According to a third 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 cooling, heating and reversible heat pumps.

A3 and A2L are different safety group classifications of refrigerants according to the ANSI/ASHRAE Standard 34-2007. 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 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.

The Lower Flammable Limit (LFL) is the lower end of the concentration range of a flammable gas, which can ignite with air at normal temperature and pressure. Below LFL, the vapour/air mixture will not ignite. The LFL may be measured in kg/m3. The LFL for R32 equals 0.306 kg/m3.

One fan may be enough to ventilate the compressor enclosure to avoid flammable concentrations.

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 compressor enclosure extract air unit could be arranged at an outlet of the compressor enclosure duct unit, in the duct unit, or at an inlet of the duct unit. If the compressor enclosure extract air unit comprises 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, in some embodiments, 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 may be shut down if there is contaminated air present.

An air flow sensor which may be arranged in the air handling system for collection of air flow data collects data with regards to the degree of air flow in the system. The sensor is arranged in such a manner that the air flow in, to, or from the air handling system can be measured.

At least one of the supply air unit, the exhaust air unit and the compressor enclosure extract air unit may be a fan.

Starting the supply air unit, the exhaust air unit and the compressor enclosure extract air unit at least at 5% of the nominal air flow of the system, which corresponds to an air flow velocity of 1.5-2.5 m/s in the system. In addition to this, the air flow of the system should be at least 0.1 m3/s.

If the collected air contamination data does stay over the predefined air contamination data threshold value, then the air flow of the system should be increased in steps of 0.1 m3/s until the maximum air flow of the system is reached. The time interval for each step should be between 1 second and 60 seconds.

The predefined time may preferably be 0.5-3 hours, more preferably 0.75-2 hours and most preferably 1-1.5 hours.

The wording ambient mentioned in the claims may be equivalent to the outdoors or the surrounding air external to the system, among others.

The outdoor air valve may function as an air valve for the supply of supply air into the supply air duct from the ambient, wherein the ambient may be the outdoors or be the ambient within an industrial premises.

Method according to claim 1, wherein the method further comprises after step B the step of triggering an alarm to be presented locally on e.g. the user interface of the control unit. Wherein the alarm may also be sent to a central control unit of the building. The central control unit of the building may sometimes be referred to as a Building Management System (BMS).

It may be an advantage to have a separate enclosure for the control unit of the system.

The contamination sensors of the system are continuously active in order to be able to react to any leakage at any given time, and are powered by means of the power supply.

BRIEF DESCRIPTION OF DRAWINGS

The invention is now described, by way of example, with reference to the accompanying drawings, in which:

FIGS. 1, 3, 4, 5 and 6a show a safety system for evacuation of contaminated air and prevention of ignition in an air handling system, in a front view, according to an embodiment of the invention, and

FIGS. 2, 6b and 6c shows a safety system for evacuation of contaminated air and prevention of ignition in an air handling system, from above, according to an embodiment of the invention, and

FIG. 7 shows a flow chart of a method according to an embodiment of the invention, and

FIG. 8 shows a flow chart of a method according to an embodiment of the invention, and

FIG. 9 shows a flow chart of a method according to an embodiment of the invention, and

FIG. 10 shows a block diagram of a control system according to an embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

In the following, a detailed description of a safety system for evacuation of contaminated air and prevention of ignition in an air handling system is provided.

FIG. 1 shows a safety system 1 for evacuation of contaminated air and prevention of ignition in an air handling system 2, according to an embodiment of the invention. The air handling system 2 is made up of a compressor 36 for compressing a refrigerant 37 for further being led through an evaporator/condenser coil 38 arranged in the air handling system 2, a supply air unit 3 arranged in a supply air duct 4, and an exhaust air unit 5 arranged in an exhaust air duct 6. The safety system 1 is made up of a supply air contamination sensor 7 arranged in the supply air duct 4, an exhaust air contamination sensor 8 arranged in the exhaust air duct. The supply air contamination sensor 7 and the exhaust air contamination sensor 8 collect air contamination data. The air handling system 2 is further made up of a control unit 10 for comparison of collected air contamination data 9 to a predefined air contamination data threshold value 11, and for controlling the supply air unit 3, and the exhaust air unit 5. The air handling system 2 is further made up of a power supply 12 for providing power to the supply air unit 3, the exhaust air unit 5 and the control unit 10. The compressor 36 is arranged within the exhaust air duct 6.

FIG. 2 shows a safety system 1 for evacuation of contaminated air and prevention of ignition in an air handling system 2, according to an embodiment of the invention. The compressor 36 is arranged within the exhaust air duct 6. The system is further made up of an extract air valve 15, variable between a closed and an open position, arranged in an extract air inlet end 16 of the exhaust air duct 6 for the extraction of used extract air A_Efrom the room 35 into the exhaust air duct 6. The system is further made up of an exhaust air valve 20, variable between a closed and an open position, arranged in an exhaust air outlet end 21 of the exhaust air duct 6 for the exhaust of used extract air A_Efrom the exhaust air duct 6 to the ambient. The extract air valve 15 and the exhaust air valve 20 are controlled by the control unit 10.

FIG. 3 shows a safety system 1 for evacuation of contaminated air and prevention of ignition in an air handling system 2, according to an embodiment of the invention. The air handling system 2 is made up of a compressor 36 for compressing a refrigerant 37 for further being led through an evaporator/condenser coil 38 arranged in the air handling system 2, a supply air unit 3 arranged in a supply air duct 4, and an exhaust air unit 5 arranged in an exhaust air duct 6. The safety system 1 is made up of a supply air contamination sensor 7 arranged in the supply air duct 4, an exhaust air contamination sensor 8 arranged in the exhaust air duct. The supply air contamination sensor 7 and the exhaust air contamination sensor 8 collect air contamination data. The air handling system 2 is further made up of a control unit 10 for comparison of collected air contamination data 9 to a predefined air contamination data threshold value 11, and for controlling the supply air unit 3, and the exhaust air unit 5. The air handling system 2 is further made up of a power supply 12 for providing power to the supply air unit 3, the exhaust air unit 5 and the control unit 10. The compressor 36 is arranged within a compressor enclosure 22 (not shown) separate from the supply air duct 4 and the exhaust air duct 6. A compressor enclosure contamination sensor 23 is arranged in the compressor enclosure 22 for collection of air contamination data 9.

FIG. 4 shows a safety system 1 for evacuation of contaminated air and prevention of ignition in an air handling system 2, according to an embodiment of the invention.

The air handling system 2 is made up of a compressor 36 for compressing a refrigerant 37 for further being led through an evaporator/condenser coil 38 arranged in the air handling system 2, a supply air unit 3 arranged in a supply air duct 4, and an exhaust air unit 5 arranged in an exhaust air duct 6. The safety system 1 is made up of a supply air contamination sensor 7 arranged in the supply air duct 4, an exhaust air contamination sensor 8 arranged in the exhaust air duct. The supply air contamination sensor 7 and the exhaust air contamination sensor 8 collect air contamination data. The air handling system 2 is further made up of a control unit 10 for comparison of collected air contamination data 9 to a predefined air contamination data threshold value 11, and for controlling the supply air unit 3, and the exhaust air unit 5. The air handling system 2 is further made up of a power supply 12 for providing power to the supply air unit 3, the exhaust air unit 5 and the control unit 10. The safety system 1 is further made up of a supply air valve 13, variable between a closed and an open position, arranged in a supply air outlet end 14 of the supply air duct 4 for the supply of supply air A_Sto a room 35, an extract air valve 15, variable between a closed and an open position, arranged in an extract air inlet end 16 of the exhaust air duct 6 for the extraction of used extract air A_Efrom the room 35 into the exhaust air duct 6, and a by-pass valve 17, variable between a closed and an open position, arranged to connect the supply air duct 4 and the exhaust air duct 6 for the fluid connection of supply air A_Sin the event that the supply air valve 13 and the extract air valve 15 are closed. The supply air valve 13, the extract air valve 15 and the by-pass valve 17 are controlled by the control unit 10. The compressor 36 is arranged within a compressor enclosure 22 (not shown) separate from the supply air duct 4 and the exhaust air duct 6. A compressor enclosure contamination sensor 23 is arranged in the compressor enclosure 22 for collection of air contamination data 9.

FIG. 5 shows a safety system 1 for evacuation of contaminated air and prevention of ignition in an air handling system 2, according to an embodiment of the invention. The air handling system 2 is made up of a compressor 36 for compressing a refrigerant 37 for further being led through an evaporator/condenser coil 38 arranged in the air handling system 2, a supply air unit 3 arranged in a supply air duct 4, and an exhaust air unit 5 arranged in an exhaust air duct 6. The safety system 1 is made up of a supply air contamination sensor 7 arranged in the supply air duct 4, an exhaust air contamination sensor 8 arranged in the exhaust air duct. The supply air contamination sensor 7 and the exhaust air contamination sensor 8 collect air contamination data. The air handling system 2 is further made up of a control unit 10 for comparison of collected air contamination data 9 to a predefined air contamination data threshold value 11, and for controlling the supply air unit 3, and the exhaust air unit 5. The air handling system 2 is further made up of a power supply 12 for providing power to the supply air unit 3, the exhaust air unit 5 and the control unit 10. The safety system 1 is further made up of a supply air valve 13, variable between a closed and an open position, arranged in a supply air outlet end 14 of the supply air duct 4 for the supply of supply air A_Sto a room 35, an extract air valve 15, variable between a closed and an open position, arranged in an extract air inlet end