Heat Transfer Arrangement and Electronic Housing Comprising a Heat Transfer Arrangement and Method of Controlling Heat Transfer

Abstract

A heat transfer arrangement comprises a refrigerant circuit ( 102 ). The refrigerant circuit ( 102 ) comprises an evaporator ( 104 ) adapted to be arranged inside an electronic component housing ( 202 ), a condenser ( 108 ) adapted to be arranged outside the electronic component housing ( 202 ), a first conduit leading ( 106 ) from the evaporator ( 104 ) to the condenser ( 108 ), and a second conduit leading from the condenser ( 108 ) to the evaporator ( 104 ). A refrigerant is present in the refrigerant circuit ( 102 ) and in use, under first temperature conditions, is arranged to self-circulate in the refrigerant circuit ( 102 ) by evaporating in the evaporator ( 104 ), rising as a gas through the first conduit, condensing in the condenser ( 108 ) and flowing through the second conduit to the evaporator ( 104 ). In the refrigerant circuit ( 102 ) a further separate gas or separate gas mixture is present in a quantity such that in use, under second temperature conditions, said quantity of further separate gas or separate gas mixture expands inside the condenser ( 108 ) to thereby displace refrigerant from the condenser ( 108 ). Heat transfer is thus controlled. Also an electronic component housing comprising such a heat transfer arrangement and a method of controlling heat transfer from such an electronic housing are provided.

1 . A heat transfer arrangement comprising a refrigerant circuit comprising:
 an evaporator adapted to be arranged inside an electronic component housing,   a condenser adapted to be arranged outside the electronic component housing, said condenser being separate from and arranged above said evaporator,   a first conduit leading from the evaporator to the condenser, and   a second conduit leading from the condenser to the evaporator,   wherein a refrigerant is present in the refrigerant circuit and in use, under first temperature conditions, is arranged to self-circulate in the refrigerant circuit by means of gravity and buoyancy forces whereby said refrigerant is evaporating in the evaporator, rising as a gas through the first conduit, condensing in the condenser and flowing through the second conduit to the evaporator and wherein the refrigerant circuit comprises a further separate gas or separate gas mixture which is present in a quantity such that in use, under second temperature conditions, said quantity of further separate gas or separate gas mixture expands inside the condenser to thereby displace refrigerant from the condenser such that heat transfer in the condenser is reduced.   
     
     
         2 . The heat transfer arrangement according to  claim 1 , wherein a constant weight of the refrigerant and a constant weight of the further separate gas or separate gas mixture are present in the refrigerant circuit. 
     
     
         3 . The heat transfer arrangement according to  claim 1 , wherein the further separate gas or separate gas mixture is present in the refrigerant circuit at a fixed weight ratio with respect to the refrigerant. 
     
     
         4 . The heat transfer arrangement according to  claim 3 , wherein the weight ratio of the further separate gas or gas mixture is in the interval of 3%-40% of the refrigerant. 
     
     
         5 . The heat transfer arrangement according to  claim 4 , wherein the weight ratio of the further separate gas or gas mixture is in the interval of 5%-25% of the refrigerant. 
     
     
         6 . The heat transfer arrangement according to  claim 1 , wherein the refrigerant has a molecular structure referred to as R134a. 
     
     
         7 . The heat transfer arrangement according to  claim 1 , wherein the separate gas is nitrogen or the separate gas mixture is air. 
     
     
         8 . The heat transfer arrangement according to  claim 1 , wherein an outer heat transfer surface of the condenser and/or the evaporator is/are arranged at an angle (α) of 5-60 degrees from a horizontal line. 
     
     
         9 . An electronic component housing comprising a heat transfer arrangement according to  claim 1  and further comprising a first gas moving device for circulating a gas such as air inside the electronic component housing over an outer surface area of the evaporator. 
     
     
         10 . The electronic component housing according to  claim 9 , comprising a second gas moving device for blowing ambient air over an outer surface area of the condenser. 
     
     
         11 . The electronic component housing according to  claim 9 , wherein the electronic component housing is part of a radio base station. 
     
     
         12 . A method of controlling heat transfer from an electronic component housing according to  claim 9 , to an environment, comprising the steps of:
 self-circulating the refrigerant in the refrigerant circuit, under first temperature conditions, by means of gravity and buoyancy forces whereby said refrigerant is evaporating in the evaporator, rising as a gas through the first conduit, condensing in the condenser and flowing through the second conduit to the evaporator,   controlling the second gas moving device,   stopping the second gas moving device when heat transfer is to be reduced and,   displacing the refrigerant from the condenser, under second temperature conditions, when a pressure inside the refrigerant circuit is reduced and the separate gas or separate gas mixture expands inside the condenser such that heat transfer in the condenser is reduced.   
     
     
         13 . The method of controlling heat transfer according to  claim 12 , comprising a step of:
 controlling the first gas moving device to circulate a gas inside the electronic component housing over the outer surface area of the evaporator.   
     
     
         14 . The method of controlling heat transfer according to  claim 13 , wherein the step of controlling the first gas moving device includes,
 reducing a speed of the first gas moving device to a minimum speed when a limit temperature, in the interval of +5 to +30 degrees Celsius, inside the electronic component housing is reached, and   maintaining the minimum speed when a temperature inside the electronic component housing is lower than the limit temperature.   
     
     
         15 . The method of controlling heat transfer according to  claim 12 , wherein the step of stopping the second gas moving device is performed when a temperature inside the electronic component housing is in the interval of +5 to +20 degrees Celsius and the second gas moving device is maintained stopped at even lower temperatures inside the electronic component housing.