Radiators

Abstract: A thermosyphon radiator comprising a sealed panel (1) is formed into two or more discrete chambers (6,8), each containing a reservoir of vaporising liquid in a lowermost part of the panel and a heating member (3) extending with clearance through the lowermost part of the panel (1), the member being at least partially immersed in the vaporising liquid.

Description: This invention relates to thermosyphon radiators. Thermosyphon radiators are of the type in which a vaporising liquid contained within a sealed panel is heated, in use, by a heating pipe passing through the vaporising liquid. A radiator which operates on the thermosyphon principle is described in GB published patent application no: 2286881. This type of radiator provides advantages of speed of response, even temperature and isolation of the heating system water from the main body of the radiator. US - 5 156 208 and FR - A - 2 654 808 disclose thermosyphon radiators each of which may be said to comprise a sealed panel formed into two or more discrete chambers, each containing a reservoir of vaporising liquid in a lowermost part of the panel and a heating member extending through the lowermost part of the panel, the member being at least partially immersed in the vaporising liquid. One problem with radiators such as that of GB 2286881 is that a single sealed panel when operated under vacuum conditions, will operate at uniform pressure and therefore the chamber will also operate at uniform temperature. This means that the radiator chamber temperature cannot exceed the radiator system water outlet temperature and consequently the heat output of the radiator is limited compared with a conventional panel radiator. For example, a conventional radiator would have a mean surface temperature of approximately 70° C if the heating pipe inlet and exit water temperature were 80°C and 60°C respectively. With a thermosyphon radiator, the mean surface temperature is limited to less than the return water temperature, i.e. 60°C which has the effect of reducing the heat output of the radiator significantly. It is therefore an object of the present invention to provide a thermosyphon radiator which increases the effective heat output of the radiator for a given overall size and can more closely achieve the heat output of a conventional radiator. The invention described here provides improved performance compared with a standard thermosyphon radiator. The original radiator operates with a single chamber which is evacuated and allows the vaporising liquid to boil off once heat is applied to the heating pipe. The performance of this radiator is restricted to the pressure which corresponds to the lowest temperature in the system. In a single chamber design, the vacuum pressure is equal within the compartment and the temperature is therefore also uniform and maintained at a level corresponding to the minimum temperature in the heating pipe. According to the present invention, we provide a thermosyphon radiator comprising a sealed panel wherein the panel is formed into two or more discrete separated chambers, arranged in series, each containing a reservoir of vaporising liquid in a lowermost part of the panel and a heating member extending through the lowermost part of the panel forming a clearance with the inner walls of the reservoir, the member being at least partially immersed in the vaporising liquid entering at one side of the reservoir and leaving at the other side and passing in series from one chamber to the other. The vaporising liquid may be water, but ammonia, methanol or acetone are viable alternatives. Preferably, the member is a pipe for carrying a second liquid. Suitably, the pipe is covered externally with a fine metallic mesh, compacted metallic wool, fibrous material or a polymeric coating. Alternatively, the pipe can be coated with a porous material such as a sintered metallic or ceramic material. Conveniently, the pipe is immersed in the vaporising fluid, e.g. water, to a depth of no less than three - quarters of the diameter of the pipe. The panel may be of pressed steel or roll - bonded aluminium, which may be pre - treated to inhibit corrosion. Each reservoir may be hermetically sealed and preferably each chamber is evacuated except for the vaporising liquid. The radiator may be externally finned to increase the heat transfer to the space to be heated. Suitably the water is distilled water and may contain corrosion inhibitors. This invention uses two or more chambers which are arranged in series with the heating pipe. In this case the two (or more) chambers will operate at pressures corresponding to the minimum temperatures in each chamber. As the heating pipe passes in series from chamber A to B, the minimum temperature of water in compartment A will be higher than compartment B. Taking the example shown in figure 1, if the inlet and exit temperatures to chamber A are 80°C and 70°C respectively, the vacuum pressure in compartment A will correspond to 70°C. Then the inlet and exit temperatures to compartment B could be 70°C and 60°C and therefore the vacuum pressure to compartment B will correspond to 60°C. In a single chamber design operating with inlet and exit temperatures of 80°C and 60°C, the vacuum pressure will correspond to 60°C. Therefore a single chamber radiator will have a surface temperature of approximately 60°C and a radiator with two chambers would have a surface temperature of approximately 65°C (i.e. half of the radiator is at 60°C and the other half at 70°C). Since the heat output of the radiator depends on its surface temperature, a multi-chamber radiator will provide higher heat output than an equivalent size single chamber radiator. Am embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which:- Figure 1 is a perspective view of the radiator; and Figure 2 is a cross sectional view of the radiator. Referring to the drawings, the radiator comprises a conventional sealed panel having a lowermost part 2 through which a pipe 3 enters at one side 4 and leaves by the other side 5. The pipe 3 may be a hot water pipe supplied with hot water from a boiler (not shown) and is joined to the panel 1. The panel 1 is divided into two chambers A and B and hermetically sealed and evacuated except for the vaporising liquid. It can be divided into more than two chambers but this is not shown in the drawing. The lowermost part 2 of the panel which is also divided into two (or more) reservoirs, 6 and 8, corresponding to chambers A and B and each contain a reservoir of water (Fig 2) and the pipe 3, which extends with clearance through the internal panel sides formed by the lowermost part 2 in both chambers A and B. Chambers A and B (and C, D, etc) are filled with vaporising liquid and then sealed for life using pre - formed connection points. When hot water, from a boiler for example, passes through the pipe 3, the water begins to boil extracting latent heat from the pipe 3 and the vapour so produced rises to the upper part of the radiator panel in both chambers A and B where it condenses on the inside surface to give out its latent heat to the panel surfaces and therefore to the space to be heated. The condensate then trickles back down to the reservoirs 6 and 8. The action of boiling and condensation in each chamber A and B are separate and therefore chamber A can operate at a higher temperature than chamber B assuming the flow in the heating pipe is into reservoir A and then B.

Claims: A thermosyphon radiator comprising a sealed panel (1), wherein the panel is formed into two or more discrete separated chambers (A, B) arranged in series each containing a reservoir (6, 8) of vaporising liquid in a lowermost part (2) of the panel and a heating member (3) extending through the lowermost part of the panel forming a clearance with the inner walls of the reservoir, the member (3) being at least partially immersed in the vaporising liquid entering at one side of the reservoir and leaving at the other side and passing in series from one chamber to the other. A thermosyphon radiator as claimed in claim 1, in which the liquid comprises water, ammonia, methanol or acetone. A radiator as claimed in claim 1 or claim 2, in which the member (3) is a pipe for carrying a second liquid. A radiator as claimed in claim 3, in which the pipe (3) is covered externally with a fine metallic mesh, compacted metallic wool, fibrous material or a polymeric coating. A radiator as claimed in claim 3, in which the pipe (3) is coated with a porous material. A radiator as claimed in claim 3, in which the pipe (3) is immersed in the vaporising liquid to a depth of no less than three - quarters of the diameter of the pipe (3). A radiator as claimed in claim 3, in which the pipe is immersed in water to a depth of no less than three - quarters of the diameter of the pipe (3). A radiator as claimed in any of the preceding claims in which the panel (1) is of pressed steel or roll - bonded aluminium. A radiator as claimed in any of the preceding claims in which each reservoir (6, 8) is hermetically sealed. A radiator as claimed in any of the preceding claims in which each chamber (A, B) is evacuated. A radiator as claimed in any of the claims 2 to 9 in which the liquid is distilled water. A radiator as claimed in any of the preceding claims in which the panel (1) is externally finned.

Inventors: SHIRET ALAN REGINALD, SHIRET, ALAN REGINALD
Applicants: LATTICE INTELLECTUAL PROPERTY, LATTICE INTELLECTUAL PROPERTY LIMITED
Application year: 1997
Main classification: F28D15
IPC codes: F28D1, F28D15