Method of cooling series-connected heat sink modules

A method of cooling two or more heat-providing surfaces using a cooling apparatus comprising two or more fluidly connected heat sink modules arranged in a series configuration, the method comprising:

• providing a flow of single-phase liquid coolant to a first inlet port of a first heat sink module mounted on a first heat-providing surface, the single-phase liquid coolant having a predetermined pressure and a predetermined temperature at the first inlet port of the first heat sink module, the predetermined temperature being slightly below a saturation temperature of the single-phase liquid coolant at the predetermined pressure;
• projecting the flow of single-phase liquid coolant against the first heat-providing surface within the first heat sink module, wherein a first amount of heat is transferred from the first heat-providing surface to the flow of single-phase liquid coolant thereby inducing phase change in a portion of the flow of single-phase liquid coolant and thereby changing the flow of single-phase liquid coolant to two-phase bubbly flow comprising a liquid coolant and a plurality of vapor bubbles dispersed within the liquid coolant, the plurality of vapor bubbles having a first number density;
• providing a second heat sink module mounted on a second heat-providing surface, the second heat sink module comprising a second inlet port and a second outlet port;
• and
• providing a first section of tubing having a first end connected to the first outlet port of the first heat sink module and a second end connected to the second inlet port of the second heat sink module, wherein the first section of tubing transports the two-phase bubbly flow having the first number density from the first outlet port of the first heat sink module to the second inlet port of the second heat sink module;
• and
• projecting the two-phase bubbly flow having the first number density against the second heat-providing surface within the second heat sink module, wherein a second amount of heat is transferred from the second heat-providing surface to the two-phase bubbly flow having a first number density and thereby changing two-phase bubbly flow having a first number density to a two-phase bubbly flow having a second number density greater than the first number density,
• wherein the predetermined temperature of the flow of single-phase liquid coolant at the first inlet port of the first heat sink module is about 0.5-20, 0.5-15, 0.5-10, 0.5-7, 0.5-5, 0.5-3, 0.5-1, 1-20, 1-15, 1-10, 1-7, 1-5, 1-3, 3-20, 3-15, 3-10, 3-7, 3-5, 5-20, 5-15, 5-10, 5-7, 7-20, 7-15, 7-10, 10-20, 10-15, or 15-20 degrees C. below the saturation temperature of the flow of single-phase liquid coolant at the predetermined pressure of the flow of single-phase liquid coolant at the first inlet of the first heat sink module.

A method of cooling two heat-providing surfaces within a server using a cooling apparatus comprising two series-connected heat sink modules, the method comprising:

• providing a flow of single-phase liquid coolant to an inlet port of a first heat sink module mounted on a first heat-providing surface within a server, wherein a first amount of heat is transferred from the first heat-providing surface to the single-phase liquid coolant resulting in vaporization of a portion of the single-phase liquid coolant thereby changing the flow of single-phase liquid coolant to two-phase bubbly flow comprising liquid coolant with vapor coolant dispersed as bubbles in the liquid coolant, the two-phase bubbly flow having a first quality;
• and
• transporting the two-phase bubbly flow from an outlet port of the first heat sink module to an inlet port of a second heat sink module, wherein the second heat sink module is mounted on a second heat-providing surface within the server, wherein a second amount of heat is transferred from the second heat-providing surface to the two-phase bubbly flow resulting in vaporization of a portion of the liquid coolant within the two-phase bubbly flow thereby resulting in a change from the first quality to a second quality, the second quality being higher than the first quality,
• wherein energy from the first amount of heat and the second amount of heat are stored, at least in part, as latent heat in the two-phase bubbly flow and transported out of the server through the cooling apparatus,
• wherein a saturation temperature and pressure of the two-phase flow having a second quality is less than a saturation temperature and pressure of the two phase flow having a first quality, thereby allowing the second heat-providing surface to be maintained at a lower temperature than the first heat-providing surface when a first heat flux from the first heat-providing surface is approximately equal to a second heat flux from the second heat-providing surface.