Patent Description:
Stricter environmental regulations regarding pollutants which have an effect on global warming will strongly impact the air handling systems of tomorrow. Taking into consideration the Global Warming Potential (GWP) of the refrigerant, where the refrigerant R410A often is used, is a very important area for improvement. One of the regulations of great importance, the EU regulation No <NUM>/<NUM> of <NUM> April <NUM> on fluorinated greenhouse gases also known as the EU F-gas regulation, includes a phase down of refrigerants with high GWP values (CO2 equivalents). The objective of the F-gas regulation is to protect the environment by reducing emissions of fluorinated greenhouse gases. All coming generations of air handling systems with an integrated refrigerant system or for heating/cooling of air which is to be sold within the European Union must take into account the phase down schedule in <NUM>/<NUM>.

One solution of meeting the regulation is to use the R32 refrigerant instead of the R410A. This refrigerant is indeed suitable for cooling/heating applications comprising speed-controlled compressors. The GWP for R32 is <NUM>, which is much less than the <NUM> GWP for R410A. Further to this, the Coefficient of Performance (COP) of R32 is superior to many other refrigerants. The COP of R32 is for instance <NUM>-<NUM>% higher than the COP of the R410A refrigerant. The R32 also provides the possibility to manufacture relatively compact refrigeration systems. It has a <NUM>% higher volumetric cooling capacity compared to the R410A refrigerant.

R32 is a rather well-known refrigerant. As a component of R410A it is used in many residential refrigeration systems, but as a pure refrigerant it has not been used until recently. However, R32 is mildly flammable and forms poisonous hydrogen fluoride during combustion. R32 (Difluoromethane, HFC32, Methylene difluoride) is a single component refrigerant. In mixture with R125, the R32 refrigerant has been used to replace the ozone depleting R22 in various small air conditioning systems and heat pumps. The R125 has been used as a fire suspension agent in order to mitigate the flammability of R32. The <NUM>/<NUM>% mixture of R32 with R125 is known as R410A and previously become a popular refrigerant.

According to EU regulations, R32 is classified as an extremely flammable gas, category <NUM> flammable, as it has greater than <NUM>% flammability range by volume. However, contrary to this EU definition, R32 belongs to the mildly flammable A2L class by ASHRAE Standard <NUM> as it has low burning velocity.

If flammable refrigerant, such as for instance R32, would leak into the air handling system and in particular into the air flow stream inside the air handling system, there would be a risk that the refrigerant could ignite, due to various sources of ignition. Furthermore, when an air flow stream including leaked refrigerant exits the air handling system and enters the premises to be cooled/heated, there would be a risk that the refrigerant could ignite in proximity to human beings.

One prior art is disclosed in the <CIT> which discloses a heat source unit comprises: a housing provided with a machine chamber which houses a compressor and an expansion valve and in which a ventilation opening for enabling ventilation with outside air is formed, the housing being also provided with a heat exchange chamber which houses a heat source heat exchanger and also houses a blower which causes air to flow through the heat source heat exchanger; a control box disposed within the housing at a position where an air current generated by the blower passes; a refrigerant concentration detection means disposed within the control box and detecting the concentration of a refrigerant; and a control circuit disposed within the control box and controlling the blower. Upon detecting the leakage of the refrigerant on the basis of a value detected by the refrigerant concentration detection means, the control circuit controls the blower so that the volume of air flowing through the control circuit is the maximum volume of air which the blower can cause to flow through the control box.

It is therefore desirable to accomplish an air handling system that reduces the risk of ignition of refrigerant and subsequently an explosion and/or a fire due to this.

An objective of the present invention is thus to accomplish an air handling system that reduces the risk of leaking refrigerants into the air flow stream in the air handling system, or that reduces the amount of leaking refrigerant if such a leakage occurs. Furthermore, one objective of the present invention is to find a technical solution which reduces the risk of ignition, if a leakage of refrigerant has occurred or is about to occur.

According to one aspect, the invention concerns a safety system in an air handling system for evacuation of contaminated air and prevention of ignition. The air handling system comprises a compressor enclosure. The safety system is connectable to a power supply and comprises an evacuation unit connected to the compressor enclosure for evacuation of contaminated air from the compressor enclosure according to the appended claims.

An advantage of the solution, is that contaminated air from the compressor enclosure could be evacuated so that the contaminated air does not enter the air treatment area of the air handling unit. Furthermore, contaminated air from the compressor enclosure could be evacuated so that the contaminated air does not ignite due to any electrical component present in the compressor enclosure according to the appended claims.

The evacuation unit comprises a duct unit and an extraction unit.

An advantage of the solution, is that contaminated air from the compressor enclosure could be even more efficiently evacuated so that the contaminated air does not enter the air treatment area of the air handling unit. Furthermore, contaminated air from the compressor enclosure could be even more efficiently evacuated so that the contaminated air does not ignite due to any electrical component present in the compressor enclosure.

According to the invention, the system comprises an air contamination sensor positioned in the compressor enclosure for collection of air contamination data, and an air flow sensor arranged in or in proximity to the evacuation unit for collection of air flow data.

An advantage of the solution, is that the air contamination sensor could collect data with regards to potentially contaminated air in the compressor enclosure. Furthermore, the air flow sensor could collect data with regards to the degree of air flow in the evacuation unit. The lower the air flow, the greater risk for a potential leaking refrigerant to accumulate and result in a flammable gas mixture in the compressor enclosure.

According to the invention, the power supply is divided into a safety system power supply and an air handling power supply. The safety system power supply provides power to the extraction unit, the air contamination sensor and the air flow sensor. The air handling power supply provides power to the air handling system. The safety system power supply and the air handling power supply are operating independently of each other.

An advantage of the solution, by having the safety system power supply and the air handling power supply operating independently of each other, is that the operating mode of the air handling power supply does not impact the operating mode of the safety system power supply. This implies that contaminated air from the compressor enclosure could be evacuated by means of the safety system power supply independently from the operating mode of the air handling power supply, so that the contaminated air does not enter the air treatment area of the air handling unit. Furthermore, contaminated air from the compressor enclosure could be evacuated by means of the safety system power supply independently from the operating mode of the air handling power supply, so that the contaminated air does not ignite due to any electrical component present in the compressor enclosure.

According to an embodiment of the invention, the safety system power supply is continuously operating irrespective of the air handling power supply being active or inactive.

An advantage of the solution, by having the safety system power supply continuously operating irrespective of the air handling power supply being active or inactive, is that a potential inactivity of the air handling power supply does not imply that the safety system power supply turns inactive. This further implies that contaminated air from the compressor enclosure could be evacuated by means of the safety system power supply irrespective of the air handling power supply being active or inactive so that the contaminated air does not enter the air treatment area of the air handling unit. Furthermore, contaminated air from the compressor enclosure could be evacuated by means of the safety system power supply irrespective of the air handling power supply being active or inactive, so that the contaminated air does not ignite due to any electrical component present in the compressor enclosure.

According to an example, the extraction unit is a fan.

An advantage of the solution, is that a fan is standard evacuation component resulting in a robust and cost efficient technical solution.

According to the invention, the system comprises an air contamination sensor positioned in the compressor enclosure for collection of air contamination data.

An advantage of the solution, is that the air contamination sensor could collect data with regards to potentially contaminated air in the compressor enclosure.

According to an embodiment of the invention, the extraction unit may be a first and a second fan connected in series or in parallel.

An advantage of the solution, is that a fan is standard evacuation component resulting in a robust and cost efficient technical solution. Furthermore, having two fans connected in series would increase the robustness of the system. This further implies that contaminated air from the compressor enclosure could be evacuated by means of the second fan irrespective of the first fan being active or inactive so that the contaminated air does not enter the air treatment area of the air handling unit. Furthermore, contaminated air from the compressor enclosure could be evacuated by means of the second fan irrespective of the first fan being active or inactive, so that the contaminated air does not ignite due to any electrical component present in the compressor enclosure.

According to an embodiment of the invention, at least one of the first fan and the second fan may be connected to an uninterruptible power supply for providing power in case of a power cut.

An advantage of the solution, is that it would increase the robustness of the system. This further implies that contaminated air from the compressor enclosure could be evacuated by means of at least a fan being active supplied by power from an uninterruptible power supply if there is a power cut, so that the contaminated air does not enter the air treatment area of the air handling unit. Furthermore, contaminated air from the compressor enclosure could be evacuated by means of at least a fan being active supplied by power from an uninterruptible power supply if there is a power cut, so that the contaminated air does not ignite due to any electrical component present in the compressor enclosure.

According to example, a duct inlet of the duct unit may be arranged in a bottom part of the compressor enclosure.

An advantage of the solution, is that contaminated air from the compressor enclosure could be even more efficiently evacuated so that the contaminated air does not enter the air treatment area of the air handling unit. Furthermore, contaminated air from the compressor enclosure could be even more efficiently evacuated so that the contaminated air does not ignite due to any electrical component present in the compressor enclosure. The underlying reason to the above, is that contaminated air most often will sink to the bottom of the compressor enclosure, and if the duct inlet of the duct unit is arranged in a bottom part of the compressor enclosure the contaminated air will more efficiently be evacuated from the compressor enclosure.

According to an example, an air supply inlet for supply of air may be arranged in an upper part of the compressor enclosure.

An advantage of the solution, is that contaminated air from the compressor enclosure could be even more efficiently evacuated so that the contaminated air does not enter the air treatment area of the air handling unit. Furthermore, contaminated air from the compressor enclosure could be even more efficiently evacuated so that the contaminated air does not ignite due to any electrical component present in the compressor enclosure. The underlying reason to the above, is that contaminated air most often will sink to the bottom of the compressor enclosure, and if the air supply inlet for supply of air is arranged in an upper part of the compressor enclosure there will be a relatively good air flow from the upper part to the bottom part of the compressor enclosure improving the evacuation of contaminated air.

According to an example, the contaminated air may contain flammable gas.

An advantage of the solution, is that flammable gas from the compressor enclosure could be evacuated so that the flammable gas does not enter the air treatment area of the air handling unit. Furthermore, flammable gas from the compressor enclosure could be evacuated so that the flammable gas does not ignite due to any electrical component present in the compressor enclosure.

According to an example, the flammable gas may be of the type R32 or any other A2L classified refrigerant.

According to an example, the flammable gas may be of the type propane or any other A3 classified refrigerant.

According to a second aspect, the invention concerns a method for controlling a safety system for evacuation of contaminated air and prevention of ignition in an air handling system as defined in claim <NUM>;.

Including the steps: providing power to the air handling system and an extraction unit by means of a power supply. Providing power to the extraction unit by means of an uninterruptible power supply as a response to if the power supply stops providing power.

An advantage of the solution, is that it would increase the robustness of the system. This further implies that contaminated air from the compressor enclosure could be evacuated by means of the extraction unit being active supplied by power from an uninterruptible power supply if there is a power cut, so that the contaminated air does not enter the air treatment area of the air handling unit. Furthermore, contaminated air from the compressor enclosure could be evacuated by means of the extraction unit supplied by power from an uninterruptible power supply if there is a power cut, so that the contaminated air does not ignite due to any electrical component present in the compressor enclosure.

According to an example, the extraction unit may be a fan.

According to a preferred embodiment, the extraction unit may be a first and a second fan connected in series or in parallel.

According to a preferred embodiment, the method further comprises the following step. Providing power to the first fan by means of an uninterruptible power supply as a response to if the power supply stops providing power.

According to a preferred embodiment, the method further comprises the following step. Providing power to the second fan by means of the uninterruptible power supply as a response to if the power supply stops providing power.

An advantage of the solution, is that it would increase the robustness of the system even further. This further implies that contaminated air from the compressor enclosure could be evacuated by means of the first and the second fan being active supplied by power from an uninterruptible power supply if there is a power cut, so that the contaminated air does not enter the air treatment area of the air handling unit. Furthermore, contaminated air from the compressor enclosure could be evacuated by means of the first and the second fan being active supplied by power from an uninterruptible power supply if there is a power cut, so that the contaminated air does not ignite due to any electrical component present in the compressor enclosure.

According to a preferred embodiment, the method further comprises the following steps. Providing power to an air contamination sensor by means of the power supply. Collecting air contamination data by means of the air contamination sensor. Comparing the collected air contamination data to a predefined air contamination threshold value. Transmitting an alarm to an operator as a response to if an air contamination data value of the collected air contamination data is greater than the predefined air contamination threshold value.

An advantage of the solution, is that an operator after having received an alarm could control the air handling unit for any potential leaking refrigerant in the compressor enclosure, and subsequently having the leaking component being replaced or repaired.

According to a third aspect, the invention concerns a method for controlling a safety system for evacuation of contaminated air and prevention of ignition in an air handling system which has been preceded by the following steps. Providing power to the air handling system by means of an air handling power supply. Providing power to an air flow sensor, an air contamination sensor and an extraction unit by means of a safety system power supply. The method for controlling a safety system comprises the following steps. Collecting air contamination data by means of an air contamination sensor. Comparing the collected air contamination data to a predefined air contamination threshold value. Shutting down the air handling power supply providing power to the air handling system as a response to if an air contamination data value of the collected air contamination data is greater than the predefined air contamination threshold value according to the appended claims.

An advantage of the solution, is that contaminated air from the compressor enclosure would not ignite due to any active electrical component present in the compressor enclosure.

According to a preferred embodiment, the method further comprises the following steps. Collecting air flow data by means of an air flow sensor. Comparing the collected air flow data to a predefined air flow threshold value. Shutting down the air handling power supply providing power to the air handling system as a response to if an air flow data value of the collected air flow data is lower than the predefined air flow threshold value.

An advantage of the solution, is that contaminated air from the compressor enclosure would not ignite due to any active electrical component present in the compressor enclosure and powered by the air handling power supply. The underlying reason to shut down the air handling power supply providing power to the air handling system, is that if the amount of air flow in the evacuation unit is determined to not be enough, a potential leak of contaminated air could lead to an ignition in the compressor enclosure.

According to a preferred embodiment, the method has been preceded by the following step. Shutting down the air handling power supply providing power to the air handling system as a response to that an air flow data value of the collected air flow data has been lower than the predefined air flow threshold value. The method further comprises the following step. Restarting the air handling power supply providing power to the air handling system as a response to that an air flow data value of the collected air flow data is greater than the predefined air flow threshold value.

An advantage of the solution, is that contaminated air from the compressor enclosure would not ignite due to any active electrical component present in the compressor enclosure and powered by the air handling power supply when the air flow is determined to not be enough. The underlying reason to initially shut down the air handling power supply providing power to the air handling system, is that if the amount of air flow in the evacuation unit is not enough, a potential leak of contaminated air could lead to an ignition in the compressor enclosure. The underlying reason to restart the air handling system is to provide cooled/heated air once again.

According to a fourth aspect of the invention a computer readable medium storing a computer program product is accomplished.

A computer program product is provided comprising coded instructions to implement a method when the computer program product is executed in a processor provided in the system.

A computer readable medium storing a computer program product is provided.

The technology described is in particular suitable for integrated reversible heat pumps.

A3 and A2L are different safety group classifications of refrigerants according to the ANSI/ASHRAE Standard <NUM>-<NUM>. Designation and Safety Classification of Refrigerants.

Refrigerant is a term equivalent to the medium which circulates in a refrigerant circuit and which in heating mode picks up heat at a low temperature in the evaporator and subsequently releases the heat at a higher temperature and a higher pressure in the condenser. The refrigerant can take up and release more energy at the transition between different states (gas or liquid) than than only a change in temperatures.

For heating mode the direct DX coil in the exhaust air is the equivalent as the evaporator in the heat pump circuit. The very same direct DX coil constitutes the condenser in cooling mode.

The evacuation unit may also be used as ventilation to avoid high temperatures in the compressor enclosure.

If a leakage occurs in the refrigerant circuit, the air contamination sensor will detect the concentration of the refrigerant, for instance R32 in air less or equal to <NUM>% of LFL and shut down the power to the air handling unit. Electrical power will then only be supplied to the evacuation unit and the sensor. With gas concentrations far below the LFL, an alarm will initially be transmitted informing an operator that a leakage is present.

Lower Flammable Limit (LFL) in kg/m3. LFL for R32 equals <NUM>/m3.

One fan would be enough to ventilate the compressor enclosure to avoid flammable concentrations, which for instance could be <NUM>% under LFL.

The air handling system could be offered in two different options. The first option is a system with a compressor enclosure designed for indoor use. The second option is a system with a compressor enclosure designed for outdoor use. If the compressor enclose is placed outside there would be no need for installation of additional duct units. Additional duct units must only be installed if the machine room volume is not enough or if the machine room is not ventilated.

The collected air contamination data could instead be air quality data, where if the collected air quality data value is low enough this would imply that there is an air contamination present in the atmosphere and the system would thus react.

The evacuation unit could be arranged at an outlet of the duct unit, in the duct unit, or at an inlet of the duct unit. If the evacuation unit are two fans, each specific fan could individually be arranged at an outlet of the duct unit, in the duct unit, or at an inlet of the duct unit.

The contaminated air is by means of the evacuation unit evacuated to outside the air handling unit and outside any premises so that human beings will not be affected by the contaminated air. In case of the contaminated air being a flammable refrigerant, the risk of ignition of the refrigerant is greatly reduced by evacuating the refrigerant to outside the air handling unit and outside any premises.

In the compressor enclosure there are often a lot of different electric and electronic components present. Power to these components should be shut down if there is contaminated air present in the compressor enclosure.

The duct inlet of the duct unit could either be arranged in a bottom part of the compressor enclosure or connected to a bottom part of the compressor enclosure.

The air flow sensor which is arranged in or in proximity to the evacuation unit for collection of air flow data collects data with regards to the degree of air flow in the evacuation unit. In proximity means that the sensor is arranged in such a manner that the air flow in, to, or from the evacuation unit can be measured.

In the following, a detailed description of an air handling system for heating/cooling of air is provided.

<FIG>, <FIG>, <FIG>, <FIG>, <FIG> and <FIG> shows a safety system <NUM> for evacuation of contaminated air and prevention of ignition in an air handling system <NUM> according to different embodiments of the invention.

<FIG> and <FIG> shows a safety system <NUM> for evacuation of contaminated air and prevention of ignition in an air handling system <NUM> according to an embodiment of the invention. The air handling system <NUM> made up of a compressor enclosure <NUM>. The safety system <NUM> is connectable to a power supply <NUM> and comprises an evacuation unit <NUM> connected to the compressor enclosure <NUM> for evacuation of contaminated air from the compressor enclosure <NUM>. The evacuation unit <NUM> comprises a duct unit <NUM> and an extraction unit <NUM>. An air contamination sensor <NUM> is positioned in the compressor enclosure <NUM> for collection of air contamination data <NUM>. An air flow sensor <NUM> is arranged in or in proximity to the evacuation unit <NUM> for collection of air flow data <NUM>.

<FIG> and <FIG> shows a safety system <NUM> for evacuation of contaminated air and prevention of ignition in an air handling system <NUM> according to an embodiment of the invention. The air handling system <NUM> made up of a compressor enclosure <NUM>. The safety system <NUM> is connectable to a power supply <NUM> and comprises two evacuation units <NUM> connected in parallel to the compressor enclosure <NUM> for evacuation of contaminated air from the compressor enclosure <NUM>. An evacuation unit <NUM> comprises a duct unit <NUM> and an extraction unit <NUM>. The extraction unit <NUM> is a first <NUM> and a second fan <NUM> connected in parallel. At least one of the first fan <NUM> and the second fan <NUM> is connected to an uninterruptible power supply <NUM> for providing power in case of a power cut. An air contamination sensor <NUM> is positioned in the compressor enclosure <NUM> for collection of air contamination data <NUM>.

<FIG> and <FIG> shows a safety system <NUM> for evacuation of contaminated air and prevention of ignition in an air handling system <NUM> according to an embodiment of the invention. The air handling system <NUM> made up of a compressor enclosure <NUM>. The safety system <NUM> is connectable to a power supply <NUM> and comprises an evacuation unit <NUM> connected to the compressor enclosure <NUM> for evacuation of contaminated air from the compressor enclosure <NUM>. The evacuation unit <NUM> comprises a duct unit <NUM> and an extraction unit <NUM>. The extraction unit <NUM> is a first <NUM> and a second fan <NUM> connected in series. An air contamination sensor <NUM> is positioned in the compressor enclosure <NUM> for collection of air contamination data <NUM>. At least one of the first fan <NUM> and the second fan <NUM> is connected to an uninterruptible power supply <NUM> for providing power in case of a power cut.

The air to be treated passes through the evaporator/condenser coil in the air treatment space <NUM>. The treated air is to be transferred to the premises where e.g. human beings are to be found. In the air treatment space <NUM> or in said premises there should be no leaking refrigerant <NUM>.

In a step S100 power is provided to the air handling system <NUM> and an extraction unit <NUM> by means of a power supply <NUM>. In a step S110 power is provided to the extraction unit <NUM> by means of an uninterruptible power supply <NUM> as a response to if the power supply <NUM> stops providing power.

The method for controlling a safety system <NUM> is preceded by the steps S200-S210. In a step S200 power is provided to the air handling system <NUM> by means of an air handling power supply <NUM>. In a step S210 power is provided to an air flow sensor <NUM>, an air contamination sensor <NUM> and an extraction unit <NUM> by means of a safety system power supply <NUM>. The method for controlling a safety system <NUM> comprises the steps of S220-S240. In a step S220 air contamination data <NUM> is collected by means of an air contamination sensor <NUM>. In a step S230 the collected air contamination data <NUM> is compared to a predefined air contamination threshold value <NUM>. In a step S240 the air handling power supply <NUM> which is providing power to the air handling system <NUM> is shut down as a response to if an air contamination data value <NUM> of the collected air contamination data <NUM> is greater than the predefined air contamination threshold value <NUM>.

Claim 1:
An air handling system (<NUM>) comprising a safety system (<NUM>) for evacuation of contaminated air and prevention of ignition,
wherein the air handling system (<NUM>) comprises a compressor enclosure (<NUM>),
wherein the safety system (<NUM>) is connectable to a power supply (<NUM>) and comprises
an evacuation unit (<NUM>) connected to the compressor enclosure (<NUM>) for evacuation of contaminated air from the compressor enclosure (<NUM>), and
wherein said safety system comprises an air contamination sensor (<NUM>) positioned in the compressor enclosure (<NUM>) for collection of air contamination data (<NUM>, <NUM>), characterized in that the safety system further comprises an air flow sensor (<NUM>) arranged in or in proximity to the evacuation unit (<NUM>) for collection of air flow data (<NUM>), wherein the evacuation unit (<NUM>) comprises a duct unit (<NUM>) and an extraction unit (<NUM>), and in that the power supply (<NUM>) is divided into a safety system power supply (<NUM>) and an air handling power supply (<NUM>), wherein the safety system power supply (<NUM>) provides power to the extraction unit (<NUM>), the air contamination sensor (<NUM>) and the air flow sensor (<NUM>), and wherein the air handling power supply (<NUM>) provides power to the air handling system (<NUM>), wherein the safety system power supply (<NUM>) and the air handling power supply (<NUM>) are operating independently of each other.