Heat-pipe system and method of and apparatus for controlling a flow rate of a working fluid in a liquid pipe of the heat pipe system

• US 4,898,231 A
• Filed: 11/10/1988
• Issued: 02/06/1990
• Est. Priority Date: 09/30/1985
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Miyazaki, Yoshiro
• Primary Examiner(s): Davis, Jr., Albert W.
• Application Number:
  US07/285,311
• Time in Patent Office: 453 Days
• Field of Search: 165/104.25, 165/104.24, 165/13, 165/32, 122/366
• US Class Current: 165/274
• CPC Class Codes: F28D 15/0233 the conduits having a particular shape, e.g. non-circular cross-section, annular F28D15/0241, F28D15/0266 take precedence
• CPC Class Codes: F28D 15/043 forming loops, e.g. capillary pumped loops
• CPC Class Codes: F28D 15/06 Control arrangements therefor
• CPC Class Codes: F28F 2200/005 Testing heat pipes

Abstract

A heat-pipe system of the two-phase fluid loop type comprising a liquid duct as a main loop for circulating a working fluid in liquid phase by a pump, an evaporator having a first capillary structure to which the working fluid is supplied from high pressure side of the main loop, a condenser having a second capillary structure for returning liquid condensate to the low pressure side of the man loop after radiating heat in the condenser, and a bypass pipe connected between the evaporator and the radiator for transporting vapor evaporated in the evaporator through its capillary structure to the second capillary of the condenser. With this construction, since the working fluid is circulated by the pump while the supply of the liquid corresponding to that evaporated in the capillary structure of the evaporator is carried out by the capillary force in the evaporator, a large amount of heat can be transported over long distances. A method of and apparatus for controlling a flow rate of a working fluid in a liquid duct of the heat-pipe system is also disclosed.

Claims

1. A heat-pipe system which comprises:

an evaporator having a first capillary structure for evaporating a working fluid;

a condenser having a second capillary structure for condensing vapor evaporated in said evaporator into liquid condensate so as to return it to the evaporator through a liquid duct;

a vapor transport pipe communicating between vapor channels of said evaporator and said condenser for transporting the vapor evaporated in the evaporator;

a pump provided at the liquid duct for driving the working fluid therethrough;

sensor means for detecting the change in the amount of liquid in the capillary structure of the evaporator in accordance with the pressure difference between vapor pressure in the vapor channel and liquid pressure in the liquid channel of the evaporator; and

control unit means having a CPU, a ROM, and a RAM, connected between said pump and said sensor means for controlling the rotational speed of the pump in accordance with a detected signal from said sensor means so as to optimally control the amount of the liquid remaining in the capillary structure of the evaporator by controlling a flow rate of the liquid flowing through the liquid duct.

2. The heat-pipe system as claimed in claim 1 wherein said sensor means further comprises an elongated pipe, one end of which is communicated with vapor in the vapor channel and the other end of which is communicated with liquid in the liquid channel in the evaporator, a plurality of thermocouples provided along the elongated pipe, and a heater provided along said elongated pipe so as to heat the pipe.

4. A method of controlling a flow rate of a working fluid in a liquid duct of a heat-pipe system, paticularly an arterial heat-pipe system having evaporator and condenser, which comprises the steps of:

detecting the position of interface between vapor and liquid in an elongated pipe of a sensor means for detecting the liquid amount;

calculating P_V -P_L from the difference between capillary force Pcap in the elongated pipe of the sensor means and head height due to the self weight of the liquid in the elongated pipe (where P_V =vapor pressure in the vapor channel and P_L =liquid pressure in the liquid channel of the evaporator);

determining if P_V -P_L <

Pcap. max is found (where Pcap. max=maximum capillary force in the vapor channel of the evaporator);

increasing the rotational speed of a pump provided at the liquid duct if the result of said determination is NO and repeating this operation until it reaches a desired result;

determining if 0<

P_V -P_L is found, in accordance with the result of said first determination, i.e., YES is found;

decreasing the rotational speed of the pump if the result of the last determination is NO, i.e., 0≧

P_V -P_L is found; and

returning the operation to the first step of detecting the position of interface when the last determination is YES, that is, 0<

P_V -P_L is found, thereby optimally controlling the amount of liquid remaining in the capillary structure of the evaporator.

3. The heat-pipe system as claimed in claim 4 wherein said elongated pipe is tapered so as to more easily detect the position of interface between the vapor and the liquid in the elongated pipe in a zero gravity state such as in the cosmic space.