WO2010147492A2

WO2010147492A2 - Method of heating of the residential buildings and a heating system for the residential buildings

Info

Publication number: WO2010147492A2
Application number: PCT/PL2010/000048
Authority: WO
Inventors: Krzysztof Tabedzki
Original assignee: Krzysztof Tabedzki
Priority date: 2009-06-19
Filing date: 2010-06-17
Publication date: 2010-12-23
Also published as: PL388321A1; WO2010147492A3; PL219117B1

Abstract

Electrical energy, preferably photovoltaic energy stored in a buffer, is converted to heat in heat pump compressor (2), while the heating medium from the heat pump compressor is divided into two streams, of which one is directed to high heat capacity heaters, preferably to floor heaters, and the other is directed to small heat capacity and quick convection heaters, preferably with forced circulation of heated air. The individual blocks of the heating system work together by means of heat transfer ring (3), to which heat pump (2) and at least two heat outflows, preferably in the form of buffers, are connected. Heat buffer (20) is a low temperature supplier of the floor heating installation (21) while heat buffer (30) is the supplier of fan coil units (31). A ground or water heat exchanger (5) is connected to heat pump (2); heat pump (2) is powered with electrical energy, preferably from photovoltaic cell (1) by means of electrical energy buffer (7).

Description

Method of heating of the residential buildings and a heating system for the residential buildings

The invention relates to a method of residential building heating and a heating system for the residential buildings.

A generally known and often used method of room heating incorporates heat generated by a boiler fired by gas, fuel oil or solid fuel, which travels to rib or panel radiators mounted on walls, most often on the walls under the windows.

A generally known and often used method of room heating incorporates heat generated by a boiler fired by gas, fuel oil or solid fuel, which travels to floor heaters.

A generally known and often used method of room heating incorporates electrical energy supplied to the heated space where it is converted to thermal energy in electric heating equipment or resistance elements mounted in the floor.

A generally known and often used method of room heating incorporates heat pumps where heat pumped from an external geothermal source is supplied to heating coil cast in the cement screed.

A generally known and often used method of room heating incorporates heat pumps where heat pumped from an external geothermal source is transferred to an air duct through which air from heated rooms flows. This air is heated in the duct by a central convector of the heat pump and subsequently the heated air is again distributed in the heated rooms.

A generally known and often used method of room heating incorporates heat generated in a boiler fired by a renewable fuel (biomass), e.g. straw bricks or wood logs in the form of a fireplace with a water jacket in which the heat is supplied to a hot utility water tank and to central heating radiators.

The methods of room heating presented above have both advantages and disadvantages.

When rib, panel or similar radiators are used to heat room, a problem of conflict appears. The lower the boiler operating temperature, the greater the efficiency of fuel conversion into heat in boilers, particularly in gas boilers. The higher the temperature of the heating medium and the smaller the heat capacity, the higher the calorific effect of the radiators. Presently an option compromising between the lowering of boiler operating temperature and increasing the convection area of radiators is most often used.

When heat is distributed to the rooms by means of these heaters, energy consumption can be reduced when temperature is lowered at a pre-defined time, e.g. when household residents are at work. The thermal response of the heating system to the reduction of temperature is usually felt in the rooms after several minutes. However, the heating parameter maintained in the installation is decisively higher than in the case of floor heating.

A method frequently used to increase the efficiency of fuel consumption involves reduction of the temperature of the heating medium and use of floor heating supplied with a low temperature medium. However, a floor heater has a very large thermal inertia - the effect of the change of the heating parameter is felt after a few hours. Therefore, although a higher calorific effect of the system is achieved, it is not possible to quickly adjust the temperature.

Low gross efficiency of electric resistance heating is its basic drawback, irrespective of how heat is distributed in rooms. Furthermore, this solution is not ecological, particularly in Poland - consumption of electrical energy generated by conventional energy sources contributes to the greenhouse effect. And the delivery of electrical energy to the building is connected with considerable losses of energy during transmission. If the same quantity of fuel were burnt in a modern local boiler, used to generate the same gross electrical energy, more heat would be obtained than the heat obtained from this electrical energy converted into heat in resistance radiators. Although the temperature of rooms can be easily adjusted when electrical heaters of a small heat capacity are used, they are rarely used because of high energy costs.

The use of a central heat pump with an air outlet to heat rooms of a flat, although it has an advantage similar to that produced by radiator heating, namely quick response, and it lends itself well to temperature reduction, has one basic drawback - air between rooms is mixed with the micro flora, germs and bacteria present in the rooms.

A solution without this drawback consisting in the use of separate heat pumps in each heated room is very expensive.

The use of a central heat pump to supply heat to the floor heating system has all the drawbacks of floor heating described above.

The use of a heating boiler in the form of a fireplace with a water jacket has a characteristic drawback - it is not possible to temporarily adjust its thermal power. A fireplace requires careful addition of fuel and is characterized with a high irregularity of burning and, consequently, instability of the process, which results in momentary jumps of power; steam is often produced and heat is exhausted into the atmosphere. Adjustment of radiator temperature is almost impossible - when the fuel in the fireplace is burnt, the heating installation gets very hot; it if often overheated.

The purpose of this invention is to show how the efficiency of heat sources can be most effectively used, how the heat sources can work in a stable way while at the same time ensuring a complete reduction of energy losses through an effective, quick, dynamic and selective adjustment of temperature in individual rooms.

It is also the purpose of the invention to describe a technological system, which can help practically implement the method described above.

The essence of residential building heating consists in the conversion of electrical energy, particularly photovoltaic energy stored in the buffer, into heat in the heat pump compressor; the heating medium produced in the heat pump compressor is split into two streams - one is sent to high capacity heaters, preferably floor heaters, while the other to small capacity and quick convection heaters, preferably with forced circulation of heated air. It is advantageous when the split of the heating medium made by means of stream distributor, preferably three-way valves, is made in a proportion resulting from the current demand for thermal power of individual heaters.

It is advantageous when the heating medium flowing in at least one of the streams is first stored in the heat buffer and subsequently, by means of this buffer, it is directed to the heater.

It is further advantageous when excess power of the heat pump compressor is stored in an additional heat buffer.

It is advantageous when in the case of a smaller temporary demand for heat the capacity of heat pump compressor is reduced by changing the energy form, using an electronic power converter, and electrical parameters of the conversion energy, preferably voltage and/or frequency.

It is also advantageous when by reducing the heat capacity of the heat pump compressor the capacity of pumps that pump a photovoltaic heating medium and/or geothermal heating medium is also reduced.

It is advantageous also when in order to obtain a stable temperature of the streams supplying heat to the floor heaters and/or convectors the streams directed to these heaters are mixed with return streams from these heaters.

It is advantageous when before the geothermal heat is supplied to the heat pump it is directed to the overheated rooms from which recovered heat is directed to the heat pump.

Furthermore, it is advantageous when cool air, before it is discharged from the heat pump to the geothermal source, is first directed to the overheated room in order to cool it down.

The essence of the heating system consists in the following solution - a heat pump and at least two heat outflows, preferably in the form of buffers, are connected to the heat transfer ring. One heat buffer is a low-temperature supplier of the floor heating installation and the other heat buffer is a supplier of fan coil units; a ground or water heat converter is connected to the heat pump powered with electrical energy, preferably from a photovoltaic cell through the ^■ electrical energy buffer.

It is advantageous when a heat buffer, which is a container of hot utility water, is additionally connected to the ring.

It is also advantageous when a ground exchanger is connected to the heat pump; there is a return valve between the ground exchanger and the heat pump to which a cold air reception block, i.e. in the form of fan coil units, is connected.

It is further advantageous when an ecological source of electrical energy is connected to the heat buffer, preferably a fireplace with a water jacket. It is further advantageous when heat buffers and heat pumps are equipped with stream distributors placed in the ring circle.

It is further advantageous when a fireplace with a water jacket is connected to the ring, by means of a stream distributor or by an ejector.

It is furthermore advantageous when a heat exchanger of cold geothermal source is connected to the ring, either directly or by means of a heat exchanger.

The basic effect of the invention is a considerable reduction or even complete resignation from conventional energy sources - heating of rooms is based on renewable ecological energy sources and when effective conditions for the conversion of energy carrying agents into heat are provided and when subsequently this heat is transferred to the heated rooms when heat losses are minimized. The process is fully automatic.

A significant effect of the use of heat transfer technology between the units, called "heat ring", consists in a considerable flexibility in heat transfer between heat sources, heat buffers and the heat reception installation. The use of cold geothermal source as a buffer to stabilize heat generation in a fireplace with a water jacket, which is very unstable, is a substantial effect. Heat from the fireplace "ejected" into the buffer is again transferred to the heating installation at the time when the heat pump is actively used.

Additionally, heated rooms can be air conditioned in summer without any additional investment and operating costs.

The solution to the problem of an economic use of energy to heat a residential building had to comprise three fundamental, seemingly contradictory relations:

• The lower the temperature of the heating medium, the higher the thermal efficiency of the heat source - therefore use of large area low temperature heaters is most advantageous.

• The smaller the difference between room temperature and outside temperature the lower heat losses - therefore it is advantageous when low temperature of rooms is maintained for as long as possible and is increased only when household residents are at home.

• The higher the temperature of the heating medium and the smaller the thermal efficiency of the heater, the greater the heat capacity of heaters.

Reduction of costs was obtained thanks to a cascade of heating devices — a heat pump and a boiler fired with a renewable fuel. Since in our climate demand for peak power of the heating system is only from several to two dozen days a year, the use of the heat pump-fireplace with a water jacket cascade helps to reduce investment costs - a smaller power heat pump and a smaller power photocell system can be purchased. A buffer accumulating energy obtained from a photovoltaic cell can be reduced - the fireplace with the water jacket, operated by the residents, can be used to generate heat in winter afternoons and evenings. A specific warm atmosphere inside the house with a flickering flame of the fireplace is an additional effect.

The flexible control of heat transfer between heat sources and receptacles and indirect heat buffers was obtained by introducing a heat transfer employing a "circular circulation of the thermodynamic medium", subsequently called a "heat ring" between heat sources and heat receptacles.

The invention is described in greater detail with the help of the examples illustrated in the drawing, wherein the Fig.l, Fig.2, Fig.3 and Fig.4 show four different heating installations.

Example 1

Heat pump 2 is supplied with geothermal heat from a cold source of geothermal energy by means of ground exchanger 5, and with electrical energy from photovoltaic cell i by means of electrical energy buffer 7, in which parameters of this energy are stored and transformed, relative to the demand of heat pump compressor 2.

Heat generated in heat pump compressor 2 is distributed between three heat buffers JO, 20 and 30 by means of heat ring 3 equipped with stream distributors 4, for example three-way valves, which can direct the stream of the thermodynamic medium (heat carrier) flowing in the ring to each of the buffers.

Heat buffer 20 supplies heat to the low temperature floor heating installation 21 in the building. As the heat is used by the floor heating installation, thermodynamic medium in heat buffer 2J_ of this installation is heated within the range from Tl_nUn - (when the heat stream in the ring is switched to buffer 20) - to TI_m3x — (when the heat stream in the ring is disconnected from buffer 20). Because of considerable thermal inertia of floor heating installation 21, the average temperature of buffer 20 is set depending on the weather and maintained at such a level so as to obtain the service temperature of rooms during the absence of household residents at, e.g. 17°C.

Heat buffer 3_0 supplies heat to the installation of fan coil units 3_1 used to quickly heat individual rooms of the building. As heat is used by fan coil units 31, the thermodynamic medium in heat buffer 30 is heated in the range from T2_πώl (heat stream is switched from the ring to buffer 3JJ, to T2_max (connection of heat outflow/buffer to the supply of heat from the ring by connecting stream distributor 4 of this buffer 30 to ring circulation). Because of the small thermal capacity of fan coil units 3_L when residents are not at home a low average temperature is maintained, e.g. the same as in heat buffer 20 of floor heating installation 2L When residents return home, temperature is increased by e.g. 15°C in order to get a quick response to the changed temperature for a specific room from the service temperature to the temperature of heat comfort, chosen by a given user. When residents move to another room, a fan coil unit in the previously occupied room is switched off and the fan coil unit in the presently occupied room is switched on.

As there are two separate heating systems, namely a floor heating system (heat buffer 20 and floor heating installation 21_), which supply most of low service temperature heat to the rooms and the system of fan coil units characterized by small thermal inertia (heat buffer 30 and installation of fan coil units 3J_), to which a small part of the heat demanded by the room is supplied by a thermodynamic medium with a slightly higher temperature, the effect of room heating with thermal comfort is obtained when mainly low temperature heat is supplied since the quantity of heat supplied by means of the installation of fan coil units 31, supplied with medium temperature heat, is proportionally small. Rooms selected in space and time are only heated by a few K degrees, e.g. from T=17°C maintained by the floor heating system to T=22°C, i.e. by Delta T=5°K only, when, for example, at the outside temperature of -10⁰C, floor heating installation 21 maintains low temperature heating of rooms at temperature difference Delta T=27^°K.

Heat buffer JO is a tank of hot utility water. In view of the cyclic availability of solar radiant energy it is intensively heated during the day. It also performs another important function during autumn and spring when heat used to heat rooms is smaller than during winter. Since frequent switching on and off of heat pump 2 is disadvantageous, during the small demand for heat to heat rooms heat buffer 20 of floor heating installation 21 or heat buffer 30 of fan coil units 31 is heated in short time intervals. In order to prevent switching on and off of heat pump 2 in such conditions of heat reception, when a given buffer has been heated the valves of stream distributors 4 of heat ring 3 cut this buffer off heat ring 3_ and switch on buffer 10 of hot utility water tank, which is then heated by heat pump 2, which is not switched off. Heat pump 2 is switched off when heat buffer K) of hot utility water tank, which is characterized by considerable heat capacity, has been heated, practically after several minutes of operation. Subsequently, when it again is necessary to heat buffer 20 of floor heating installation 2JL heat from buffer JJ) of hot utility water tank is first moved to buffer 20 by simultaneous opening the stream distributor valve 4 of buffer JO of hot utility water tank and the stream distributor valve 4 of this buffer to heat ring 2. At this time heat pump 2 is inactive. It is switched on when due to the use of heat to heat rooms temperature of buffer 20 or 30 and the temperature of buffer JO of hot utility water tank have dropped. When heat pump 2 has been switched on, it first supplies heat to buffers 20 and/or 30 of the heating installation and then, without interrupting its work, again supplies heat to buffer IjO of hot utility water tank.

Thanks to this use of the capacity of ring 3 to transfer heat between buffers connected to it (10, 20 and 3O)₃ the number of times heat pump 2 is switched on and off is minimized.

In summer fan coil units 32 which cool the room are switched on with switch JJ_. of three-way valves to supply cold air obtained from a cold geothermal source by means of heat exchanger 5. In the solution discussed here it is done by sucking the medium (cold water) from the thermodynamic medium supplied from heat exchanger 5, and circulating it in the primary circuit of heat pump 2. Heat, captured by fan coil units 32 from cooled rooms, heats this thermodynamic medium, which, after heating, is again introduced into the primary circuit before heat pump 2. Therefore heat recovered by fan coil units 32 from the cooled rooms is transferred to heat pump 2 and then pumped by this pump via heat ring 3_to, e.g. buffer Ij) of hot utility water tank JJ) or directly to buffer 30, which supplies heat to the installation of fan coil units 31, which heat the room in, e.g. the northern side of the building.

When heat pump 2 does not heat buffer JJ) of hot utility water tank JJ), heat captured from air conditioned rooms is transported via ground exchanger to cold geothermal source 5 where it gradually, throughout the summer, increases the temperature of heat exchanger 5, and is stored to be used during winter. Paradoxically, the more cold air is supplied to cool air- conditioned rooms in summer, the longer the heat pump operates in winter with more advantageous parameters - the bottom source is warmer.

Example 2

The set up is identical to that in Example 1, with the exception that buffer JJ) of hot utility water tank is additionally heated with the heat obtained from a source of ecological thermal energy, preferably in a fireplace with a water jacket, subsequently in the examples referred to as fireplace 5J₁ and heat ring 3_ is by means of return valve 9 connected with outflow 6 to ground heat exchanger 5 by means of the return of the primary circuit of heat pump 2.

The installation operates in a similar way with the exception that when fireplace 8 begins to work, heat pump 2 is switched on and, in order to protect it against the high temperature of transfer heat in ring 3, it is disconnected from the ring by switching the three- way valve of stream distributor 4 serving heat pump 2, while all heat obtained from the fireplace is moved using ring 1 to buffers 20 and/or 30 and stored first in these buffers and then in buffer 10 of hot utility water tank.

When fireplace 8 finishes its operations, in the first period when buffer 10 of hot utility water tank has an accumulated excess heat, heat buffer 20 of floor heating installation 2J. and/or buffer 30 of fan foil units 3_i is heated via the transfer of heat from buffer JjO of hot utility water tank to these buffers, described in detail in Example 1.

As it is possible that temporarily in buffer 10 of hot utility water tank the temperature is much higher than the standard temperature of hot utility water, it is advantageous to use a valve at the outlet of hot utility water tank to mix hot water from hot utility water tank with cold water so that utility water of the required temperature can be supplied; the required temperature can be maintained with the help of a thermostatic control on the mixing valve.

In the case of excess heat temporarily obtained from fireplace 8, the heat is transferred to ground heat exchanger 5 - it is directed via outflow 6_to the return circuit of this exchanger and by this route to the cold source of geothermal energy by adjusting return valve 9. In this way excess heat obtained in fireplace £ fired with a renewable fuel (wood logs) is buffered in the ground so as not to be "ejected" with the steam into the atmosphere through the safety valve, as usually happens in such installations of fireplace with water jacket.

In summer cold air from the circuit of ground exchanger of cold geothermal source can be directed to buffer 30 of fan coil units 3_1 by means of outflow 6, return valve 9 and ring 3_. Thanks to this solution it is not necessary to use fan coil units 3_1 or cooling fan coil units 32 or any separate switches or heat return valves in the installation circuit as was the case in Example 1. In this solution it must be however remembered that when heat generated by heat pump 2 and then transferred to buffer JO of hot utility water tank via ring 3 is charged, transfer of cold air to buffer 30 of fan coil units 3J, is not possible. This problem has been solved in the example under discussion by coordinating both actions, both with the 24-hour availability of solar electricity, 24-hour variability of outside air (usually it is not necessary to cool rooms down in the morning when the outside temperature is very low and the available photovoltaic energy can be used to heat hot utility water) and the daily activities of installation users.

Example 3

The installation described in Example 3 works like that described in the previous two examples with the exception that fireplace 8 is directly connected to the ring. It is possible to use here either a flow return valve (adjustable three-way valve) or ejection of thermodynamic medium from the circulation of fireplace 8 into the circulation of the ring. Hot thermodynamic medium obtained in fireplace 8 is then injected by the pump serving the fireplace into heat ring 3 where it is sucked by the stream flowing in the ring (the circulation of the heating medium in the ring is forced by the ring circulating pump). When fireplace 8 is in operation, heat pump 2 is disconnected and does not work for ring 3 in order to protect it against overheating with the high temperature of the ring operation in this option of operation. In the first stage of the operation of fireplace 8 buffers 20 and 30 are heated up and subsequently buffer IJ) of hot utility water tank is heated to the maximum temperature. If when the maximum temperature has been obtained fireplace 8 continues to work and supply heat to ring 3, this heat is discharged to ground heat exchanger 5. by means of outflow 6 via adjustable opening of flow return valve 9 (e.g. in the form of a three-way valve coupling the circuit of the geothermal source with heat ring 2). Because of the safe operation of fireplace 8 and in order to maximize the effectiveness of heat generation by fireplace 8, temperature in ring 3_and in the fireplace circulation is maintained at a low level, however sufficient to serve buffers 20 and 30 of room heating, accordingly to the current use of heat by floor heating installation 21 and fan coil units 3J_.

The properties of the installation described in Example 3 are identical to those described in Example 2. The advantage of this solution consists in a greater efficiency of heat accumulation in the source of geothermal energy, obtained from renewable fuel in fireplace 8, and better use of the inner area of the heat exchanger of buffer K) of hot utility water tank, which is particularly important in the mode of operation of ring 2 with heat pump 2. This solution also provides for beneficial choice of the type of buffer JO because of the availability of different hot utility water tanks on the market.

Using an additional heat return valve between sections of the inner heat exchanger of heat buffer K), e.g. a four-way valve, it is possible to combine the solution presented in Fig. 2 with the solution presented in Fig. 3. This combination helps to use the area of inner coils of heat exchanger of heat buffer K) of hot utility water tank much more effectively when working with heat pump 2, structurally provided in the solution shown in Fig. 3, while maintaining the advantages of the system shown in Fig. 2.

Example 4

Example 4 presents another implementation of the invention, in which the installation works in the same way as in Example 3, but fireplace 8 is connected to ring 3_ by means of return valve 4. Stable temperature in the ring is maintained by mixing with the cold air from the cold geothermal source, using heat exchanger 61 installed in outflow 6. Excess heat generated in fireplace S is discharged to the geothermal source via outflow 6 and exchanger 6_1. In summer cold air supplied to the rooms is sucked directly from ground heat exchanger 5 and subsequently directed to the cooling elements of the room (e.g. fan coil units 32) via stream return valve H installed in the circuit supplying heat pump 2 with geothermal cold air.

Claims

1. A method of heating residential buildings, in which electrical energy, preferably photovoltaic energy stored in the buffer, is converted into heat in a heat pump compressor, wherein the heating medium discharged from the heat pump compressor is divided into two streams of which one is directed to high heat capacity heaters, preferably to floor heaters, while the other is directed to low heat capacity and quick convection heaters, preferably with a forced circulation of heated air.

2. A method as in claim 1, characterized in that the division of the heating medium made by means of stream distributors, preferably three-way valves, is made proportionally, depending on the current demand for thermal power of individual heaters.

3. A method as in claim 1, characterized in that the heating medium flowing in at least one of the streams is first stored in the heat buffer and subsequently, by means of this buffer, it is directed to the heater.

4. A method as in claim 1, characterized in that excess heat is stored in an additional heat buffer in order to fully use the heat pump compressor's power.

5. A method as in claim 1 or 2 or 3 or 4, characterized in that in the case of a temporarily smaller demand for heat the capacity of heat pump compressor is reduced by changing, using an electronic power convertor, the form of energy and electrical parameters of the conversion energy, preferably voltage and/or frequency.

6. A method as in claim 5, characterized in that by reducing the heat capacity of the heat pump compressor the capacity of the pumps pumping heating medium of a photovoltaic origin and/or a heating medium of geothermal origin to receptions is reduced.

7. A method as in claim 1 or 2 or 3 or 4 or 6, characterized in that in order to obtain a stable temperature of streams supplying the floor heaters and/or convectors, streams directed to these heaters/convectors are mixed with the primary stream of the heaters/convectors.

8. A method as in claim 1 or 2, characterized in that before geothermal heat is supplied to the heat pump it is directed to overheated rooms, from which recovered heat is directed to the heat pump.

9. A method as in claim 1 or 2, wherein before cold air is discharged from the heat pump to the geothermal source it is first directed to the overheated room to cool it down.

10. A heating system for a residential building in which the heating process is carried out by means of a heat pump, wherein heat pump (2) and at least two heat outflows, preferably in the form of buffers, are connected to heat transfer ring (3). Heat buffer (20) is a low-temperature supplier of floor heating installation (21) while heat buffer (30) is the supplier of fan coil units (31). A ground or water heat exchanger (5) is connected to heat pump (2); heat pump (2) is powered with electrical energy, preferably from photovoltaic cell (1), by means of electrical energy buffer (7).

11. A heating system as in claim 10, characterized in that heat buffer (10), which is a hot utility water tank, is additionally connected to ring (3).

12. A heating system as in claim 10, characterized in that ground exchanger (5) is connected to heat pump (2); there is a return valve (11) of geothermal cold air between heat exchanger (5) and heat pump (2), to which a block of fan coil units (32) is connected.

13. A heating system as in claim 11, characterized in that an ecological thermal energy source, preferably fireplace (8) with a water jacket, is connected to heat buffer (10).

14. A heating system as in claim 10 or 11 or 12 or 13, characterized in that heat buffers (10), (20) and (30) and heat pumps (2) are equipped with stream distributors (4), which are placed in ring (3) or connected to it by ejection.

15. A heating system as in claim 10 or 11, characterized in that fireplace (8) is connected to ring (3) by means of stream distributor (4) or by ejection.

16. A heating system as in claim 14, characterized in that heat exchanger (5) of cold geothermal source is connected to ring (3), directly or via heat exchanger (61).