WO2013076348A1

WO2013076348A1 - Ground source heat apparatus

Info

Publication number: WO2013076348A1
Application number: PCT/FI2011/051021
Authority: WO
Inventors: Timo Hulkkonen
Original assignee: Gebwell Oy
Priority date: 2011-11-21
Filing date: 2011-11-21
Publication date: 2013-05-30
Also published as: EP2783169A1; EP2783169A4

Abstract

The invention relates to a ground source heat apparatus which includes a ground source heat pump, a heat recovery apparatus and an energy accumulator (2), which ground source heat pump has a hermetically sealed power unit (1). According to the invention, the power unit (1) is set in a shell construction (5; 6, 7) which is set partially or totally underground and the power unit is liftable as a whole from the shell construction (5; 6, 7).

Description

GROUND SOURCE HEAT APPARATUS

The invention relates to a ground source heat apparatus according to the preamble of claim 1.

Solar heat radiation is accumulated in the ground, bedrock and water bodies in summertime. Energy accumulated during summer can be transferred by a solution circulated via a pipe or equivalent dug to the ground or rock or embedded to the water body to an evaporator. Energy is brought to the evaporator located within a ground source heat pump via the solution irrespective of the receiving circuit having been arranged as a closed or an open cycle. The closed cycle refers to a pipe or some other heat exchanger in which the same medium circulates and to which energy from the ground transfers via the pipe surface. The open cycle refers to a system in which water of a water body or groundwater is supplied directly to the secondary side of the evaporator and returned back freely to the nature.

In ground source heat pumps, generation of heat is based on a circulation process in which a refrigerant circulating in an apparatus vaporises and condenses. The main components of the apparatus are an evaporator, a compressor, a condenser, and an expansion device controlling the supply of refrigerant, often an expansion valve. In the evaporator, refrigerant vaporises in a temperature lower than that of the surroundings thus binding heat from the surroundings. The compressor sucks low- pressure refrigerant vapour and compresses it to a higher pressure. At the same time, the temperature of refrigerant increases. Vapour in the condenser being in a higher temperature than the surroundings liquefies i.e. condenses thus conveying heat to its surroundings. In the expansion device, the pressure of liquid refrigerant decreases, whereby the liquid transforms into a liquid-vapour mixture and the temperature of the mixture simultaneously decreases.

In theory, heat conveyed by the condenser equals heat bound by the refrigerant in the evaporator and work done by the compressor. In practice, a few percentages of heat transfer to the surroundings via the compressor and the pressure pipe. Contrary to cooling applications, ground source heating aims at transferring all the heat to the condenser and through that to the heating system.

In addition to the main components, the refrigerant circuit of the ground source heat pump can also include other components, such as filters, extra heat exchangers, solenoid valves, return valves, sight glasses etc. A power unit of the ground source heat pump refers to the assembly of components being in connection with the refrigerant circuit. Of its type, the power unit of ground source heat pumps is a gas- tightly (hermetically) sealed system in which the whole refrigerant circuit has been sealed, vacuumised and filled at the factory. Nothing is connected to the refrigerant circuit and it is not touched in any way in connection with the installation of the ground source heat pump. Energy is conveyed to and from the refrigerant circuit indirectly by means of heat exchangers. The evaporator is not located directly to outdoor air or the ground circuit. The condenser is not in the energy accumulator and does not convey heat directly to the air of the space being heated. The power unit of the ground source heat pump does not harvest heat directly from air or convey heat directly to air. On the secondary side of the heat exchangers of the refrigerant circuit, there is a liquid solution. The power unit can be detached and replaced as a whole, the refrigerant circuit remaining untouched.

The power unit of the ground source heat pump harvests energy from the primary circuit by a refrigeration process. Produced energy is transferred to the direct heating system of a building and/or as buffer to the energy accumulator. The ground source heat pump distributes energy to the building via the energy accumulator. It is possible to produce warm service water in the accumulator and it can distribute energy to the heating system of the building. Of energy accumulated in the energy accumulator, energy can be conveyed out momentarily with higher power than it has been produced. The energy accumulator can also be connected with other external energy sources besides the ground source heat pump. External energy can be transferred to the accumulator e.g. via the heat exchanger. The heat pump can include a built-in electric heater as an extra heat source or for emergency operation.

Energy content of the accumulator is affected by the size and available temperature of the accumulator. The maximum temperature of the refrigeration process is limited and varies between different refrigerants. Increasing the temperature of the accumulator by the refrigeration process for increasing the energy content of the accumulator always means weakening the efficiency of the refrigeration process. In practice, the accumulator should be as large as possible for maximising the energy content without weakening the efficiency of the refrigeration process.

A small energy accumulator has a weakening effect on the amount of service water obtained from the accumulator and the length of the loading period of the heat pump. The length of the loading periods of the heat pump compressor affects the lifetime of the compressor. When loading to a small accumulator, the refrigeration process runs for short operating periods. The refrigeration process normalises for a moment at the start of each operating period. Before the normalisation of the refrigeration process, the efficiency of the process is weaker than that of a normal operating situation. The life cycle of compressors is often limited by the maximum number of startings, whereby operating and standby periods as long as possible improve the expected lifetime of the compressor. In traditional ground source heat pumps installed within a building, the size of the energy accumulator is often limited. The size of the accumulator is restricted by the available room space or the size of doors and corridors when transporting the accumulator inside.

Conventionally, ground source heat pumps, heat recovery apparatuses and energy accumulators are located inside a building, whereby they require their own spaces. This pertains some problems. The space reserved for the ground source heat apparatus is often small and, even though the apparatus can be accommodated indoors, the maintenance measures of the ground source heat apparatus can be awkward to perform due to closeness. It is possible that the ground source heat pump gives out noise and causes vibration when operating. Noises and vibration can be conveyed to living spaces thus weakening comfort of living. Furthermore when renovating buildings or renewing heating systems, the buildings rarely have a suitable location for a sizeable energy accumulator or getting it to a suitable space is impossible without pulling down some structures. It is known that separate power unit parts of ground source heat pumps have been located underground. It is also known that separate ground source heat pumps or their partial assemblies have been located underground. These are the so-called split systems in which the refrigerant circuit has not been readily assembled as a hermetic unit when delivered. An object of the invention is to introduce a ground source heat apparatus by means of which the above problems are eliminated. A particular object of the invention is to introduce a ground source heat apparatus for which a building does not require a specific space or there is no need to construct one. An additional object of the invention is to introduce a ground source heat apparatus which does not cause noise or vibration to living spaces. A further object of the invention is to introduce a ground source heat apparatus which is easily maintainable and easily installable.

The object of the invention is achieved with a ground source heat apparatus which is characterised by what is presented in the claims. According to the invention, the power unit of the ground source heat pump is set in a shell construction which is set partially or totally underground, and the power unit is liftable as a whole from the shell construction. The power unit and its heat exchangers can be detached, whereby the interface of the detachment is the secondary side of the heat exchangers. The refrigeration power unit of the heat pump is thus replaceable as a separate section, the other product remaining in place during a possible fault situation or a breakdown caused by ageing. The installation or maintenance of the refrigeration power unit does not require refrigeration- technical work. The invention can be applied for heating arrangements of buildings in places where lack of space prevents the implementation of heating with conventional layouts. Furthermore, a considerable advantage is gained for comfort of living when the noise and vibration caused by the operation of the ground source heat pump can be isolated outside the residential building. Additionally, the use of living square area in new buildings is intensified when there is no need to separately build a space for implementing heating.

It is easy to add to the apparatus various fittings and connection structures for attaching pipings and other devices to the apparatus.

The apparatus is advantageously formed of one or more shell constructions which can be installed on top of each other or beside each other. The accumulator space and the power unit can be located e.g. for transport in separate shell constructions which can be combined in the field to a fixed assembly.

In an embodiment of the invention, the energy accumulator is located in the ground without the ground source heat pump for increasing the energy reserve. The energy accumulator can be located to one construction embedded to the ground and the power unit of the ground source heat pump can be located to another or more constructions embedded to the ground, whereby the connection between separate constructions is easily done.

The construction of the apparatus with its energy accumulators is easily and quickly installable in pipings and other devices or they are easily installable to the construction.

The shell construction advantageously includes an anchorage against the buoyancy of the ground implemented by shapes or otherwise by means of attachments. The invention will now be described in more detail with reference to the accompanying drawing in which

Fig. 1 shows a ground source heat apparatus according to the invention and its construction located partially below the ground surface, Fig. 2 shows the ground source heat apparatus according to Fig. 1 and its construction located below the ground surface and

Fig. 3 shows another ground source heat apparatus according to the invention and its construction located partially below the ground surface.

The ground source heat apparatus according to the figures includes a power unit 1 of a ground source heat pump, a heat recovery apparatus and an energy accumulator 2. The power unit is hermetically sealed. Furthermore, the apparatus includes a piping 4 which is conveyed underground for harvesting heat. According to the figures, the power unit 1 of the ground source heat pump and the energy accumulator 2 are located within a shell construction 5; 6, 7, 8 which shell construction is set partially or totally underground.

The shell construction 5; 6, 7, 8 is in this embodiment a cylindrical and tank-like construction which is embedded to the ground vertically. Its one end includes an openable cover or lid via which the power unit 1 of the ground source heat pump and/or the energy accumulator 2 can be installed within the construction. This end of the construction can be somewhat above the ground level, which facilitates maintenance.

In the embodiment according to Fig. 1, the power unit 1 of the ground source heat apparatus is located above the energy accumulator 2 and they are in the same shell construction 5. According to Fig. 2, the ground source heat apparatus and the shell construction are located outside a residential building and embedded to the ground in the immediate vicinity of the building or at a desired distance from the building. Additionally, the apparatus includes a heating piping 3 conveyed from the energy accumulator to the building which is connected to the building heating network in a way known as such. To a wall of the shell construction is made a hole in which is locatable a fitting. A solution piping underground is run through the fitting and similarly the heating piping 3 conveyed from the construction to the building is run through the fitting. By means of the piping within the construction, the solution coming from the solution piping is conveyed from the fitting via the power unit 1 of the ground source heat pump to the heat exchanger and the liquid heated in the heat exchanger to the energy accumulator 2. Equivalently, the heating liquid is conveyed from the energy accumulator by means of the piping within the construction to the fitting and via that to the heating piping 3 conveyed to the building.

The construction of the energy accumulator is such that the connections and maintenance of the energy accumulator can be done from above the energy accumulator. The connections of the heat pump and the energy accumulator are such that the ground source heat pump is detachable from the energy accumulator when required.

The shell construction protecting the heat pump and the energy accumulator is manufactured of material suitable for the purpose, such as metal or reinforced plastic or other material. The construction can be safely embedded to the ground. The construction protects the ground source heat apparatus from pressing force caused by the ground, humidity and other physical features. Furthermore, the construction enables the maintenance of the ground source heat pump via the cover. Fittings, electric cords and solution pipes coming through the construction and heating pipes conveyed to the building are provided with tight enough lead-ins. The construction is arranged with appropriate air conditioning and removal of condensed liquid. The electrification of the pump is damp proofed. The electrification can be located to the building or above ground in a separate protective housing.

In an embodiment according to Fig. 3, the power unit 1 of the ground source heat pump and the energy accumulator 2 are in separate shell constructions 6, 7, 8 which are at a distance from each other. The energy accumulator 2 is located in one shell construction 6 embedded to the ground and the ground source heat pump is located in two shell constructions 7, 8 embedded to the ground, being at a distance from each other and connected to the energy accumulator in a known way.

The number of the shell constructions can vary in different embodiments of the invention. Additionally, the shape of the shell constructions can vary in different embodiments of the invention.

The invention is not limited to the advantageous embodiment described, but it can vary within the scope of the inventive idea presented in the claims.

Claims

1. A ground source heat apparatus, which includes a ground source heat pump, a heat recovery apparatus and an energy accumulator (2), which ground source heat pump includes a hermetically sealed power unit (1), characterised in that the power unit (1) is set in a shell construction (5; 6, 7) which is set partially or totally underground and that the power unit is liftable as a whole from the shell construction (5; 6, 7).

2. A ground source heat apparatus according to claim 1, characterised in that the apparatus includes one or more shell constructions (5; 6, 7, 8) which are installable on top of each other or beside each other.

3. A ground source heat apparatus according to claim 1, characterised in that the energy accumulator and the power unit are in the same shell construction (5) on top of each other.

4. A ground source heat apparatus according to claim 1, characterised in that the energy accumulator (2) and the power unit (1) are in separate shell constructions (6,

7, 8) which are connectable as a fixed assembly.