valves makes it possible in particular to stop the heat pump, to seal the different parts of the refrigerant circuit between them to prevent the migration of fluid. At restart, this allows the heat pump to be more reactive.

According to variants of the invention, other means for raising the temperature can be provided in the device, for example a magnetocaloric heat pump or by sorption (adsorption or absorption), or thermoelectric heat pump.

Characteristically, the device according to the invention does not include storage of wastewater or hot water storage. The absence of liquid storage means that there is no point of stagnation in the device, which has several advantages. Inertia is reduced and start-up time is faster. The production temperature is lower since it is not necessary to predict the thermal losses due to storage and transport. The constraints to avoid the proliferation of bacteria do not apply, which makes it possible to avoid expensive high temperature cycles.

The device according to the invention is configured to produce hot water synchronously to the consumption of hot water. The production of hot water is called "direct", it is temporally synchronized with the use, it intervenes at the same time, they are simultaneous. Synchronized or simultaneous means that the production and use are performed simultaneously, however according to the invention the production and use may have an offset of less than one minute preferably of the order of 30 to 20 seconds without delivering in question the principle of the invention.

The direct production of domestic hot water allows the device to operate at the lowest hot water temperature possible, especially in the context of the invention where the production device is located close to the point of use.

The device according to the invention does not include a supplementary heating element. Indeed, the production of hot water being direct and the device according to the invention being optimized to have a good general arrangement that allows to make the most of the heat recovery on greywater, it is not necessary to provide a complementary water heating element type water heater for example.

The instantaneous power consumption of the device is 3000W maximum.

The device according to the invention advantageously comprises a priming circuit 6. The priming circuit 6 is configured to introduce sanitary cold water into the wastewater circuit 1 upstream of the evaporator 4 and advantageously downstream of the first exchanger 2. Thus, the evaporator 4 and therefore the heat pump 3 can directly operate from the hot water use signal identified. The temperature rise time of the water is shortened and the consumption of water very modest. This provision makes it possible not to use an additional electric heating or other.

Indeed, as illustrated in FIG. 6, during the consumption of hot water, that is to say the opening of the hot water tap, the flow of wastewater does not appear instantly in the device. A pure delay with a damped effect is found. The priming circuit makes it possible to reduce this delay at the level of the evaporator 4. Advantageously, the priming circuit 6 is actuated as soon as the hot water tap is opened at the point of consumption 13 and according to a possibility until a preferentially stabilized and preferably predetermined waste water flow circulates in the wastewater evacuation circuit 1. Advantageously, the device comprises a flow sensor for the flow of wastewater into the wastewater discharge circuit 1 The sensor determines the flow rate of the wastewater stream in the wastewater evacuation circuit 1 and advantageously control means make it possible to determine its adequacy with a flow of wastewater of setpoint that is to say predetermined . According to a second alternative or cumulative possibility, the priming circuit 6 is actuated until the difference between the temperature of the domestic hot water at the outlet of the device and the set temperature for the domestic hot water is zero As illustrated in FIG. 11. As illustrated in FIGS. 2 and 4, the device comprises a temperature sensor 28 intended to determine the temperature of the domestic hot water leaving the device. Advantageously, control means make it possible to determine the suitability with a set, ie predetermined, sanitary hot water temperature.

The priming circuit 6 comprises a connection 8 on the sanitary cold water inlet duct 7 in the device. The ignition circuit 6 advantageously comprises a control means for activating or deactivating the ignition circuit 6. The control means is at least one shut-off valve 9 arranged on the ignition circuit 6. The circuit of FIG. priming advantageously comprises a control means or means for regulating the flow rate of the cold water flow by way of example at least one sensor 11 and 10 flow regulator.

The priming circuit 6 is connected fluidically by a connection 12 to the wastewater circuit 1 upstream of the evaporator 4. Thus, the priming circuit 6 supplies sanitary cold water to the evaporator 4 before it is powered by wastewater.

Advantageously, the priming circuit 6 allows the start of the device when a consumption of hot water is required to use the cold water as cold source. Preferably, the means for regulating the flow rate 10 of the sanitary cold water in the priming circuit 6 makes it possible to progressively increase the power of the device and to manage the cold source transition of the evaporator 4 between the cold water Sanitary priming and sewage in steady state.

Advantageously, the device according to the invention comprises temperature sensors for controlling the temperature of the different streams of water circulating in the device. The device advantageously comprises a temperature sensor 28 for the domestic hot water stream 23 at the outlet of the device, downstream of the heat pump 3, so as to identify the outlet temperature and possibly adjust it.

According to an advantageous possibility, the device comprises a temperature sensor 17 at the inlet of the device for the stream of sanitary cold water inlet 21, upstream of the first exchanger 2 and the priming circuit 6. This temperature sensor 17 allows to limit the risk of freezing in the device in case of sanitary water of very low temperature.

Preferably, the device comprises a temperature sensor 16 disposed on the wastewater stream 20 at the outlet of the device, preferably downstream of the evaporator 4.

According to the invention, the production of domestic hot water is simultaneous with the consumption of domestic hot water. The device advantageously comprises a domestic hot water consumption sensor so as to detect a withdrawal of hot water and trigger the actuation of its production. By way of example illustrated, the device comprises a pressure switch 14 located on the circuit for heating the cold water with domestic hot water downstream of the heat pump 3, preferably on the hot water outlet stream 23. D Other sensors located at the point of consumption 13 can be used as a sensor directly at the point of consumption, for example the hot water tap, a contactor on the tap or a position sensor on the tap.

According to a preferred embodiment, particularly in the case of a single-speed heat pump compressor 3, the device comprises a thermostat located on the domestic hot water stream 23, downstream of the heat pump 3, More precisely, the condenser 5. This component provides flow control as a function of temperature. It may be replaced by a flow regulator 18 connected by the regulation to the temperature measured downstream of the condenser 5 on the flow 23 by the temperature sensor 28.

The device advantageously comprises a controller or regulator of the device not shown in the figures. This regulating member is intended to control the device according to the invention and in particular the set temperature of the hot water flow at the outlet 23 of the device. This regulator is preferably accessible to the user for viewing and / or modifying the operating parameters of the device. By way of example, by copying the position of the mixer, that is to say a sensor of the mixer position to transmit the information to the device, or by a control panel independent of the valve in place.

According to a variant illustrated in Figure 3, the installation comprises a sewage lifting element. The lifting element can also be integrated in the device as such. The lifting of wastewater makes it possible to use better exchangers whose loss of load would be unacceptable in the context of a gravity system. On the other hand, the sewage lifting allows the device to adapt to almost any situation since the modification of the existing wastewater evacuation network 33 is reduced to a minimum, the flow in the evacuation network 33 remains almost identical to the initial flow without the device according to the invention. Indeed, the lift makes it possible to deport the device according to the invention and to free it from gravity constraints, in particular as regards the minimum difference in height required. This arrangement leaves the flow in the evacuation network 33 free in case of maintenance of the device and makes possible the combination with another system for producing domestic hot water. By this is meant that the present invention can be fully installed on the cold water pipe for installing or keeping in parallel a hot water pipe from a balloon or a boiler for example

According to this variant, the device comprises a sewage lifting pump 29. The lifting pump 29 is disposed on the incoming flow of the waste water 19 in the device, more precisely in the first exchanger 2.

In FIGS. 3 and 4, there is illustrated a siphon 30 at the base of the wastewater production point 15. A connection 31 advantageously disposed in the siphon 30 makes it possible to separate the wastewater produced in two streams: a flow entering 19 into the device 100 of the invention and a discharge stream of waste water 32 in an evacuation network 33. Preferably, the device comprises a water presence detection member in the siphon 30, for example by reading the level. This detection member is configured to activate or not the lift pump 29 located between the connection 31 and the first exchanger 2 of the device.

Advantageously, the regulation being made so that the flow of wastewater passes completely into the device 100 during a hot water demand.

Preferably, as illustrated in FIGS. 3 and 4, the flow of wastewater downstream of the device is connected downstream of the siphon 30 to the wastewater evacuation network 33, advantageously located on a downwardly sloping portion of the network 33 to avoid parasitic recirculation to the connection 31 making the water intake for the device. The outflow of the wastewater 20 from the device returns to the discharge network 33 via the connection 34. Optionally, an anti-return valve is placed on the initial wastewater discharge network 33 between the two connections 31 and 34. .

Advantageously, the device is equipped with wastewater treatment means of the incoming stream 19. The processing means comprise, for example at least filter and / or grinder. The treatment of the incoming wastewater stream 19 makes it possible to use exchangers having efficiencies greater than those of the exchangers generally used directly on the wastewater. Indeed, the fouling being less after treatment, the characteristic dimensions of the exchangers can be reduced without risk of clogging. The overall performance is improved by the use of such exchangers.

According to a variant of the installation illustrated in FIG. 14, the device is at least partially integrated in a siphon 30 in. This arrangement reduces the height required under the collection of wastewater. As illustrated, under the wastewater collection point 15, the device comprises a wastewater receiver 35 in which the first exchanger 2 and preferably the evaporator 4 of the heat pump 3 are immersed. Sanitary cold water 21 entering the device 100 directly enters the receiver 35 receiving the wastewater, as well as the evaporator 4 for which the refrigerant circulates in the receiver 35. The receiver 35 does not store the wastewater for their storage. The receiver 35 only allows to immerse the exchangers and the volume can be reduced to a minimum.

In the case of a device in which the compressor 26 is at single speed, and in the event of a lack of flow of sanitary cold water and / or wastewater in the installation with respect to the minimum flow rate sufficient for the operation of the device , the hot water produced exceeds the desired target. It is then a defect outside the device that must lead to the security of it. The device advantageously comprises a bypass of sanitary cold water to the outlet stream of domestic hot water 23 produced. On this derivation, advantageously a flow control valve assures the dosing of the amount of cold water sufficient to cool the hot water produced by the device in order to lower it to the temperature setpoint chosen, unless there is has a lack of cold water flow as mentioned above.

According to the invention, the method for producing domestic hot water by heat recovery of the wastewater comprises at least two steps of heating the water. The first step is a sensible heat recovery by circulating the sanitary cold water, advantageously against the current, wastewater in a first exchanger 2 which can be of low efficiency, typically 60%. Another subsequent step is the heating of cold water at intermediate temperature, also called water preheated in domestic hot water by the condenser 5 of a heat pump 3 whose evaporator 4 is located on the wastewater circuit 1 .

These two main phases of water heating are identifiable in FIG. 5. In this figure, the increase in the temperature of the sanitary cold water entering the device can be seen to increase in two stages represented by two inclinations of the curve corresponding to the passages of the water to be heated first in the first exchanger 2 and then in the condenser 5. In parallel, the graph illustrates the temperature of the wastewater between the inlet and the outlet in the device. At the condenser 5 and the evaporator 4, the temperature of the refrigerant circulating in the heat pump 3 is shown in dotted lines.

Chronological description of an operating cycle of an installation according to the invention: The user opens the hot water tap. This hot water withdrawal information is transmitted to the device according to the invention.

In the priming circuit 6, the valve 9 is activated and the flow regulator 10 adjusts the flow rate of the domestic cold water circulating in the ignition circuit 6 as a function of the difference between the setpoint and the actual value of the the hot water temperature, advantageously measured at the outlet of the device by the temperature sensor 28.

The compressor 26 is turned on. If the compressor 26 is at variable power, the starting power setpoint depends on the cold water temperature at the inlet of the device, advantageously measured by the temperature sensor 17.

Wastewater begins to flow through the sewage system 1, usually the arrival of sewage occurs less than a minute after opening the hot water faucet.

In the case of a compressor 26 with a variable speed (or displacement), the speed reference changes according to the difference between the set point and the measurement of the hot water temperature, as well as according to the safety against freezing in the wastewater circuit 1 downstream of the evaporator 4.

The valve 9 is closed, the device then operates in steady state:

In the case of a fixed power compressor 26, the flow rate is set by the device.

In the case of a compressor 26 with variable power, the flow of domestic hot water can be set by the user and the compressor power setpoint depends on the latter. The user closes the hot water faucet. End of hot water withdrawal. This information is transmitted to the device.

The compressor 26 is cut and the valve 9 of the ignition circuit remains closed

The device according to the invention has at least two modes of operation as a function of the compressor 26 of the heat pump 3 selected: a variable flow operation set by the user with a compressor 26 with power control, or a flow operation fixed fixed by the device: with a compressor 26 without or with power adjustment.

By variable flow set by the user is meant that the flow of domestic hot water produced by the device is set by the user when he uses the hot water at the consumption point 13 and is meant fixed flow operation set by the device that the flow of domestic hot water produced by the device is set by device and that the user can not change the flow of hot water at the point of consumption 13.

When the compressor 26 is a variable speed compressor, the priming circuit 6 is not necessary because the compressor 26 can adapt its flow rate as a function of the flow rate of the wastewater entering the heat pump 3. Its activation accelerates still the rise in temperature of the hot water from the withdrawal of hot water at the point of consumption 13. The effectiveness of the recovery device according to the invention is in particular functions of external conditions. In particular, the temperature of the cold water that itself depends on several factors, including the location and the time of year. The device according to the invention is configured to operate whatever the temperature of cold sanitary water, preferably above 6 ° C; the minimum temperatures are the most critical, the device is advantageously sized for cold water temperatures between 6 and 10 ° C. Domestic hot water at the point of consumption 13 is generally between 37 and 39 ° C, especially for shower use.

On the other hand, the temperature of the wastewater depends on several factors related in particular to the geometry and the configuration of the water point, as well as to the characteristics of the place. The decrease in hot water temperature results from the passage of hot water in a colder environment before reaching the wastewater network. This passage can be considered as a heat exchanger for the purpose of dimensioning the device according to the invention.

The regulation laws for the device according to the invention are described below, the flow of hot water produced is regulated by the user in dynamic mode (via the opening of the valve for example). We analyze the most critical phase: startup. The parameters being variable during this phase, the computation is carried out by dynamic simulation, that is to say that it describes the evolution of the parameters as a function of time.

The regulated quantities are 2 in number: a) Compressor 26 power factor (or proportional speed)

This is regulated according to a set point and a constraint:

Temperature setpoint on produced hot water

Frost limit constraint on the wastewater at the outlet of the device.

The regulation of the power factor is proportional, integral and derivative action, it is limited to the interval [0, 1],

The temperature limit of the wastewater is given by a direct acting law coupled to a derivative action. The direct acting law takes the form of the first quarter of a sinusoid whose abscissae are the limiting temperature and the tilting temperature. Above a so-called temperature of rocking temperature, no corrective action is made to the power factor of the compressor 26 as illustrated in FIG. 8. FIG. 8 illustrates the correction of the power factor of the compressor 26 as a function of the temperature. wastewater at the outlet of the device. The minimum temperature is 0 ° C and the rocking temperature is here 3 ° C. The derivative action consists in observing the variations in the wastewater temperature at the outlet of the device, preferably by the temperature sensor 16, in order to anticipate the necessary correction of the power factor. The response of this derived function is processed by an integral delay function to stabilize the device.

A dynamic thermal simulation study makes it possible to observe the behavior of the complete device with its own regulation during a "cold" start. For this, the performance of a compressor 26 commercially available have been reproduced. Similarly, the modeled exchangers have comparable performances to commercially available products, for example with an efficiency of 60% for the first exchanger 2.

The results are illustrated in Figures 9 and 10 demonstrate that the proposed implementation allows for the production of domestic hot water respecting the constraints of the user and the environmental elements influencing the device. The response of the real device can be optimized with refined regulation and with potentially more powerful components than those modeled in this case. b) Priming circuit flow

This quantity is regulated as a function of the difference between the hot water set point temperature and the measurement of this temperature by the temperature sensor 28 on the hot water outlet stream 23 of the device. A maximum flow rate constant of the priming circuit is set at manufacture.

As shown in Figure 7, when this difference is greater than 20 K equivalents at 20 ° C, the maximum firing rate is provided. Between 20K and 1K, it is gradually reduced to 0. The slope of this flow law must be continuous, to promote the stability of the device regulation.

Figures 9 and 10 illustrate the different temperatures and flow rates in the device according to the operating mode of the compressor with power adjustment.

It is found that the hot water temperature at the outlet of the device stabilizes after 28 s. this delay corresponds to the introduction of the priming flow and then the flow of wastewater and finally the gradual reduction of the priming flow rate illustrated in FIG. 10. As soon as the hot water is drawn off, the priming circuit 6 becomes place (Fig. 10) and the temperature of hot water produced increases very rapidly. When the wastewater flow rate increases, the priming flow rate decreases and the temperature of the preheated water after the first exchanger 2 increases gradually as well as the temperature of the hot water produced.

The regulation laws for the device according to the invention, the flow rate of which is fixed by the device in dynamic mode, are described below.

The regulated magnitudes are two in number: a) The flow of hot water produced The advantage of this case lies in the fact that it is possible to use a compressor 26 with a single speed. This type of compressor 26 has very good performance and may have a commercial advantage. By extension, a variable speed compressor may also be suitable.

In steady state, the device aims to provide hot water at the temperature requested by the user. For this, the regulation acts on the flow of hot water produced: an increase in this flow rate reduces the temperature of hot water because the thermal power supplied to the device by the heat pump 3 is almost constant. Conversely, a decrease in the flow of hot water increases its temperature. In this way, the flow of water is no longer defined by the user but by the device.

The transient start phase can be realized in two different ways. In both cases, the delay of occurrence of the wastewater flow rate illustrated in FIG. 6 necessitates the use of priming circuit 6 to accelerate the start-up process. - The nominal flow is generated from the start of the withdrawal, the temperature of the water at the point of consumption 13 is first cold and then gradually warms up.

The necessary regulation and adjustment are described below: • Priming flow: The priming is done by the flow of cold water directed to the first heat exchanger 2. For each given cold water temperature, there is a flow rate sufficient priming to avoid the risk of frost in the first exchanger 2. In the case of the system presented in the example below and for cold water at 9 ° C, an initial priming flow rate of 101 / min is sufficient to avoid the risk of frost. Apart from the parameter of the maximum value, the flow control law is the same as in the case of the device where the flow rate is set by the user and using a variable speed compressor 26. • Domestic hot water flow and temperature of hot water produced:

The performance table presented below shows that there is a single hot water flow for a given device, a given cold water temperature and a given hot water temperature. The values of such a table are calculated from the performance of the device components, and can also be measured on a real device.

On a real device, a correction is advantageously applied at this rate to increase the robustness of the device in the face of possible hazards: lack of flow, variation in performance of the components. Mainly, this correction makes it possible to avoid overheating by increasing the setpoint flow if the set temperature is exceeded. The appearance of this correction function is illustrated in FIG. 11, where the slope of the first part of the curve depends in particular on the power of the compressor installed, its value is typically -1.5 for a flow rate expressed in L / min. This correction is added to the flow initially fixed by calculation.

FIGS. 12 and 13 illustrate the start-up operation of a device equipped with a single-speed compressor, the flow rate of which is set to nominal at start-up. This value is deliberately underestimated in this example to illustrate the operation of the flow rate correction as a function of the hot water temperature produced.

In this mode of operation, it is found that the hot water temperature at the outlet of the device stabilizes after 16s.This delay corresponds to the establishment of the priming flow and then the flow of wastewater and finally the progressive reduction of the priming flow rate illustrated in Figure 13. The delay is shorter than in the previous operating mode illustrated in Figures 9 and 10 because the flow of hot water is not maximum from the start of the racking but increases only once the set temperature is reached. As soon as the hot water is withdrawn, the seeding rate is set up, the reduction of the priming flow rate in favor of the wastewater flow is faster than in the previous operating mode. In this case, the boot rate is stronger at the beginning, resulting in a faster decrease. The rate of decrease of this flow rate is also related to the general dynamics of the device since this flow rate is inversely calibrated to the rise in temperature of the domestic hot water. - The flow is initially limited to reach very quickly the set temperature requested by the user. The flow then increases gradually to the nominal point.

As in the previous case, the regulation deals with the following parameters: a) Priming flow rate

The same remarks and principle as for the rated flow rate case apply here. b) Domestic hot water and hot water temperature flow In this case, the domestic hot water flow is the addition of the nominal flow rate with a proportional and integral correction in relation to the difference between the temperature setpoint and the measured temperature. This law must be particularly reactive.

Examples of Device Performance in steady state

Example 1: case of the single-speed compressor The energy study of the device shows that there exists, with given components, a single flow of domestic hot water for which the produced water temperature reaches a chosen setpoint, ie about ° C for direct domestic hot water. With assumptions similar to those used for the dynamic simulation of the device, the results of the energy balances show that the coefficients of performance (COP) exceed 7.5, ie a saving of 86.7% compared to a joule effect heating, without taking into account the benefit of reducing heat losses due to the decentralized nature of the facility and the lack of stock.

Performance with a single speed compressor, for 3 cold water temperatures:

Example 2: Variable speed compressor case

In this case, the energy study makes it possible to define the power factor necessary for the hot water temperature to be reached with the flow rate desired by the user. The coefficients of performance are of the same order as for the case of the fixed speed compressor.

REFERENCES 1. Sewage disposal circuit 2. First heat exchanger 3. Heat pump 4. Evaporator 5. Condenser 6. Priming circuit 7. Sanitary cold water supply duct 8. Priming circuit connection 9 Shutoff valve 10. Flow controller 11. Flow sensor 12. Priming circuit connection 13. Hot water consumption point 14. Pressure switch 15. Sewage production point 16. Temperature sensor 17. Temperature sensor 18. Flow control sensor 19. Sewage flow at the inlet of the device 20. Sewage flow at the outlet of the device 21. Flow of incoming cold water into the device 22. Flow of water Sanitary cold water in the priming circuit 23. Domestic hot water flow at the outlet of the device 24. Intermediate water flow of the device 25. Electrical supply 26. Compressor 27. Expansion device 28. Temperature sensor 29. Pump of sewage lifting 30. S iphon 31. Connection to the lift pump 32. Sewage discharge stream 33. Sewage system 34. Connection 35. Receiver 100. Device

Claims (24)

1. Device (100) for producing domestic hot water by heat recovery of wastewater comprising a wastewater discharge circuit (1), a domestic hot water heating circuit in hot water, a first exchanger (2) disposed on the wastewater circuit (1) configured to ensure the transfer of heat from the wastewater to cold sanitary water resulting in preheated cold water, a heat pump (3) comprising an evaporator (4) and a condenser (5), configured to heat the cold water preheated to domestic hot water, characterized in that the evaporator (4) is arranged on the wastewater circuit downstream and in series of the first exchanger, and that the condenser (5) is arranged on the downstream and series heating circuit of the first exchanger (2) so as to heat the preheated water from the first exchanger, and that the device (100) comprises a boot circuit (6) co nfiguré for supplying sanitary cold water evaporator (4) of the heat pump (3), and that the device (100) does not include hot water storage or wastewater. 2. Device (100) according to the preceding claim wherein the ignition circuit (6) is configured to supply sanitary cold water evaporator (4) of the heat pump (3) before the establishment of a flow stabilized wastewater in the sewage system (1). 3. Device (100) according to any one of the two preceding claims wherein the priming circuit (6) is configured to supply sanitary cold water evaporator (4) of the heat pump (3) before the the temperature of the domestic hot water produced has reached a set DHW temperature. 4. Device (100) according to any one of the preceding claims wherein the priming circuit (6) comprises at least one of a connection (8) on a sanitary cold water supply duct (7). , a shut-off valve (9), a flow sensor (11), a flow regulator (10) and a connection (12) to the wastewater circuit (1) arranged upstream of the evaporator (4). ). 5. Device (100) according to any one of the preceding claims wherein the device (100) is intended to supply a single point of consumption (13) in domestic hot water. 6. Device (100) according to any one of the preceding claims wherein the device (100) is configured to produce domestic hot water synchronously with the use of domestic hot water. 7. Device (100) according to the preceding claim comprising a domestic hot water usage sensor configured to activate the production of domestic hot water. 8. Device (100) according to the preceding claim wherein the use sensor comprises at least one of a contactor on a point of hot water consumption, a sensor on a point of hot water consumption, a pressure switch (14) arranged on the heating circuit downstream of the heat pump (3). 9. Device (100) according to any one of the preceding claims comprising a temperature sensor (28) on the heating circuit downstream of the heat pump (3) so as to determine the outlet temperature of the hot water Sanitary produced. 10. Device (100) according to any one of the preceding claims comprising a temperature sensor (17) on the wastewater circuit (1) downstream of the heat pump (3) so as to determine the outlet temperature used waters. 11. Device (100) according to any one of the preceding claims comprising a flow regulator sensor (18) arranged on the heating circuit downstream of the heat pump (3). 12. Device (100) according to any one of the preceding claims wherein the first exchanger (2) is configured to ensure a countercurrent flow of waste water and sanitary cold water at said first exchanger (2). 13. Device (100) according to any one of the preceding claims comprising a receiver (35) having a siphon function configured to receive the waste water and in which plunge the first exchanger (2) and the evaporator (4). 14. Device (100) according to any one of the preceding claims not comprising a supplementary heating device. 15. Installation for producing domestic hot water by heat recovery of wastewater comprising the device (100) according to any one of the preceding claims and a single point of consumption (13) of the domestic hot water produced. 16. Installation according to the preceding claim comprising a single point of wastewater production (15). 17. Installation according to any one of claims 15 or 16 comprising a lifting pump (29) wastewater upstream of the device (100). 18. Installation according to any one of claims 15 to 17 configured for the production of domestic hot water is synchronized with the use of domestic hot water. 19. Installation according to any one of claims 15 to 18 configured for the production of domestic hot water is simultaneous with the production of waste water. 20. A method for producing domestic hot water by heat recovery of wastewater using the device (100) according to any one of claims 1 to 14 comprising two successive steps of heating the cold water. 21. Method according to the preceding claim wherein there is no storage of waste water or hot water. The method of any one of claims 20 or 21 comprising the steps of: a. Preheating the domestic cold water by the first heat exchanger (2) b. Heating the preheated water obtained in step a. by a heat pump (3). 23. A method according to any one of claims 20 to 22 comprising a step of priming the heat pump (3) by activation of a priming circuit (6) configured to supply sanitary cold water to the evaporator ( 4) of the heat pump (3) before the establishment of a stabilized wastewater flow in the wastewater drainage circuit (1). 24. A method according to any one of claims 20 to 23 comprising a step of priming the heat pump (3) by activation of a priming circuit (6) configured to supply sanitary cold water to the evaporator ( 4) of the heat pump (3) before the temperature of the domestic hot water produced has reached a set DHW temperature.