DK177725B1

DK177725B1 - A heating/cooling system and a method for operating a heating/cooling system

Info

Publication number: DK177725B1
Application number: DK201200610A
Authority: DK
Inventors: Hesseldahl Søren; Hertel Karsten; Nielsen Peter Gammeljord; Sørensen Bent; Vraa Jesper
Original assignee: Danfoss As
Priority date: 2012-10-05
Filing date: 2012-10-05
Publication date: 2014-04-22

Abstract

A heating/cooling system is provided comprising ventilating means (4) for moving air in and/or out of a building (1), heat recovery means (5) operatively connected to said ventilating means (4), heating means (2a, 3a, 5a), and cooling means (2b, 3b, 5b). Such a system should be operated with low energy consumption and high comfort. To this end said ventilating means (4,) said heat recovery means (5), said heating means (2a, 3a, 5a) and said cooling means (2b, 3b, 5b) are connected to a common controller (8), said controller (8) preventing cooling and heating at the same time.

Description

DK 177725 B1 A heating/cooling system and a method for operating a heatinq/cooling system 5 The present invention relates to a heating/cooling system comprising ventilating means for moving air in and/or out of a building, heat recovery means operatively connected to said ventilating means, heating means, and cooling means. Said ventilating means, said 10 heat recovery means, said heating means and said cooling means are connected to a common controller, said controller preventing cooling and heating at the same time.

15 Furthermore, the invention relates to a method for operating a heating/cooling system, said system comprising ventilating means for moving air in and/or out of a building, heat recovery means operatively to said ventilating means, heating means, and cooling means, where 20 cooling and heating at the same time is prevented.

Controllers for controlling heating/cooling systems are generally known. A wireless air-conditioning control system is known from US 5927599A. The patent describes 25 the problem in relation to thermal inertia in an air-conditioning system.

US 2004134205 A1 describes a multi-type air-conditioner with one or more outdoor units connected to a plurality 30 of indoor units installed in respective rooms, and operative only in one mode of cooling or heating for controlling room temperatures.

The legal requirements concerning the energy efficiency 35 of newly constructed buildings have been considerably -2- DK 177725 B1 tightened over the last few years. Thermal installation of the buildings is one attempt to fulfil the requirements. Thermal building insulation reduces heat losses out of the building. However, it reduces or prevents 5 natural exchange of air via joints, cracks or the like.

Air that is moist and polluted with carbon dioxide, harmful substances, and odour is no longer replaced which can lead to the formation of mildew and to health problems such as headaches and asthma. Therefore, it is 10 usual to install a ventilation system.

Air extraction takes place in the rooms which are most subjected to moisture and odour, e.g. the bathroom and the kitchen. Fresh air is channelled into e.g. living 15 rooms and bed rooms. The ventilating means are operatively connected to heat recovery means. The flow pattern through the heat recovery means depending on the type of heat exchanger, where, route flow, counter flow, parallel flow, cross flow and cross counter flow 20 are among the most well-known. The heat recovery means heats the fresh air coming from the outside using heat extracted from the exhaust air. The building thus retains the majority of its heat energy.

25 In some instances it is possible to use the ventilating means for cooling the building. One example relates to summer nights, when the outdoor temperature is lower than the indoor temperature. In this case, the heat recovery means can be bypassed to create more pleasant 30 temperatures in the building by using the cool night air.

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The object underlying the present invention is to operate a heating/cooling system with low energy consumption, higher comfort in terms of e.g. better control of temperature and higher convenience as both energy sav-5 ings and comfort is automatic without the need of user interaction.

This object is solved with a heating/cooling system according to claim 1.

10

Since heating requires energy and in most cases cooling requires energy as well a waste of energy is avoided arising from simultaneously heating and cooling. Since the controller is connected to all relevant means re-15 sponsible for the heating and/or cooling it is informed about the operation condition of each means so that the controller reliably can prevent the simultaneous operation of means heating a room and of means cooling a room. Means for heating a room can e.g. be radiators or 20 heating floor. The heating source can e.g. be boiler, district heating, heating pump, etc. The heat recovery means can be used as heating means as well. Means for cooling can be for example bypassing the heat recovery ventilation, whereby the ventilation means are alone 25 Furthermore in addition to bypassing the heat recovery ventilation, a geothermal surface can be used in which brine is exploited to cool down outdoor inlet air. Furthermore, means for cooling can be the radiator or heating floor with cooling water. The cooling source 30 can e.g. be chiller, district cooling, heating pump etc. A hydronic controller can be used controlling both heating and cooling, for both radiators and floor heat- -4- DK 177725 B1 ers. With heat pump and radiator thermostats only the hydronic controller can be left out.

Said controller disables bypassing the heat recovery 5 means when a heating operation is on. When for example in a summer night the outdoor temperature is lower than the indoor temperature, the ventilating means without the heat recovery means can be used to blow cooler air into the building. In the case where there is a general 10 need of a higher indoor temperature and the heating operation is on the controller secures that the incoming cooled air will pass through the heat recovery means to save energy.

15 Furthermore, said controller establishes a dead time between an end of a heating operation and a start of a cooling operation and/or between an end of a cooling operation and a start of a heating operation. This means that a room is not switched directly from heating 20 to cooling or vice versa. The dead time at least partly enables a natural transition between a higher temperature and a lower temperature or vice versa. This saves energy as well.

25 Preferably said dead time is chosen depending on an inertia of said heating means, said cooling means, and said heat recovery means. For example, a floor heater has a much larger inertia than a radiator. Therefore, the dead time for a floor heater could be higher than 30 the dead time for a radiator.

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When dead time between heating and cooling is larger than said dead time between cooling and heating, it is taken into account that the inertia of cooling means is often smaller than the inertia of heating means.

5

Preferably said cooling means comprise different cooling sources, at least two of said cooling sources differing in costs of cooling power, said controller prioritizing a cooling source having lower costs. The 10 costs of cooling power result often from energy consumption. For example, using the ventilating means as cooling unit when the outdoor temperature is low is cheaper than the use of an active cooling needing a compressor and a coolant circulation.

15

Preferably said heating means and/or said heat recovery means are controlled with respect to a heating set point and said cooling means and/or said heat recovery means are controlled with respect to a cooling set 20 point, said heating set point and said cooling set point being offset relative to each other. This offset of the set points is preferred because people typically are lighter dressed in the cooling season and aiming for the heating set point would just create discomfort 25 and energy waste. The offset value can be in the range between 0 and 5 K preferably 2 K.

The task is solved with a method for operating a heat-ing/cooling system according to claim 5, wherecooling 30 and heating at the same time is prevented.

Such an operating mode saves energy.

-6- DK 177725 B1 A building can have one or more heating/cooling systems. The cooling and heating at the same time is prevented within one system. It is possible that a first 5 system in a building uses heating and a second system uses cooling as long as the two systems are operating separately.

A dead time is established between an end of a heating 10 operation and a start of a cooling operation and/or between an end of a cooling operation and a start of a heating operation. The temperature of the heating means and/or the cooling means have a certain time to equalize their temperature with the ambient temperature.

15

Preferably said dead time is chosen depending on an inertia of said heating means, said cooling means, and said heat recovery means. As mentioned above, the inertia of these means is not always the same so for exam-20 pie a floor heater requires more time to equalize its temperature with the ambient or room temperature than a radiator.

The dead time between heating and cooling is larger 25 than said dead time between cooling and heating. This is due to the fact that cooling means usually have a lower inertia.

Preferably said cooling means comprise different cool-30 ing sources, at least two of said cooling sources differing in costs of cooling power, a cooling source having lower costs being prioritized. When for example the DK 177725 B1 -7- ventilating means are used and the air blown into a building is not guided through the heat recovering means, the temperature of this air stream is directly transmitted into the room to be cooled. This is a low 5 cost cooling method since only ventilating power is required. However, when the outdoor temperature is high, other means for cooling are required having a higher energy consumption. The highest energy consumption could be required by a cooling circuit using a coolant 10 pumping. The next step would be passive cooling for a heat pump. The prioritizing of the "cheapest" cooling unit therefore saves energy.

Preferably said heating means and/or said heat recover-15 ing means are controlled with respect to a heating set point and said cooling means and/or said heat recovery means are controlled with respect to a cooling set point, said heating set point and said cooling set point being offset relative to each other. Since the 20 heat recovery means can be used for heating (for example in winter) or for cooling (for example in summer) it can be controlled with respect to the heating set point as well as with respect to the cooling set point.

The heating set point is chosen lower than the cooling 25 set point since most people typically are lighter dressed in the cooling season.

An example of the invention will now be described in more detail with reference to the drawing, wherein:

Fig. 1 is a schematic illustration of a heat-ing/cooling system and 30 -8- DK 177725 B1

Fig. 2 is a flow chart for a heating/cooling method.

Fig. 1 schematically shows a building 1 in which a ra-5 diator 2 and a floor heater 3 are installed. Furthermore, the building 1 comprises ventilating means 4 for drawing air out of the building 1 or for blowing air into the building 1 depending on the requirements. Heat recovery means 5 are operatively connected to the ven-10 tilating means 4. To facilitate understanding, the heat recovery is labelled 5a when used as heating means and 5b when used as cooling means. 5a heat recovery as heating means could e.g. be done by heat recovery and 5b heat recovery as cooling means could e.g. be done 15 by bypassing the heat recovery

To facilitate understanding, the radiator 2 is labelled 2a when used as heating means and 2b when used as cool-20 ing means. Similar is the heating floor 3 labelled 3a when used as a heating means and 3b when used as cooling means.

The heating source 9 can e.g. be boiler, district 25 heating, heating pump etc. Ventilation means 4 and geothermic surface means 6 are energy sources that can both heat and cool.

The cooling means can be the radiator 2b or the heating 30 floor 3b with cooling water or 5b with cooling air.

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The cooling source 10 can be e.g. chiller, district cooling, heating pump etc. Ventilation means 4 and geothermic surface means 6 are energy sources that can both heat and cool.

5

The cooling means having different energy or cost requirements. The simplest and cheapest cooling would be ventilation 4 alone using 5b as cooling means. The next more expensive arrangement would be the ventilating 10 means 4 using heat recovery as cooling means 5b combined with geothermic surface means 6. The next step would be cooling with a cooling source 10.

A hydronic controller 7 can be used controlling both 15 heating and cooling, for both radiators 2 and floor heater 3.

The radiator 2(a,b) the floor heater 3(a,b), the ventilation means 4, the heat recovery means 5, the geother-20 mal surface 6 and the hydronic controller 7 are all connected to a common controller 8. The controller 8 controls the operation of the means mentioned above.

The controller 8 prevents cooling and heating at the 25 same time.

When using heat recovery with cooling means 5b so that the ventilating means 4 blow air having cooler outdoor temperature into the building 1, the radiator 2 and the 30 floor heater 3 do not operate so that no energy is wasted. The heating/cooling system designed for a house -10- DK 177725 B1 with several rooms can allow cooling in some room and heating in other rooms.

The example in Fig. 1 shows a building 1 having only 5 one room. The heating/cooling system is in the simplest embodiment limited to a single room. However, it can be used for a plurality of rooms, for example in a house in which air is extracted from the bathroom and the kitchen and fresh air is channelled into living rooms 10 and bed rooms. In this case, the heating/cooling system is designed for the temperature control in a house.

Such a system may allow cold summer air to be channelled into bed rooms and living room and extract air from the bathroom. The system may allow the bathroom as 15 a special room to be heated. If a building comprises several apartments, each apartment can be considered as a single system. However, it is also possible to combine more than one apartment to a system.

20 In the example shown in Fig. 1 the controller 8 is positioned remote from the building 1. However, it is clear for the expert that the controller 8 can be positioned within the building 1.

25 The connecting lines between the controller 8 and the means 2-10 are shown as physical lines. However, a wireless communication is possible. The controller 8 can be equipped with a screen covering among others means 2-10. It could even be possible to communicate 30 with the controller 8 from the outside via mobile phone or internet.

DK 177725 B1 -li-

In order to ensure that heating and cooling isn't pending, cooling at one time, heating right after, and so on a quarantine period or dead time is introduced.

There can't be cooling in a room before the dead time 5 since last heating effort has expired. There can't be as well heating in the room before the dead time since last cooling effort has expired.

The dead time varies dependent of the cooling/heat 10 emitters inertia. For example, the dead time for the floor heater can be 5 hours. The dead time for the radiator can be 1 hour and the dead time for the heat recovery means 5 can be 1 hour.

15 In mixed systems, the means that is going to be activated, is delayed. For example, when the floor heater 3 is combined with the heat recovering ventilation using the ventilating means 4 and the heat recovery means 5, the floor heater 3 can be activated less than 5 hours 20 before the heat recovery unit as cooling means 5b has been activated and the heat recovery as cooling means 5b can be activated less than 1 hour before the floor heater 3 has been turned off.

25 The heating means 2a, 3a are operated to reach a predetermined heating set point. The cooling means 2b, 3b, 5b, are operated to reach a predetermined cooling set point. Since people typically are lighter dressed in the cooling season, the heating set point and the cool-30 ing set point are offset relative to each other. For example, a heating set point can be chosen at 21°C and the cooling set point can be chosen to 23°C. In this -12- DK 177725 B1 case, the offset is 2 K. The offset value can be adjusted between 0 and 5 K.

Cooling can be deselected in one or more rooms of the 5 building 1. This could typically be bathrooms, where heating (or at least no cooling) is preferred the entire year.

A hydronic controller can either control hydronic cool-10 ing or heating. This means that there cannot be cooling in any room of the system before all cooling selected rooms have finished heating. Whenever all heating has stopped, the rooms where the individual dead time has expired will start cooling immediately.

15

There can be cooling in cooling-selected rooms despite cooling-deselected rooms. With multiple hydronic controllers it is possible to heat in some rooms, and cool in others. However, in this case these rooms should not 20 influence each other. The building should be divided into separate zones or systems, for example a cooling zone and a heating zone.

In this case it would be necessary to use more than the 25 one ventilating means 4 and the heat recovering means 5 since usually it is not possible to divide the supply air to individual rooms. The user should be warned when deselecting cooling in individual rooms, that it might mean that cold air can be supplied into rooms where 30 heating is required. However, such a situation will be very rare.

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As mentioned above, cooling sources or units are implored having different energy or cost requirements.

The most simplest cooling unit would be the ventilating means 4 using heat recovery as cooling means 5b. The 5 next more expensive arrangement would be the ventilating means 4 using heat recovery as cooling means 5b combined with geothermic surface means 6. Furthermore, the next step would be passive cooling for a heat pump (circulating brine over an exchanger). Finally, an ac-10 tive cooling for a heat pump could be used.

In this case, the controller 8 uses the "cheapest" cooling unit in a first priority, as long as this cooling unit fulfils the temperature requirements. With the 15 different cooling units mentioned above, the order of priority is as an example used in the following algorithm:

The heat recovering ventilation uses bypass cooling as 20 the average room over-temperature (actual room temperature minus set point) in all cooling-selected rooms exceeds the average cooling set point. Other (possible) cooling sources are implored if their individual cooling set point is exceeded.

25

Heat is prioritized over cooling. Cooling is not the primary target with the cooling sources as it would be with air conditioning. This means that wherever there is a conflict between heating and cooling, heating is 30 prioritized.

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Fig. 2 shows a flow chart for the heat recovery ventilation method.

With a system described above increased comfort can be 5 achieved through better controlling of temperature. The system has less energy consumption because energy production corresponds to the energy needs. The installation is easier with one common controller and automatic regulation (combined and intelligent controlling). The 10 system is automatic meaning that the user is not troubled with concerns about inefficient control of the indoor climate.

Claims

1. A heating / cooling system with ventilating means (4) for moving air in and / or out of a building (1), 5 heat recovery means (5) operably connected to the ventilating means (4), heating means (2a, 3a) , 5a) and refrigerants (2b, 3b, 5b), whereby these ventilating means (4), heating means (2a, 3a, 5a), and refrigerants (2b, 3b, 5b) are connected to a regulator (8) , whereby the controller (8) prevents cooling and heating at the same time, characterized in that the controller (8) establishes a dead time between the end of a heating operation and a start of a cooling operation and / or between the end of a cooling operation and a start of 15 is a heating operation whereby the dead time between heating and cooling is longer than the dead time between cooling and heating.

The system according to claim 1, characterized in that the dead time is selected in response to an inertia of the heating means (2a, 3a, 5a) and the cooling means (2b, 3b, 5b).

The system according to any one of claims 1 to 2, characterized in that the refrigerants (2b, 3b, 5b) comprise 25 different cooling sources (4, 6, 10), whereby at least two of the cooling sources (4, 6, 10) have different costs for cooling performance, and the controller prioritizes a cooling source (4, 6, 10) with lower costs.

The system according to any one of claims 1 to 3, characterized in that the heating means (2a, 3a, 5a) are controlled according to a heat setting point and the cooling means (2b, 3b, 5b) are regulated. according to a cooling set point, whereby the heat setting point and cooling set point are offset relative to each other.

A method of operating a heating / cooling system comprising ventilating means (4) for moving air in and / or out of a building (1), heat recovery means 10 (5) operatively connected to the ventilating means (4). ), heating means (2a, 3a, 5a), and refrigerants (2b, 3b, 5b), where cooling and heating are prevented at the same time, characterized in that a dead time is established between the end of a heating operation and the start of a cooling operation. and / or between the end of a queue operation and the start of a heating operation, whereby the dead time between heating and cooling is longer than the dead time between cooling and heating.

The method according to claim 5, characterized in that the dead time is selected depending on an inertia of the heating means (2a, 3a, 5a) and the cooling means (2b, 3b, 5b).

The method according to any of claims 5 to 6, characterized in that the refrigerants (2b, 3b, 5b) comprise different cooling sources (4, 6, 10), whereby at least two of the cooling sources (4, 6, 10). ) has different cooling performance costs, and the regulator prioritizes a lower cost cooling source (4, 6, 10). 30 - 3 - DK 177725 B1

The method according to any of claims 5 to 7, characterized in that the heating means (2a, 3a, 5a) are regulated according to a heat setting point and the cooling means (2b, 3b, 5b) are regulated according to a cooling-5 setting point, whereby the heat setting point and the cooling set point are offset relative to each other.