Temperature-Controlled Variable Fluidic Resistance Device
A thermally controlled variable restrictor device provides variable restriction of fluid flow by temperature-induced viscosity changes. The thermally controlled variable restrictor device allows fast variable fluid control by employing a thermo-electric heater-cooler in intimate contact with a fluid channel containing a fluid thereby effecting rapid viscosity changes in the flowing fluid. The permeability and flow rate of fluids through the variable restrictor device can be manipulated by changing the temperature of a restriction element.
1 . An apparatus for variably restricting a flow of a fluid, comprising:
a restriction element defining at least one fluid channel and comprising means for heating and cooling a fluid in the at least one fluid channel; and
means for controlling the means for heating and cooling.
2 . The apparatus of claim 1 , wherein the restriction element comprises a flattened length of tubing.
3 . The apparatus of claim 1 , wherein the at least one fluid channel has a serpentine shape.
4 . The apparatus of claim 1 , wherein the at least one restriction element comprises a micro-fluidic component.
5 . The apparatus for variable restriction of claim 1 , wherein the means for heating and cooling comprises a cooling unit.
6 . The apparatus of claim 5 , wherein the restriction element further comprises a conduit, and the means for heating and cooling comprises a thermo-electric heater-cooler in intimate contact with the conduit.
7 . The apparatus of claim 5 , wherein the cooling unit comprises a Peltier thermo-electric heat pump.
8 . The apparatus of claim 5 , wherein the cooling unit comprises means for passive cooling.
9 . The apparatus of claim 1 , wherein the means for heat and cooling comprises a resistance-heating element in thermal contact with the at least one fluid channel.
10 . The apparatus of claim 9 , wherein the restriction element comprises a length of tubing that defines the at least one fluid channel, and the resistance-heating element is an integral portion of the length of tubing.
11 . The apparatus of claim 1 , further comprising a flow sensor in fluid communication with the at least one fluid channel.
12 . The apparatus of claim 11 , wherein the flow sensor and the means for heating and cooling are in communication with a flow controller.
13 . An apparatus for variably restricting a flow of a fluid, comprising:
a thermo-electric heat pump having a cold face and a hot face;
means for controlling the thermo-electric heat pump;
a first fluid channel defined by a first restriction element, the first fluid channel being in thermal communication with the cold face of the thermo-electric heat pump; and
a second fluid channel defined by a second restriction element, the second fluid channel being in thermal communication with the hot face of the thermo-electric heat pump.
14 . The apparatus of claim 13 , further comprising a first flow sensor in fluid communication with the first fluid channel, and a second flow sensor in fluid communication with the second fluid channel.
15 . The apparatus of claim 14 , wherein the first flow sensor and second flow sensor are in communication with a flow controller.
16 . The apparatus of claim 15 , wherein the flow controller is in communication with the thermo-electric heat pump.
17 . The apparatus of claim 16 , further comprising a first resistance-heating element in thermal contact with the first fluid channel and a second resistance-heating element in thermal contact with the second fluid channel.
18 . A method for controlling a flow of a fluid, comprising;
providing a fluid channel in thermal communication with electrical means for heating and cooling;
providing control means in communication with the electrical means for heating and cooling; and
adjusting fluid flow within the fluid channel by varying a temperature of a fluid flowing in the channel in response to control of the electrical means for heating and cooling.
19 . The method of claim 18 , wherein the electrical means for heating and cooling comprises a Peltier thermo-electric heat pump.
20 . The method of claim 18 , wherein the electrical means for heating and cooling comprises a resistance-heating element.