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HEAT EXCHANGE SYSTEM FOR ROTATING ANODE-TYPE X-RAY TUBE

IP.com Disclosure Number: IPCOM000032933D
Publication Date: 2004-Nov-19
Document File: 6 page(s) / 136K

Publishing Venue

The IP.com Prior Art Database

Abstract

A heat exchange system comprises an evaporator filled with a heat exchange medium such as liquid sodium, and coupled to a heat source (e.g. anode) within an X-ray tube. A condenser that is configured in combination with a bearing that supports the anode is arranged in fluid communication with the evaporator. A liquid metal such as Gallium or Gallium alloy filled in the bearing cools the heat exchange medium flowing from the evaporator towards the condenser. One or more auxiliary thermodynamic elements are accommodated within the condenser, to exchange further cool down the heat exchange medium.

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HEAT EXCHANGE SYSTEM FOR ROTATING ANODE-TYPE X-RAY TUBE

BACKGROUND OF THE INVENTION

[0001]   This invention relates generally to heat exchange systems, and more particularly, to heat exchange systems for rotating anode type X-ray tubes.

[0002]    Generally, at higher loads (e.g. above 5 kW), target temperatures are quite high as the rotational speeds need to be increased dramatically leading to a risk of increased noise.  Also above 100kW peak power specification, focal spot temperatures are around 3000’ C that is beyond the safe limit.

[0003]   Furthermore, bearings that support the anode undergo tremendous thermal stresses due to increase in temperature.  The safe limit of operation of these bearings is less than 450oC.  Once this temperature is reached and further increases, the life of the bearing drops exponentially resulting in early failure.  This is accompanied by steep fall of Rockwell hardness after 500 C, which indicates fall in all the crucial mechanical properties.

[0004]    Thermal simulation results with known cooling systems reveals that the temperature at the front inner race reaches 538 oC  and the bearing cannot withstand this condition as the temperature is exceeding the safety limit by a huge margin. 

[0005]    Therefore, an effective heat exchange system which can work in the temperature conditions prevailing in the X-ray tube, and provide:

(i)                  a quick thermal cycling of the heat exchanging fluid;

(ii)                no issues posed with respect to the rotor dynamic stability of the anode assembly;

(iii)               no arcing / electrical related issues;

(iv)              easy manufacturability of the heat exchanger chamber;

(v)                minimal design changes in the system for implementing the heat exchange-chamber into the system, is necessary.

BRIEF SUMMARY OF THE INVENTION

[0006]    In an embodiment, a heat exchange system comprises an evaporator filled with a heat exchange medium and coupled to a heat source (e.g. anode) within an X-ray tube.  A condenser that is configured in combination with a bearing that supports the anode is arranged in fluid communication with the evaporator.  A liquid metal (e.g. liquid lithium) filled in the bearing cools the heat exchange medium flowing from the evaporator towards the condenser.  A plurality of wicks is disposed within the condenser, to facilitate flow of liquid lithium from the condenser to the evaporator. 

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]   FIG.  1 shows the schematic diagram of the heat exchange assembly according to one embodiment of the present invention.

[0008]   FIG.  2 shows a perspective of the hollow shaft according to one embodiment of the present invention.

 

DETAILED DESCRIPTION OF THE DRAWINGS 

[0009]    Various embodiments of this invention provide a heat exchange system for X-ray tubes, especially those accommodating rotary anode.

[0010]    FIG.1 shows an embodiment, wherein the heat exchange system comprises an evaporator filled with a heat exchange medium and coupled to a heat source (e.g. anod...