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Title:
METHOD AND SYSTEM FOR CLEANING A HEAT EXCHANGER
Document Type and Number:
WIPO Patent Application WO/2019/045620
Kind Code:
A1
Abstract:
The present invention relates to a method for cleaning a heat exchanger (10). Said heat exchanger (10) comprises an inlet (12) which, during intended heating operation of the heat exchanger (10), is configured to receive a fluid, a plurality of channels (16) through which said fluid is arranged to flow for heating air passing between said channels (16) during said intended heating operation, and an outlet (14) for letting out the thus received fluid. The method comprises the steps of, during a cleaning operation, attaching a supply pipe (21) to said inlet (12) or outlet (14) for providing hot fluid to said heat exchanger (10); providing hot fluid through said supply pipe (21); and supplying pressurized air in pulses to said supply pipe (21) so as to provide said hot fluid to an increased flow rate through said plurality of channels (16) for cleaning said channels (16). The present invention also relates to an arrangement for cleaning a heat exchanger. The present invention also relates to a vehicle.

Inventors:
DUNBERGER, Lars (Sibyllegatan 52A, Stockholm, 114 43, SE)
KALLIO, Mikko (Nyhemsvägen 11, Hölö, 153 71, SE)
LINDQVIST, Magnus (Sandviksvägen 10, Enhörna, 151 96, SE)
Application Number:
SE2018/050852
Publication Date:
March 07, 2019
Filing Date:
August 24, 2018
Export Citation:
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Assignee:
SCANIA CV AB (151 87 Södertälje, 151 87, SE)
International Classes:
F28G7/00; F01P11/06; F28G9/00
Foreign References:
US2604895A1952-07-29
US2638381A1953-05-12
US4492113A1985-01-08
US1939836A1933-12-19
KR20140102814A2014-08-25
US20030051746A12003-03-20
US3034521A1962-05-15
US2839068A1958-06-17
Attorney, Agent or Firm:
AHLING, Annika (Scania CV AB, Södertälje, 151 87, SE)
Download PDF:
Claims:
CLAIMS

1 . A method for cleaning a heat exchanger (10), said heat exchanger (10) comprising an inlet (12) which, during intended heating operation of the heat exchanger (10), is configured to receive a fluid, a plurality of channels (18) through which said fluid is arranged to flow for heating air passing between said channels (18) during said intended heating operation, and an outlet (14) for letting out the thus received fluid, characterized by the steps of, during a cleaning operation,

- attaching (S1 ) a supply pipe (21 ) to said inlet (12) or outlet (14) for providing hot fluid to said heat exchanger (10);

- providing (S2) hot fluid through said supply pipe (21 ); and

- supplying (S3) pressurized air in pulses to said supply pipe (21 ) so as to provide said hot fluid to an increased flow rate through said plurality of channels (16) for cleaning said channels (16). 2. A method according to claim 1 , wherein said pressurized air pulse flow is provided based on amount of fluid to be provided to said heat exchanger (10) and/or length (L) of supply pipe (21 a) from pressurized air supply (21 i) to heat exchanger and/or cross sectional area (A) of supply pipe (21 ).

3. A method according to claim 1 or 2, further comprising the step of preventing said hot fluid from being pushed back through said supply pipe (21 ) by means of a check valve (24) arranged upstream of said pressurized air supply (21 i).

4. A method according to any of claims 1 -3, further comprising the step of preventing said flow of hot fluid through said heat exchanger (10) by means of a safety valve (25) arranged downstream of said pressurized air supply (21 i) if the pressure of said hot fluid flow exceeds a predetermined pressure.

5. A method according to any of claims 1 -4, wherein said fluid is water.

6. A method according to any of claims 1 -3, further comprising the step of, in connection to attaching said supply pipe (21 ), attaching an exhaust pipe (27) to the other of said outlet (14) or inlet (12) for exhausting said fluid having passed through said plurality of channels (18). 7. An arrangement (20) for cleaning a heat exchanger (10), said heat exchanger (10) comprising an inlet (12) which, during intended heating operation of the heat exchanger (10), is configured to receive a fluid, a plurality of channels (16) through which said fluid is arranged to flow for heating air passing between said channels (16) during said intended heating operation, and an outlet (14) for letting out the thus received fluid, characterized in that the arrangement (20) comprises a supply pipe (21 ) configured to, during a cleaning operation, be attached to said inlet (12) or outlet (14) for providing hot fluid to said heat exchanger (10); means (22) for providing hot fluid through said supply pipe (21 ); and means (23) for supplying pressurized air in pulses to said supply pipe (21 ) so as to provide said hot fluid to an increased flow rate through said plurality of channels (16) for cleaning said channels (16).

8. An arrangement according to claim 7, wherein said pressurized air pulse flow is arranged to be provided based on amount of fluid to be provided to said heat exchanger (10) and/or length (L) of supply pipe (21 a) from pressurized air supply (21 i) to heat exchanger (10) and/or cross sectional area (A) of supply pipe (21 ).

9. An arrangement according to claim 7 or 8, further comprising a check valve (24) arranged upstream of said pressurized air supply (21 i), said check valve (24) being configured to prevent said hot fluid from being pushed back through said supply pipe (21 ).

10. An arrangement according to any of claims 7-9, further comprising a safety valve (25) arranged downstream of said pressurized air supply (21 1), said safety valve (25) being configured to prevent said flow of hot fluid through said heat exchanger (10) if the pressure of said hot fluid flow exceeds a predetermined pressure.

1 1 . An arrangement according to any of claims 7-10, wherein said fluid is water. 12. An arrangement according to any of claims 7-1 1 , further comprising an exhaust pipe (27) configured to be attached to the other of said outlet (14) or inlet (12) for exhausting said fluid having passed through said plurality of channels (16).

13. A vehicle (V) comprising an arrangement (I) according to any of claims 7- 12.

Description:
METHOD AND SYSTEM FOR CLEANING A HEAT EXCHANGER

TECHNICAL FIELD

The invention relates to a method for cleaning a heat exchanger. The invention also relates to an arrangement for cleaning a heat exchanger. The invention also relates to a vehicle.

BACKGROUND ART

Heat exchangers comprising an inlet which is configured to receive a heated coolant, i.e. a fluid such as water, a plurality of channels through which said fluid is arranged to flow for heating air passing between said channels during said intended heating operation, and an outlet for exhausting said fluid may advantageously be used in e.g. vehicles such as trucks for heating the interior of the vehicle. The coolant is configured to be heated by e.g. the vehicle engine and pumped to said inlet for heating the air. Fin plates are arranged between the channels for transferring said air passing between said channels. Such heat exchangers may be denoted fin-plate heat exchangers.

During operation of such a heat exchanger arranged in a vehicle the coolant can transfer particles and impurities which can block the narrow channels of the heat exchanger. The impurities in the coolant system can comprise different materials and vary in size. The channels may be clogged by these impurities due to e.g. galvanic reasons. Hereby the coolant cannot flow through the blocked channels resulting in decreased heat transfer between the coolant and the air and thus a less efficient/malfunctioning heat exchanger. A common solution to this problem is to replace the heat exchanger which is time consuming and costly. Unsuccessful attempts have been made to clean such a heat exchanger. There is thus a need for improving cleaning of such a heat exchanger,

OBJECTS OF THE INVENTION

An object of the present invention is to provide a method for cleaning a heat exchanger which is easy and efficient.

Another object of the present invention is to provide an arrangement for cleaning a heat exchanger which is easy and efficient.

SUMMARY OF THE INVENTION These and other objects, apparent from the following description, are achieved by a method, an arrangement and a vehicle, as set out in the appended independent claims. Preferred embodiments of the method and the arrangement are defined in appended dependent claims.

Specifically an object of the invention is achieved by a method for cleaning a heat exchanger. Said heat exchanger comprises an inlet which, during intended heating operation of the heat exchanger, is configured to receive a fluid, a plurality of channels through which said fluid is arranged to flow for heating air passing between said channels during said intended heating operation, and an outlet for letting out the thus received fluid. The method comprises the steps of, during a cleaning operation, attaching a supply pipe to said inlet or outlet for providing hot fluid to said heat exchanger; providing hot fluid through said supply pipe; and supplying pressurized air in pulses to said supply pipe so as to provide said hot fluid to an increased flow rate through said plurality of channels for cleaning said channels. By thus during said cleaning operation providing hot fluid through said supply pipe and supplying pressurized air in pulses to said supply pipe so as to provide said hot fluid to an increased flow rate through said plurality of channels for cleaning said channels an efficient and easy way of cleaning said channels is facilitated. This is due to the higher flow rate in combination with the controlled air pulses accelerating the hot fluid, e.g. water, through the narrow channels. The pressurized air provided in pulses may hereby be adapted such that an increased flow rate of said hot fluid is obtained without mixing the fluid, e.g. water, with air to any significant extent. For such a heat exchanger being arranged in a vehicle, e.g. a cab of a truck, the heat exchanger does not need to be removed from the cab, only connections to inlet and outlet need to be detached. Hereby cleaning may be efficiently performed in a workshop utilizing municipal hot water as fluid and pressurized air available in the workshop. Cleaning may be required only during a few minutes in order to have a good result of said cleaning of said heat exchanger.

The hot fluid is thus accelerated to said increased flow rate by means of said pressurized air in pulses. Flow rate of said hot fluid refers to flow velocity.

Thus, the step of supplying pressurized air in pulses to said supply pipe so as to provide said hot fluid to an increased flow rate through said plurality of channels for cleaning said channels comprises adapting the pulses and air pressure to optimize acceleration of said hot fluid to an increased flow rate without mixing the fluid, e.g. water, with air to any significant extent. Mixing of air and said hot fluid is preferably avoided to the extent possible. According to an embodiment said pulses of pressurized air are provided with a frequency of about 1 Hz, i.e. 0.5 seconds on and 0.5 seconds off. Said pulses of pressurized air may be provided with any suitable interval and may according to an embodiment be different on time, i.e. time during which pressurized air is provided to the supply pipe, compared to the off time, i.e. time during which said pressurized air is prevented from be provided to said supply pipe, e.g. a longer on time than off time.

Prior to attaching said supply pipe to said inlet or outlet the connection to said inlet/outlet for the intended operation of the heat exchanger is detached. According to an embodiment of the method said supply pipe is attached to said inlet wherein said hot fluid is provided through said supply pipe and accelerated by means of said pressurized air in pulses through said plurality of channels to said outlet for cleaning said channels and thereafter or prior to that said supply pipe is attached to said outlet wherein said hot fluid is provided through said supply pipe and accelerated by means of said pressurized air in pulses the opposite way through said plurality of channels to said inlet for cleaning said channels.

Said air pressure of said pressurized air is adapted to the heat exchanger, i.e. the dimensions of the heat exchanger comprising the dimensions of the plurality of channels of the heat exchanger and the dimensions of the supply pipe. Said air pressure of said pressurized air is according to an embodiment in the range of about 2-5 bar, according to an embodiment in the range of 3-4 bar, which may be suitable for a heat exchanger where said plurality of channels have a relatively small cross section, having e.g. a diameter of about a millimetre or millimetres.

According to an embodiment of the method said pressurized air pulse flow is provided based on amount of fluid to be provided to said heat exchanger and/or length of supply pipe from pressurized air supply to heat exchanger and/or cross sectional area of supply pipe. By thus providing said pressurized air pulse flow optimization of acceleration of said hot fluid to an increased flow rate without mixing the fluid, e.g. water, with air to any significant extent is facilitated. The length of said supply pipe may be in the range of a metre or a few meters. Said supply pipe may have any suitable cross sectional area. Said supply pipe has according to an embodiment a cross sectional area in the range of 1 -15 cm 2 , according to an embodiment about 3-4 cm 2 .

According to an embodiment the method further comprises the step of preventing said hot fluid from being pushed back through said supply pipe by means of a check valve arranged upstream of said pressurized air supply. Hereby avoidance of said hot fluid being pushed back through said supply pipe is facilitated in an easy and efficient way, thus providing an efficient cleaning during cleaning operation.

According to an embodiment the method further comprises the step of preventing said flow of hot fluid through said heat exchanger by means of a safety valve arranged downstream of said pressurized air supply if the pressure of said hot fluid flow exceeds a predetermined pressure.

According to an embodiment of the method said fluid is water. By thus using water for said cleaning operation hot water from the municipal water pipelines may advantageously be used. According to an embodiment the method further comprises the step of, in connection to attaching said supply pipe, attaching an exhaust pipe to the other of said outlet or inlet for exhausting said fluid having passed through said plurality of channels. Hereby the hot fluid may be exhausted in a controlled way. Prior to attaching said exhaust pipe to said inlet or outlet the connection to said inlet/outlet for the intended operation of the heat exchanger is detached.

Specifically an object of the invention is achieved by an arrangement for cleaning a heat exchanger. Said heat exchanger comprises an inlet which, during intended heating operation of the heat exchanger, is configured to receive a fluid, a plurality of channels through which said fluid is arranged to flow for heating air passing between said channels during said intended heating operation, and an outlet for letting out the thus received fluid. Said arrangement comprises a supply pipe configured to, during a cleaning operation, be attached to said inlet or outlet for providing hot fluid to said heat exchanger; means for providing hot fluid through said supply pipe; and means for supplying pressurized air in pulses to said supply pipe so as to provide said hot fluid to an increased flow rate through said plurality of channels for cleaning said channels. According to an embodiment of the arrangement said pressurized air pulse flow is arranged to be provided based on amount of fluid to be provided to said heat exchanger and/or length of supply pipe from pressurized air supply to heat exchanger and/or cross sectional area of supply pipe. According to an embodiment the arrangement further comprises a check valve arranged upstream of said pressurized air supply, said check valve being configured to prevent said hot fluid from being pushed back through said supply pipe.

According to an embodiment the arrangement further comprises a safety valve arranged downstream of said pressurized air supply, said safety valve being configured to prevent said flow of hot fluid through said heat exchanger if the pressure of said hot fluid flow exceeds a predetermined pressure.

According to an embodiment of the arrangement said fluid is water.

According to an embodiment the arrangement further comprises an exhaust pipe configured to be attached to the other of said inlet or outlet for exhausting said fluid having passed through said plurality of channels.

The arrangement for cleaning a heat exchanger is adapted to perform the method as set out herein.

The system according to the invention has the advantages according to the corresponding arrangement.

Specifically an object of the invention is achieved by a vehicle comprising an arrangement as set out herein.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention reference is made to the following detailed description when read in conjunction with the accompanying drawings, wherein like reference characters refer to like parts throughout the several views, and in which:

Fig. 1 schematically illustrates a side view of a vehicle according to the present invention; Fig. 2 schematically illustrates an embodiment of a heat exchanger configured to be cleaned by means of an arrangement for cleaning a heat exchanger according to the present invention;

Fig. 3a schematically illustrates an arrangement for cleaning a heat exchanger according to an embodiment of the present invention; Fig, 3b schematically illustrates a cross sectional view of a supply pipe of the arrangement in fig. 3a; and

Fig. 4 schematically illustrates a system for cleaning a heat exchanger according to an embodiment of the present invention.

DETAILED DESCRIPTION

Fig. 1 schematically illustrates a side view of a vehicle V according to the present invention. The exemplified vehicle V is a commercial vehicle in the shape of a truck. The vehicle according to the present invention could be any suitable vehicle such as a bus or a car. The vehicle V comprises a cab C.

The vehicle V comprises a heat exchanger 10 arranged in connection to the cab C of the vehicle V. The heat exchanger 10 comprises an inlet 12 which, during intended operation, is configured to receive a heated coolant, i.e. a fluid such as water. Said fluid is, during said intended operation, according to an embodiment configured to be heated and pumped by the vehicle engine to said inlet 12 via a pipe connected to said inlet 12. The heat exchanger 10 comprises a plurality of channels, not shown, through which said fluid is arranged to flow for heating air passing between said channels during said intended heating operation, and an outlet 14 for exhausting said fluid.

During a cleaning operation said vehicle is arranged to be provided with an arrangement 20 for cleaning said heat exchanger 10 according to the present invention. In fig. 1 the heat exchanger 10 is configured to be cleaned by means of said arrangement 10 for cleaning a heat exchanger. The vehicle thus comprises said arrangement 20 during cleaning operation of said vehicle. The cleaning operation may advantageously be performed in a workshop by means of said arrangement 20 without disconnected the heat exchanger 10.

During a cleaning operation of said heat exchanger 10 the connection for said heated coolant is detached from the inlet 12 and a supply pipe is configured to be attached to the inlet 12. A hot fluid, preferably water e.g. from the municipal water pipelines, is provided through said supply pipe, wherein pressurized air in pulses is arranged to be provided to said supply pipe so as to accelerate said hot fluid to an increased flow rate through said plurality of channels for cleaning said channels.

Fig. 2 schematically illustrates an embodiment of a heat exchanger 10 configured to be cleaned by means of an arrangement for cleaning a heat exchanger according to the present invention.

The heat exchanger 10 comprises an inlet 12 which, during intended operation, is configured to receive a heated coolant, i.e. a fluid such as water. Said fluid is, during said intended operation, according to an embodiment configured to be heated and pumped by the vehicle engine to said inlet 12 via a pipe connected to said inlet 12. The heat exchanger 10 comprises a plurality of channels 16 through which said fluid is arranged to flow for heating air passing between said channels 16 during said intended heating operation, and an outlet 14 for exhausting said fluid. Fin plates, not shown, are arranged between the channels for transferring said air passing between said channels. Said plurality of channels 16 have a relatively small cross section, having e.g. a diameter of about a millimetre or millimetres.

Said plurality of channels 16 are according to an embodiment arranged essentially parallel. Said heat exchanger comprises a first fluid transport member 17 fluidly connected to said inlet 12 and a second fluid transport member 18 fluidly connected to said outlet 18. Said fluid transport members 17, 18 have a substantially larger cross section than said plurality of channels 16.

Said plurality of channels 16 are according to an embodiment fluidly connected between said first fluid transport member 17 and said second fluid transport member 18.

During intended operation coolant is arranged to flow via said inlet 12 to said first fluid transport member 17, from said first fluid transport member through said channels 16 to the second fluid transport member 18 and further to the outlet 14.

The heat exchanger could have any suitable design. The heat exchanger could e.g. have inlet and outlet arranged at one of said first and second fluid transport members.

During cleaning operation the arrangement according to the present invention is attached to the inlet 12 and outlet 14 as described with reference to fig. 1 above and with reference to fig. 3 below.

Fig, 3a schematically illustrates an arrangement 20 for cleaning a heat exchanger 10 according to an embodiment of the present invention.

The heat exchanger 10 comprises an inlet 12 which, during intended heating operation of the heat exchanger 10, is configured to receive a fluid, e.g. a heated coolant from the engine of a vehicle. The heat exchanger 10 comprises a plurality of channels 16 and an outlet 14 for exhausting said fluid, said inlet 12 and outlet being fluidly connected to said channels 18.

The arrangement 20 comprises a supply pipe 21 configured to, during a cleaning operation, be attached to said inlet 12 or outlet 14 for providing hot fluid to said heat exchanger 10. In fig. 3a said supply pipe 21 is attached to said inlet 12 of the heat exchanger 10.

The arrangement 20 further comprises means 22 for providing hot fluid through said supply pipe 21 . The means 22 for providing hot fluid through said supply pipe 21 may comprise any suitable means or providing hot fluid through said supply pipe 21. The means 22 for providing hot fluid through said supply pipe 21 comprises according to an embodiment a tap arrangement from the municipai water pipelines. Hereby the hot fluid is hot water from the municipai water pipelines.

The arrangement 20 further comprises means 23 for supplying pressurized air in pulses to said supply pipe 21 so as to provide said hot fluid to an increased flow rate through said plurality of channels 16 for cleaning said channels 16. Said pressurized air is arranged to be provided to said supply pipe at a pressurized air supply 21 i of said supply pipe 21 , i.e. an air inlet 21 i of said supply pipe for introducing said pressurized air in pulses to said supply pipe 21 .

The means 23 for supplying pressurized air in pulses to said supply pipe 21 comprises a supply member 23a for said hot fluid. Said supply member 23a is according to an embodiment a supply member such as a water tap configuration from which hot water from the municipal hot water pipeline is provided.

The means 23 for supplying pressurized air in pulses to said supply pipe 21 comprises a regulator member 23b for controlling said air pulses. The means 23 for supplying pressurized air in pulses to said supply pipe 21 comprises a valve member 23c configured to allow or prevent said pressurized air to said supply pipe 21 . Said valve member 23c is configured to be controlled by means of said regulator member 23b. Said valve member 23c is according to an embodiment a magnetic valve.

The means 23 for supplying pressurized air in pulses to said supply pipe 21 comprises an air supply pipe 23d. Said air supply pipe 23d is connected to said supply member 23a. Said air supply pipe 23d is connected to said regulator 23b. Said air supply pipe 23d is connected to said valve member 23c. According this embodiment of the arrangement said pressurized air pulse flow is arranged to be provided based on amount of fluid to be provided to said heat exchanger 10 and/or length L of supply pipe 21 a from said pressurized air supply 21 i to said heat exchanger 10 and/or cross sectional area of supply pipe 21 . The length of said supply pipe may be in the range of a metre or a few meters.

Fig. 3b schematically illustrates a cross sectional view X-X of the supply pipe 21 of the arrangement 20 in fig. 3a, illustrating the cross sectional area A of said supply pipe 21 . In fig. 3b the supply pipe 21 is illustrated as having a circular cross section. The supply pipe 21 may however have any suitable ring shaped cross section for allowing said hot fluid to flow and be accelerated by means of said pressurized air in pulses. Said supply pipe may have any suitable cross sectional area. Said supply pipe has according to an embodiment a cross sectional area in the range of 1 -15 cm 2 , according to an embodiment about 3-4 cm 2 . Thus, said pressurized air pulse is supplied to the supply pipe 21 from the means 23 for supplying pressurized air in pulses so that said hot fluid is accelerated in a portion 21 a of said supply pipe towards the heat exchanger 10, said portion 21 a of said supply pipe 21 having a length L. The supply pipe 21 comprises said pressurized air supply 21 i, i.e. said air inlet 21 i for introducing said pressurized air in pulses into said supply pipe 21.

The hot fluid is thus arranged to be accelerated to said increased flow rate by means of said means 23 for supplying pressurized air in pulses. Thus, the pressurized air is arranged to be supplied in pulses by said means

23 to said supply pipe 21 so as to provide said hot fluid to an increased flow rate through said plurality of channels 16 of said heat exchanger 10 for cleaning said channels 16. Said air pulses and pressure of said pressurized air are arranged to be adapted to optimize acceleration of said hot fluid to an increased flow rate without mixing the fluid, e.g. water, with air to any significant extent. Mixing of air and said hot fluid is preferably avoided to the extent possible. Said air pressure of said pressurized air is adapted to the heat exchanger, i.e. the dimensions of the heat exchanger comprising the dimensions of the plurality of channels of the heat exchanger and the dimensions of the supply pipe. Said air pressure of said pressurized air is according to an embodiment in the range of about 2-5 bar, according to an embodiment in the range of 3-4 bar.

Prior to attaching said supply pipe 21 to said inlet 12 the connection to said inlet 12 for the intended operation of the heat exchanger 10 has been detached.

According this embodiment the arrangement 20 further comprises a check valve 24 arranged upstream of said pressurized air supply. Said check valve

24 is thus arranged upstream of said air inlet 21 i of said supply pipe 21 .

Said check valve 24 is configured to prevent said hot fluid from being pushed back through said supply pipe 21 . Said check valve 24 is thus a one-way valve.

According this embodiment the arrangement 20 further comprises a safety valve 25 arranged downstream of said pressurized air supply. Said safety valve 25 is thus arranged downstream of said air inlet 21 i of said supply pipe 21 .

Said safety valve 25 is configured to prevent said flow of hot fluid through said heat exchanger 10 if the pressure of said hot fluid flow exceeds a predetermined pressure. Said safety valve 25 is configured to allow said flow of hot fluid passed said heat exchanger 10, i.e. to exhaust said flow of hot fluid, if the pressure of said hot fluid flow exceeds a predetermined pressure.

According this embodiment the arrangement 20 further comprises a pressure sensor 26 for detecting the pressure in the supply pipe. Said pressure sensor 26 is arranged downstream of said pressurized air supply. Said pressure sensor 26 is thus arranged downstream of said air inlet 21 i of said supply pipe 21 .

According this embodiment the arrangement 20 further comprises an exhaust pipe 27 configured to be attached to the other of said inlet 12 or outlet 14 for exhausting said fluid having passed through said plurality of channels 16 of said heat exchanger 10. In this embodiment the exhaust pipe 27 is attached to the outlet 14 for exhausting said fluid having passed through said heat exchanger 10.

In fig, 3a said supply pipe 21 is attached to said inlet 12 wherein said hot fluid is arranged to be provided through said supply pipe 21 and accelerated by means of said means 23 for supplying pressurized air in pulses through said plurality of channels 16 to said outlet 14 and further through said exhaust pipe 27 for cleaning said channels 16 of the heat exchanger 10.

According to an embodiment supply pipe 21 of the arrangement 20 could thereafter or prior to that be attached to said outlet 14 wherein said hot fluid is arranged to be provided through said supply pipe 21 and accelerated by means of said means 23 for supplying pressurized air in pulses the opposite way through said plurality of channels 16 to said inlet for cleaning said channels 16. Fig, 4 schematically illustrates a method for cleaning a heat exchanger according to an embodiment of the present invention.

Said heat exchanger comprising an inlet which, during intended heating operation of the heat exchanger, is configured to receive a fluid, a plurality of channels through which said fluid is arranged to flow for heating air passing between said channels during said intended heating operation, and an outlet for letting out the thus received fluid.

According to the embodiment the method for cleaning a heat exchanger comprises a step S1. In this step a supply pipe is attached to said inlet or outlet for providing hot fluid to said heat exchange.

According to the embodiment the method for cleaning a heat exchanger comprises a step S2. In this step hot fluid is provided through said supply pipe.

According to the embodiment the method for cleaning a heat exchanger comprises a step S3. In this step pressurized air is supplied in pulses to said supply pipe so as to provide said hot fluid to an increased flow rate through said plurality of channels for cleaning said channels.

The pressurized air provided in pulses may be adapted such that an increased flow rate of said hot fluid is obtained without mixing the fluid, e.g. water, with air to any significant extent. For such a heat exchanger being arranged in a vehicle, e.g. a cab of a truck, the heat exchanger does not need to be removed from the cab, only connections to inlet and outlet need to be detached. Hereby cleaning may be efficiently performed in a workshop utilizing municipal hot water as fluid and pressurized air available in the workshop. Cleaning may be required only during a few minutes in order to have a good result of said cleaning of said heat exchanger.

The hot fluid is thus accelerated to said increased flow rate by means of said pressurized air in pulses. Flow rate of said hot fluid refers to flow velocity. Thus, the step of supplying pressurized air in pulses to said supply pipe so as to provide said hot fluid to an increased flow rate through said plurality of channels for cleaning said channels comprises adapting the pulses and air pressure to optimize acceleration of said hot fluid to an increased flow rate without mixing the fluid, e.g. water, with air to any significant extent. Mixing of air and said hot fluid is preferably avoided to the extent possible. According to an embodiment said pulses of pressurized air are provided with a frequency of about 1 Hz, i.e. 0.5 seconds on and 0.5 seconds off. Said pulses of pressurized air may be provided with any suitable interval and may according to an embodiment be different on time, i.e. time during which pressurized air is provided to the supply pipe, compared to the off time, i.e. time during which said pressurized air is prevented from be provided to said supply pipe, e.g. a longer on time than off time.

Prior to attaching said supply pipe to said inlet or outlet the connection to said inlet/outlet for the intended operation of the heat exchanger is detached.

According to an embodiment of the method said supply pipe is attached to said inlet wherein said hot fluid is provided through said supply pipe and accelerated by means of said pressurized air in pulses through said plurality of channels to said outlet for cleaning said channels and thereafter or prior to that said supply pipe is attached to said outlet wherein said hot fluid is provided through said supply pipe and accelerated by means of said pressurized air in pulses the opposite way through said plurality of channels to said inlet for cleaning said channels.

Said air pressure of said pressurized air is adapted to the heat exchanger, i.e. the dimensions of the heat exchanger comprising the dimensions of the plurality of channels of the heat exchanger and the dimensions of the supply pipe. Said air pressure of said pressurized air is according to an embodiment in the range of about 2-5 bar, according to an embodiment in the range of 3-4 bar, which may be suitable for a heat exchanger where said plurality of channels have a cross sectional area in the range of square millimetres. According to an embodiment of the method said pressurized air pulse flow is provided based on amount of fluid to be provided to said heat exchanger and/or length of supply pipe from pressurized air supply to heat exchanger and/or cross sectional area of supply pipe. The length of said supply pipe may be in the range of a metre or a few meters. Said supply pipe may have any suitable cross sectional area. Said supply pipe has according to an embodiment a cross sectional area in the range of 1 -15 cm 2 , according to an embodiment about 3-4 cm 2 .

According to an embodiment the method further comprises the step of preventing said hot fluid from being pushed back through said supply pipe by means of a check valve arranged upstream of said pressurized air supply.

According to an embodiment the method further comprises the step of preventing said flow of hot fluid through said heat exchanger by means of a safety valve arranged downstream of said pressurized air supply if the pressure of said hot fluid flow exceeds a predetermined pressure.

According to an embodiment of the method said fluid is water. By thus using water for said cleaning operation hot water from the municipal water pipelines may advantageously be used.

According to an embodiment the method further comprises the step of, in connection to attaching said supply pipe, attaching an exhaust pipe to the other of said outlet or inlet for exhausting said fluid having passed through said plurality of channels.

Prior to attaching said exhaust pipe to said inlet or outlet the connection to said inlet/outlet for the intended operation of the heat exchanger is detached. The foregoing description of the preferred embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilied in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated.