Defrosting method in a heat pump unit comprising a plurality of modules

Abstract

A defrosting method is provided for a heat pump unit (1), the heat pump unit (1) comprising a plurality of modules (2), each comprising a heating circuit (20) housing a working fluid, a compressor (21) for circulating the fluid within the heating circuit (20), a lamination valve (22), internal to the heating circuit (20), auxiliary control means (23) of an electronic type, adapted to control the modules (2); the heat pump unit (1) further comprises at least one external heat exchanger (3), adapted to exchange heat between the working fluid of all the modules (2) and an external environment, at least one internal heat exchanger (4), adapted to exchange heat between the working fluid of all said modules (2) and an internal environment, and main control means (5) of an electronic type, adapted to control the unit (1) and in connection with the auxiliary control means (23); the defrosting method further comprises the detection, by means of said main control means (5) and / or said auxiliary control means (23) of at least any one of said modules (2), needing for defrosting, the subsequent activation of a defrosting procedure of the external heat exchanger (3) for all said modules (2), wherein the ending of said defrosting procedure is controlled exclusively by the main control means (5).

Description

[0001] The present invention relates to a defrosting method in a heat pump unit comprising a plurality of independent modules that contribute to conditioning (heating or cooling) an environment or, in general, to providing conditioning to an environment (ambient air, water loop, or a plurality of fan coils), of the type specified in the preamble of the first claim.

[0002] Heat pump units suitable for conditioning environments are currently known. The term "environments" refers to fluids, such as heating water, domestic hot water, and similar, or gaseous substances, such as enclosed rooms and similar.

[0003] As is known, heat pump units are provided with circuits housing a working fluid and comprise: a compressor for circulating said fluid in said circuit, a lamination valve for evaporating and consequently cooling the fluid, a heat exchanger with an external environment for exchanging heat between said working fluid and the external environment, and a heat exchanger with the internal environment for exchanging heat between said working fluid and the previously described internal environment. Heat pump units adapted to provide both heating and cooling to a user, ambient air, or fluid further comprise valve means adapted to reverse the refrigerant cycle in the circuits. Heat pump units also include electronic-type control means.

[0004] Heat pump units comprising a plurality of independent modules are also known, each having its own refrigerant circuit and each with at least part of the aforementioned elements, such as the compressor, the lamination valve, and the control electronics, which contribute to heating a single internal environment, for example, a liquid that, in turn, heats environments. These heat pumps are commonly referred to as multi-circuit.

[0005] Such heat pump units comprising a plurality of modules can structurally and functionally share one or more heat exchangers.

[0006] These modular units are highly advantageous in terms of production costs, as identical and standardized modules can be produced and then assembled during the installation step.

[0007] The known art described above has some significant drawbacks.

[0008] In particular, heat pump units that exchange heat with the external environment to heat the working fluid can lead to the formation of frost or ice at the external heat exchanger.

[0009] This drawback is generally overcome with an operation called defrosting, which can be carried out in multiple ways.

[0010] The most common defrosting method is performed by reversing the thermal cycle of the heat pump for a period of time sufficient to melt said frost or ice. During this cycle reversal, the pressurization direction of the compressor is inverted (usually through valve means, such as four-way valves, which act by reversing the direction of the refrigerant in the circuit). The internal heat exchanger enables heat to be transferred from the internal environment to the working fluid, while the external heat exchanger enables heat to be transferred from the working fluid to the external environment. This heat causes the melting or detachment of the ice or frost. Said operation is adjusted by control means and specific sensors or preset parameters. In modular units, defrosting is more problematic because if the different modules operate independently from one another, the system may not achieve optimal efficiency, as the energy efficiency when defrosting a single unit does not always coincide with the energy efficiency for defrosting all the heat exchangers, particularly if the structure and function of the external heat exchanger are shared. Furthermore, during defrosting performed by reversing the heat pump cycle, the modules and their respective circuits engaged in defrosting do not provide a useful effect to the user to which they are connected.

[0011] Patent application CN-A-110701659, published in 2020 in the name of University Beijing Technology (China), describes a system that attempts to solve this problem by providing a single control system that commands defrosting in the units. Patent application US-A-2023288112, published in 2023 and filed by Continual Energy Inc. (US), describes a system that attempts to solve this problem by minimizing the number of units defrosting in parallel.

[0012] Patent application EP-A-3671058, published in 2023 and filed by Ademco Inc. (US), on the other hand, describes the conditions of the individual modules for which defrosting may be required.

[0013] Other similar devices are described in the following patent applications: US-A-4266599, WO-A-2015 / 198742, CN-A-107975990, and US-A-2017 / 299228. Despite attempts to solve this problem, it remains substantially unresolved, as the described solutions fail to optimize defrosting conditions.

[0014] In this situation, the technical task underlying the present invention is to devise a defrosting method in a heat pump unit comprising a plurality of modules, as well as a heat pump unit comprising a plurality of modules capable of substantially overcoming at least part of the aforementioned drawbacks.

[0015] Within this technical task, an important object of the invention is to achieve a defrosting method in a heat pump unit comprising a plurality of modules that allows for maximizing the energy efficiency of the heat pump unit.

[0016] A further object of the invention is to minimize the total defrosting operation time in a heat pump unit comprising a plurality of modules.

[0017] Another important object of the invention is to provide a defrosting method in a heat pump unit comprising a plurality of modules that is simple and effective.

[0018] An additional important object of the invention is to provide a heat pump unit comprising a plurality of modules that is simple and effective.

[0019] The technical task and the specified objects are achieved by a defrosting method in a heat pump unit comprising a plurality of modules and by a heat pump unit as claimed in the appended independent claims.

[0020] Preferred technical solutions are highlighted in the dependent claims.

[0021] The features and advantages of the invention are clarified below by a detailed description of preferred embodiments of the invention, with reference to the attached drawings, wherein: Fig. 1 shows a schematic representation of the heat pump unit according to the invention; and Fig. 2 shows a schematic representation of the defrosting procedure according to the invention.

[0022] In this document, the measurements, values, shapes, and geometric references (such as perpendicularity and parallelism), when associated with words like "about" or other similar terms such as "approximately" or "substantially", should be understood as allowing for measurement errors or inaccuracies due to production and / or manufacturing errors and, especially, minor deviations from the value, size, shape, or geometric reference with which they are associated. For example, such terms, when associated with a value, preferably indicate a deviation not exceeding 10% of the value itself.

[0023] Moreover, terms such as "first", "second", "upper", "lower", "main", and "secondary" when used do not necessarily identify an order, priority of relation, or relative position but may simply be used to more clearly distinguish different components from one another.

[0024] Unless otherwise specified, as inferred from the following discussions, terms such as "processing", "computing", "determining", "computation", or similar should be understood as referring to the action and / or processes of a computer or similar electronic computation device that manipulates and / or transforms data represented as physical quantities, such as electronic magnitudes of records of a computing system and / or memories, into other data similarly represented as physical quantities within computer systems, records, or other information storage, transmission, or display devices.

[0025] Unless otherwise indicated, the measurements and data reported in this text are to be considered as performed in International Standard Atmosphere ICAO (ISO 2533:1975).

[0026] With reference to the Figures, the heat pump unit according to the invention is generally denoted by reference number 1.

[0027] It is adapted to allow the implementation of the method described below.

[0028] The heat pump unit 1 preferably comprises a plurality of modules 2, preferably similar or identical to one another. These can be in a number ranging from two to five or even more.

[0029] The unit 1 is preferably adapted to operate between a single external environment 11, preferably consisting of the Earth's external atmosphere, thus a gaseous environment, and an internal environment 12. The internal environment, or internal load, is preferably a liquid environment, such as a heating liquid for industrial or domestic uses (e.g., a water loop). Alternatively, the internal environment 12 is an environment such as an enclosed space characterized by the presence of gas, thus air or similar, in which the various modules operate together (e.g., via fan coil units). Preferably, each module 2 comprises, in broad terms, a heating circuit 20 housing a working fluid, a compressor 21 for circulating the fluid within the heating circuit 20, and a lamination valve 22, internal to the heating circuit 20. These components are known in themselves and are substantially present in every known heat pump unit, wherein the working fluid is compressed and consequently heated, and expanded and consequently cooled by the lamination valve. The working fluid also transfers heat to the environment it must heat and absorbs heat from the environment it must cool.

[0030] Each module 2 further preferably comprises auxiliary control means 23 of an electronic type, adapted to control at least said module 2.

[0031] The heat pump unit 1 further preferably comprises at least one external heat exchanger 3, adapted to exchange heat between the working fluid of all the modules 2 and the external environment. This external heat exchanger 3 is thus adapted, under normal operating conditions, to heat the working fluid.

[0032] The external heat exchanger 3 may be formed by multiple structures or, more preferably, by a single structure shared by multiple modules, and even more preferably by all the modules. The type of heat exchanger is known per sé and includes fins or heat exchange protrusions.

[0033] The heat pump unit 1 further preferably comprises at least one internal heat exchanger 4, adapted to exchange heat between said working fluid of all the modules 2 and the single internal environment described above. This internal heat exchanger 4 is thus adapted, under normal operating conditions, to heat the working fluid.

[0034] Also in this case, the internal heat exchanger 4 may consist of multiple structures or, more preferably, of a single structure shared by multiple modules, and even more preferably by all the modules. The type of heat exchanger is known per sé and includes fins or heat exchange plates and preferably varies depending on whether it exchanges heat with a liquid or a gas.

[0035] The heat pump unit 1 further preferably comprises main control means 5 of an electronic type, adapted to control the entire unit 1 and electronically connected to the auxiliary control means 23. The main control means 5 preferably have greater computing capacity than the auxiliary control means 23. Moreover, the main control means 5 may be separate from the auxiliary control means 23. Alternatively, they may consist of the same electronic devices but with different functions and programs.

[0036] As another alternative, the main control means 5 may coincide with the auxiliary control means 23 of one of the modules, programmed differently from the others or simply to which different functions have been assigned.

[0037] Additionally, the heat pump unit 1 preferably comprises at least one sensor 6, in data connection, either direct or indirect, with the auxiliary control means 23 and / or the main control means 5. Preferably, all sensors 6 that are in data connection with the auxiliary control means 23 of the module 2 are indirectly connected to the main control means 5, given the connection between the auxiliary control means 23 and the main control means 5. Sensor 6 is adapted to assist at least in detecting the need for defrosting, as further detailed below.

[0038] The connection between the sensors 6 and the auxiliary control means 23 can be either direct or indirect and may go through the main control means 5.

[0039] In the latter case, advantageously, the auxiliary control means 23 are not provided with connection means, and in particular input / output connection ports, with the sensors 6, which functionally belong to the module 2, but are instead connected to their respective sensors 6 only through the main control means 5.

[0040] The sensors 6 preferably include sensors adapted to detect and measure the temperature. Specifically, they may measure a first temperature T1 of the external environment and, preferably, also a second temperature T2 of the working fluid before it enters the external heat exchanger 3.

[0041] Preferably, there is a single sensor capable of measuring the first temperature T1, whereas, preferably, each module 2 comprises a sensor 6 adapted to measure the second temperature T2 of its own working fluid before it enters the external heat exchanger 3. Additionally, other temperature sensors 6 may be provided in the internal environment and in the heating circuit 21, for example, before and after the compressor 21 and the lamination valve 22.

[0042] Furthermore, in addition to or as an alternative, various sensors 6 may be present to at least assist in detecting the need for defrosting, such as optical sensors on the external heat exchanger 3, humidity sensors, and other known and useful sensors for this purpose.

[0043] The invention includes a new defrosting method for a heat pump unit 1, preferably of the previously described type.

[0044] The defrosting method preferably comprises, first of all, the detection, by means of the auxiliary control means 23 of one of the modules 2, of a need for defrosting.

[0045] Following this detection, the defrosting method includes the activation of a defrosting procedure for said external heat exchanger 3 for all the modules 2. This activation may therefore be controlled by a single module 2, which has detected the need for defrosting, and is however carried out by all the modules 2 simultaneously. Obviously, this activation of the defrosting procedure is also triggered if multiple modules 2 simultaneously verify such a need.

[0046] The termination of the defrosting procedure, however, is controlled exclusively by the main control means 5, either simultaneously for all modules 2 or individually for each module, but in any case, exclusively by the main control means 5.

[0047] The main control means 5 are therefore able to assess whether and when it is the right time to interrupt the defrosting procedure, possibly also supported by the connection with all the auxiliary control means 23 and with all the sensors 24. For example, they may decide to terminate the procedure simultaneously for all modules 2, even if one of the modules 2 is not perfectly defrosted, but, in any case, the overall energy optimization of the unit over time would benefit from it.

[0048] The defrosting method also includes an innovative procedure for verifying the need for defrosting.

[0049] In particular, the defrosting condition is detected, and therefore the defrosting procedure is activated, if, under normal operating conditions (i.e., at least 10 minutes after the unit activation), the second temperature T2 is less than or equal to a first predetermined temperature Ti, for a time period t, which may be non-consecutive, greater than a first predetermined time period t1.

[0050] Additionally, preferably, the time period t is reset if at least one of the following three conditions occurs: The second temperature T2 is greater than a second predetermined temperature T II , for a period of time longer than a second predetermined period t2. The second temperature T2 is between a third predetermined temperature T III and the second predetermined temperature T II for a period of time longer than a third predetermined period t3. The defrosting procedure is completed.

[0051] Preferably, the predetermined values are as follows: First predetermined temperature T I , preferably between -2°C and 2°C, more preferably 0°C. Second predetermined temperature T II , preferably between 11°C and 17°C, more preferably 14°C. Third predetermined temperature T III , preferably between 0°C and 4°C, more preferably 2°C. First predetermined period t1, preferably between 20 minutes and 40 minutes, more preferably between 27 minutes and 33 minutes. Second predetermined period t2, preferably between 1 minute and 5 minutes, more preferably around 2 minutes. Third predetermined period t3, preferably between 15 minutes and 25 minutes, more preferably between 18 minutes and 22 minutes.

[0052] The need for defrosting is also preferably detected if the unit 1 has been running for less than the third predetermined period t3, and if all the following conditions are met: The first temperature T1 is lower than a fourth predetermined temperature Tiv, and The second temperature T2 is lower than a fifth predetermined temperature Tv for a period of time greater than a fourth predetermined period t4.

[0053] Preferably, the predetermined values are as follows: fourth predetermined temperature T IV , preferably between 5°C and 15°C, more preferably 10°C. fifth predetermined temperature Tv, preferably between -5°C and 0°C, more preferably -2°C. fourth predetermined period t4, preferably between 15 seconds and 3 minutes, more preferably 1 minute.

[0054] The defrosting procedure is preferably performed by reversing the flow of the working fluid within the circuit 20, by means of a command given to the compressor 21 and through a valve commonly referred to as a four-way valve, not shown in the drawings but known to a person skilled in the art. In this way, the fluid heats the external heat exchanger 3, causing the melting and / or detachment of frost or ice. Alternatively, dedicated heating means may be provided, such as electric resistances or similar, or other solutions.

[0055] The activation of the defrosting procedure therefore corresponds to the reversal of the cycle, or more preferably to the reversal of the pressure gradient of the compressor 21, while its termination corresponds to a restoration of the usual cycle and gradient.

[0056] The operation of the heat pump unit 1, previously described in structural terms, functions in a known manner and implements the defrosting method when necessary.

[0057] The defrosting method and the heat pump unit 1 according to the invention, as previously described, achieve important advantages.

[0058] Indeed, the said method and the said unit allow for maximizing the energy efficiency of the heat pump unit, implementing a simple and effective method.

[0059] The heat pump unit 1 according to the invention is also economical and robust.

[0060] The invention is subject to variations within the scope of the inventive concept defined by the claims. Within this scope, all details can be replaced by equivalent elements, and materials, shapes, and dimensions may be any.

Claims

1. A method of defrosting in a heat pump unit (1), said heat pump unit (1) comprising a plurality of modules (2) each comprising: - a heating circuit (20) housing a working fluid, - a compressor (21) for circulating said fluid in said heating circuit (20), - a lamination valve (22), internal to said heating circuit (20), - auxiliary control means (23) of an electronic type suitable for controlling at least said module (2); said heat pump unit (1) further comprising: - at least one external heat exchanger (3) suitable for exchanging heat between said working fluid of all said modules (2) and an external environment, - at least one internal heat exchanger (4), suitable for exchanging heat between said working fluid of all said modules (2) and an internal environment, - main control means (5) of electronic type suitable for controlling said unit (1) and in connection with said auxiliary control means (23); said defrosting method being and characterised by comprising: - detecting, by means of said main control means (5) and / or said auxiliary control means (23) of at least any one of said modules (2), a need for defrosting, - the subsequent activation of a defrosting procedure of said external heat exchanger (3) for all said modules (2), - wherein the end of said defrosting procedure is controlled exclusively by said main control means (5).

2. Defrosting method according to any preceding claim, wherein said term of said defrosting procedure is simultaneously controlled for all said modules (2).

3. Defrosting method according to any of the previous claims, wherein said internal heat exchanger (4) of all said units is structurally constituted of a single element.

4. Defrosting method according to any of the previous claims, said main control means (5) also constituting one of said auxiliary control means (23).

5. Defrosting method according to any of the previous claims, wherein said heat pump unit (1) comprises at least one sensor (6), in data connection with said main control means (5) of said module (2), for said detection of said need for defrosting.

6. Defrosting method according to any of the previous claims, wherein at least one said sensor (6) is configured to measure a first temperature (T1) of said external environment.

7. Defrosting method according to any of the previous claims, wherein each of said modules (2) comprises a sensor (6) configured to measure a second temperature (T2) of said working fluid prior to entering said external heat exchanger (3).

8. Defrosting method according to any preceding claim, wherein said need for defrosting is detected if, under normal operating conditions, said second temperature (T2) is less than or equal to a first predetermined temperature (Ti), between -2°C and 2°C, for a period of time (t), also non-consecutive, greater than a first predetermined period of time (t1) between 20 minutes and 40 minutes, said period of time (t) being zeroed if one of the following three conditions occurs: - said second temperature (T2) is greater than a second pre-set temperature (TII), between 11°C and 17°C, for a period of time greater than a second pre-set period (t2) between 1 minute and 4 minutes, - said second temperature (T2) is between a third pre-set temperature (TIII), between 0°C and 4°C, and second pre-set temperature (TII), for a period of time longer than a third pre-set period (t3), between 15 minutes and 25 minutes, - this defrosting procedure is completed.

9. Defrosting method according to any one of claims 8 and 9, wherein said need for defrosting is detected wherein said unit (1) has been running for less than a third predetermined period of time (t3) between 10 minutes and 20 minutes and wherein all of the following conditions are met: - said first temperature (T1) is less than a fourth pre-set temperature (Tiv) between 5°C and 15°C, - said second temperature (T2) is less than a fifth preset temperature (Tv), between - 5°C and 0°C, for a period of time greater than a fourth preset period (t4), between 15 seconds and 3 minutes.

10. Heat pump unit (1) comprising a plurality of modules (2), each comprising: - a heating circuit (20) housing a working fluid, - a compressor (21) for circulating said fluid in said heating circuit (20), - a lamination valve (22), internal to said heating circuit (20), - auxiliary control means (23) of an electronic type suitable for controlling at least said module (2); said heat pump unit (1) further comprising: - at least one external heat exchanger (3) suitable for exchanging heat between said working fluid of all said modules (2) and an external environment, - at least one internal heat exchanger (4), suitable for exchanging heat between said working fluid of all said modules (2) and an internal environment, - main control means (5) of electronic type suitable for controlling said unit (1) and in connection with said auxiliary control means (23), - sensors (6) in direct data connection with said main control means (5), said heat pump unit (1) being characterised by the fact that: - there is a sensor (6) configured to measure a second temperature (T2) of said working fluid before entering said external heat exchanger (3) of each of said modules, - said auxiliary control means (23) are not provided with means for connection with said sensors (6) and are in connection with said sensor (6), suitable for measuring said second temperature (T2) of said module (2) to which said auxiliary control means (23) belong, only through said main control means (5).

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