A cooling system comprising: a compressor; a condenser; an expansion valve; and a heat exchanger comprising: a vessel for containing a refrigerant, the vessel having an inner space bounded by a closed surface of a vessel wall, the vessel comprising an inlet and an outlet for transport of refrigerant into and out of the inner space through the vessel wall, and a tube at least partly inside the inner space, wherein a first end of the tube is fixed to a first orifice of the vessel wall and a second end of the tube is fixed to a second orifice of the vessel wall to enable fluid communication into and/or out of the tube through the first orifice and the second orifice; wherein the vessel of the heat exchanger is connected with the compressor, the condenser, and the expansion valve by means of the inlet and outlet, forming at least one refrigeration cycle in which the heat exchanger is an evaporator, characterized by a pressure control means configured to control a pressure in the inner space based on a target temperature; and the closed surface of the vessel wall of the heat exchanger presenting a hole extending all the way through the vessel, wherein the tube has at least one winding around a wall portion of said vessel wall, which wall portion defines said hole. a compressor; a condenser; an expansion valve; and a heat exchanger comprising: a vessel for containing a refrigerant, the vessel having an inner space bounded by a closed surface of a vessel wall, the vessel comprising an inlet and an outlet for transport of refrigerant into and out of the inner space through the vessel wall, and a tube at least partly inside the inner space, wherein a first end of the tube is fixed to a first orifice of the vessel wall and a second end of the tube is fixed to a second orifice of the vessel wall to enable fluid communication into and/or out of the tube through the first orifice and the second orifice; wherein the vessel of the heat exchanger is connected with the compressor, the condenser, and the expansion valve by means of the inlet and outlet, forming at least one refrigeration cycle in which the heat exchanger is an evaporator, characterized by a pressure control means configured to control a pressure in the inner space based on a target temperature; and the closed surface of the vessel wall of the heat exchanger presenting a hole extending all the way through the vessel, wherein the tube has at least one winding around a wall portion of said vessel wall, which wall portion defines said hole. a vessel for containing a refrigerant, the vessel having an inner space bounded by a closed surface of a vessel wall, the vessel comprising an inlet and an outlet for transport of refrigerant into and out of the inner space through the vessel wall, and a tube at least partly inside the inner space, wherein a first end of the tube is fixed to a first orifice of the vessel wall and a second end of the tube is fixed to a second orifice of the vessel wall to enable fluid communication into and/or out of the tube through the first orifice and the second orifice; wherein the vessel of the heat exchanger is connected with the compressor, the condenser, and the expansion valve by means of the inlet and outlet, forming at least one refrigeration cycle in which the heat exchanger is an evaporator, characterized by a pressure control means configured to control a pressure in the inner space based on a target temperature; and the closed surface of the vessel wall of the heat exchanger presenting a hole extending all the way through the vessel, wherein the tube has at least one winding around a wall portion of said vessel wall, which wall portion defines said hole.