A Modular Fluid-Fluid Heat Transfer Arrangement and a Method Thereof

The present disclosure relates to a modular fluid-fluid heat transfer arrangement. The present disclosure further relates to a method for controlling a modular fluid-fluid heat transfer arrangement.

Nearly all large, developed cities in the world have at least two types of energy grids incorporated in their infrastructures; one grid for providing electrical energy and one grid for providing space heating and hot tap water preparation. Today a common grid used for providing space heating and hot tap water preparation is a gas grid providing a burnable gas, typically a fossil fuel gas. The gas provided by the gas grid is locally burned for providing space heating and hot tap water. In order to reduce the carbon dioxide emissions there are plans to replace such gas grid with more “green” energy efficient energy systems.

One such energy efficient energy system is cold thermal grids. Cold thermal grids are an evolution of district heating and district cooling systems, where combined district heating and district cooling system with aid of using heat pumps for heating and cooling can provide both cooling, heating and tap water preparation to buildings.

In order to succeed with the replacement of gas grids, where the respective gas burner is replaced by a heat pump, the heat pumps used need to be smaller, less costly and with lower technical complexity, e.g., with fewer and/or less complex sensors for measuring the space heat and tap water energy consumption than presently used heat pumps.

Further, the heat pumps typically require a refrigerant in order to be able to operate as efficient as possible. A drawback with the refrigerants used today is that they have large global warming potential (GWP). A solution for this drawback is to use refrigerants having lower GWP which however have unwanted characteristics setting requirements on the maximum amount of refrigerant allowed in one heat pump in order to be allowed to be placed in certain zones, such as unventilated areas. However, using a small amount of refrigerant may limit the maximum input power, i.e., the compressor capacity, of the heat pump, and so also the maximum output power achieved from the heat pump.

Thus, the conventional heating and/or cooling systems are associated with several drawbacks. There is thus a need in the art for an improvement in this area.

It is an object to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination and solve at least the above mentioned problem.

It is an object of the disclosure to provide an efficient heat transfer arrangement for heating and/or cooling and/or providing tap water to different types of buildings.

Another object is to provide a flexible, but also adjustable, heat transfer arrangement.

Another object is to provide such a heat transfer arrangement which is environmentally friendly.

Another object is to provide such a heat transfer arrangement which is less time consuming to install and/or maintain.

It is also an object to provide a cost-efficient heat transfer arrangement.

It is also an object to provide a compact heat transfer arrangement.

According to a first aspect, there is provided a modular fluid-fluid heat transfer arrangement comprising:

Through-out the application text, the term “modular fluid-fluid heat transfer arrangement” will also be referred to as “heat transfer arrangement” or “arrangement”.

By the term “modular fluid-fluid heat transfer arrangement” is here meant an arrangement which comprises a plurality of heat pump modules which are separate from and independently of each other. Thus, the plurality of heat pump modules may be introduced in a housing or a zone, e.g., in a controlled space in which the plurality of heat pump modules is arranged, without the need of being attached, e.g., fastened, or mounted, to each other. The arrangement may be configured to cover, i.e., being able to heat and/or cool and/or provide tap water to, an area. The area may be the whole, or a part of, the building. Thus, the fluid-fluid heat transfer arrangement may be configured to provide cooling or heating to a building, or a part of a building. If the arrangement is configured to provide heat to the building, the purpose of the arrangement is to supply heat from the cold to the hot side. If the arrangement is configured to provide cooling to the building (i.e. to remove heat therefrom), the purpose of the arrangement is to remove heat from the cold side.

The fluid-fluid heat transfer arrangement may be a fluid-fluid heat pump arrangement configured to provide heat to the hot side fluid for heating the same.

The fluid-fluid heat transfer arrangement may be a fluid-fluid cool pump arrangement configured to remove heat from the cold side fluid for cooling the same.

As readily appreciated by the person skilled in the art, the fluid-fluid heat pump arrangement and the fluid-fluid cool pump arrangement is in principle the same, the only difference being what the end user is interested in to achieve (heating or cooling). However, there may be differences between the two implementations of the general concept with regards to features such as e.g. the temperature range used in the hot and cold side grids. This is further discussed later.

By the term “connecting the modular fluid-fluid heat transfer arrangement to a cold fluid side” is here meant that the first inlet and outlet junction pipes are configured to be physically connected to, or coupled to, the cold fluid side via any kinds of pipes, connectors, or the like. Put differently, the first inlet and outlet junction pipes are configured to be fluidly connected to the cold fluid side such that a cold side fluid is able to be fed in the cold side fluid recirculation path, between the heat transfer arrangement and the cold fluid side. In this context, the first inlet junction pipe is connectable to a hot conduit of the cold fluid side and the first outlet junction pipe is connectable to a cold conduit of the cold fluid side. For typical heating applications of the arrangement, the fluid in the cold conduit of the cold fluid side may be in the range of −10 to 25° C. and the fluid in the hot conduit of the cold fluid side may be in the range of 0 to 40° C. For typical cooling applications of the arrangement, the fluid in the cold conduit of the cold fluid side may be in the range of −10 to 25° C. and the fluid in the hot conduit of the cold fluid side may be in the range of 10 to 50° C.

For typical heating application, the cold fluid side may be an evolution of district heating and district cooling systems, where combined district heating and district cooling system with aid of using heat pumps for heating and cooling can provide both cooling, heating and tap water preparation to buildings. The cold fluid side may be coupled to a downhole heat exchanger, or borehole heat exchanger. For typical cooling applications, the cold fluid side may be a cooling system in the building.

By the term “connecting the modular fluid-fluid heat transfer arrangement to a hot fluid side” is here meant that the second inlet and outlet junction pipes are able to be physically connected to, or coupled to, the hot fluid side via any kinds of pipes, connectors, or the like. Put differently, the second inlet and outlet junction pipes are configured to be fluidly connected to the hot fluid side such that the hot side fluid is able to be transported in the hot side fluid recirculation path, between the heat transfer arrangement and the hot fluid side. In this context, the second inlet junction pipe is connectable to a cold conduit of the hot fluid side and the second outlet junction pipe is connectable to a hot conduit of the hot fluid side. For typical heating applications of the arrangement, the fluid in the cold conduit of the hot fluid side may be in the range of 10 to 50° C. and the fluid in the hot conduit of the hot fluid side may be in the range of 25 to 75° C. For typical cooling applications of the arrangement, the fluid in the cold conduit may be in the range of −10 to 25° C. and the fluid in the hot conduit may be in the range of 0 to 40° C.

For typical heating applications, an input temperature of the fluid to the arrangement may be om the range of 0 to 40° C. and an output temperature of the fluid from the arrangement to the building or parts of the building may be in the range 15 of 25 to 75° C. For typical cooling applications, the input temperature of the fluid may be in the range of 0 to 40° C. and the output temperature of the fluid from the arrangement to the building or parts of the building may be in the range of −10 to 25° C.

For typical heating applications, the hot fluid side may be a heating system, such as radiators or tap water systems, in the building. For typical cooling applications, the hot fluid side may be an evolution of district heating and district cooling systems, where combined district heating and district cooling system with aid of using heat pumps for heating and cooling can provide both cooling, heating and tap water preparation to buildings. The hot fluid side may be coupled to a downhole heat exchanger, or borehole heat exchanger.

By the term “refrigerant circulation path” is here meant a heat pump module loop in which a refrigerant is circulating. The refrigerant is typically circulated through the first heat exchanger unit, the compressor, the second heat exchanger unit and the expander. The expander may be configured to control an amount of refrigerant released into the first heat exchanger unit. The refrigerant may be referred to as a working fluid. The refrigerant may be configured to evaporate and condense when circulating in the heat pump module.

A refrigerant is a working fluid used in the refrigeration cycle of air conditioning systems and heat pumps where in most cases they undergo a repeated phase transition from a liquid to a gas and back again. A particular refrigerant has a phase transition temperature at a specific pressure.

For typical heating and/or cooling applications of the arrangement, the refrigerant should have a phase transition temperature in the range of −30 to 0° C. in a pressure range 1-10 bar. For such applications, the refrigerant may be chosen from the group consisting of: R290, R32, R410A, R470C and R134A.

By the term “control means” is here meant any means of controlling the heat pump module, especially the operation thereof. The control means may be e.g. a microprocessor or a central processing unit, CPU, which is capable of making its own individual assessment based on input data from e.g. sensors. This is an example of an active control means. However, a control means according to the disclosure may alternatively be a socket for operably connecting the heat pump module to an external control unit. In the latter case, the heat pump module is passive, and the decisions are made outside of the heat pump module in the external control unit. Preferably, the control means of each heat pump of the plurality of heat pumps comprises a processor, e.g., a CPU configured to actively control the heat pump modules.

Each heat pump module of the plurality of heat pump modules may have a maximum input power, Pof 1-10 KW, preferably 3-6 kW. Neglecting the much smaller power needed for pumps, sensors etc. in the module, the term “maximum input power” may be approximately the same as a maximum capacity of the compressor, often referred to as compressor power, i.e., the power which is supplied to the compressor during operation at its maximum rated power. Each compressor may be configured to operate with a variable compressor power, wherein the maximum input power is the highest power which may be supplied to the compressor during operation. Accordingly, the associated heat pump module may also be variably operated.

The arrangement may have a maximum arrangement input power. In this context, the “maximum arrangement input power” is the sum of the maximum input powers of all heat pump modules present in the arrangement.

Each heat pump module may be able to produce a maximum output power, Pbased on the associated maximum input power and a coefficient of performance (COP). The COP is a ratio of useful provided heating or cooling to supplied work energy. It is advantageous to have as high COP as possible because it provides to higher efficiency, lower energy consumption and thus lower operating costs.

The arrangement may have a maximum arrangement output power. In this context, the “maximum arrangement output power” is the sum of the maximum output powers of all heat pump modules present in the arrangement.

The heat transfer arrangement may be operating in order to produce a required arrangement output power. The “required arrangement output power” is the power needed to fulfil heating and/or cooling and/or tap water requirements. Thus, the required arrangement output power is the output power needed to provide a required temperature of heating and/or cooling and/or tap water to the building. As readily appreciated by the person skilled in the art, the required arrangement output power may be the same as the maximum arrangement output power but may also be less than the maximum arrangement output power, dependent on the requirements.

Each heat pump module of the plurality of heat pump modules may have a height between 25-45 cm. Each heat pump module of the plurality of heat pump modules may have a width between 15-35 cm. Each heat pump module of the plurality of heat pump modules may have a depth between 45-65 cm.

Each heat pump module of the plurality of heat pump modules may alternatively have a height between 10-50 cm. Each heat pump module of the plurality of heat pump modules may alternatively have a width between 10-50 cm. Each heat pump module of the plurality of heat pump modules may alternatively have a depth between 30-80 cm, or 40-65 cm. In one embodiment, each heat pump module of the plurality of heat pump modules has a height of about 41 cm, a width of about 23 cm and a depth of about 43 cm.

This implies that each heat pump module of the plurality of heat pump modules may be portable. By “portable” is herein means that the dimensions and/or weight of the heat pump module is within limits allowing it to be manually carried to and from a heat transfer arrangement by maintenance personnel without need of special equipment, such as hoists, lifts or the like. This may be advantageous as it allows to introduce an improved maintenance paradigm. Instead of repairing a faulty heat pump on site, the faulty heat pump module may be detached from the heat transfer arrangement and replaced by another heat pump module. This gives advantages in reduced complexity in maintenance.

Each heat pump module of the plurality of heat pump modules may have a weight within the range of 20-40 kg, or 25-35 kg or about 30 kg.

It should however be noted that each heat pump module of the plurality of heat pump modules may have a greater, or smaller, maximum input power than the above-identified ranges. The maximum input power of the respective heat pump module may determine the size of the heat pump module. Thus, it should further be noted that each heat pump module of the plurality of heat pump modules may have greater, or smaller, height, width, and/or depth than the above-identified ranges.

The modular fluid-fluid heat transfer arrangement is advantageous as it provides for a flexible heat pump system. Thus, since each heat pump module of the plurality of heat pump modules is separated from and independent of the other heat pump modules comprised in the arrangement, and that they are connected to each fluid side in parallel, it is possible to design and/or modify the arrangement in different ways. Thus, the different heat pump modules may have different maximum input power such that it is possible to tailor an arrangement based on different requirements, among other things, the size of the building and the required arrangement output power needed for heating and/or cooling and/or providing tap water to the building. This facilitates the provision of being able to provide an efficient heat transfer arrangement for heating and/or cooling and/or providing tap water to different types of buildings.

By arranging the plurality of heat pump modules in parallel to each other, it is possible to continue operate the arrangement although one or more of the heat pump modules may broke or having other problems with running.

At least one heat pump module of the plurality of heat pump modules may be arranged in a respective operating position when in use, from which operating position it may be detachable.

The term “detachable” is here meant that at least one heat pump module of the plurality of heat pump modules are removably arranged in the arrangement. Put differently, at least one heat pump module of the plurality of heat pump modules is arranged in the arrangement in a way such that it is possible to remove and/or replace the heat pump module.

Preferably, each heat pump module of the plurality of heat pump modules is arranged in a respective operating position, when in use, from which operating position it is detachable.

This is advantageous as it allows for removing the heat pump module in an easy way upon maintenance of the heat pump module. Thus, it is possible to remove the heat pump module from the arrangement and maintain and/or service the heat pump module at a different position than within the arrangement. This simplifies maintenance of the heat transfer arrangement. This is further advantageous as it allows for decreasing the required output arrangement power needed, for instance if there is a need to downsize the area which the arrangement needs to cover, without the need of replacing the complete arrangement.

This is yet further advantageous as it allows for replacing the heat pump module with another heat pump module. Thus, the maximum arrangement input power of the arrangement may be easily adjusted by being able to replace the heat pump module to another heat pump module having a different maximum input power than the heat pump module removed from the arrangement.

Thus, instead of having to discard, or maintain, the complete arrangement when one of the heat pump modules has problems, it is possible to discard, or maintain, the specific heat pump module. This provides for both an increased life of the heat transfer arrangement but also a more environmentally friendly solution.

It may also be possible to add further heat pump modules to the heat transfer arrangement. This is advantageous as it allows for increasing the required output arrangement power, for instance if there is a need to expand the area which the arrangement needs to cover, without the need of replacing the complete arrangement.

Each heat pump module of the plurality of heat pump modules may comprise a cold side fluid flow control device configured to control a flow rate of cold side fluid being supplied to each heat pump module from said cold side fluid recirculation path.

This is advantageous as it allows for the cold side fluid flow control device to control, or balance, the flow rate of the cold side fluid. Thus, the cold side fluid flow control device is configured to control the flow of the cold side fluid in the respective heat pump module such that a required output power is achieved.

This is further advantageous as it allows for controlling the flow rate of the heat pump module in an easy and efficient way.