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Cold Enough Cascade Planning Stage

04.07.08 - 05:14am

I have decided to embark upon what will most likely be a lengthy but carefully planned cascade build. This will become my primary benching and reviewing cascade to replace my underpowered but otherwise ideal Baby cascade. I am aiming at -95C loaded temperatures, cold enough to consistently bench at 5200MHz and higher but not cold enough to cold bug the processors I’ll be using. This is simply the planning stage, there will likely be another post detailing the construction, and a last post detailing initial results.

How Cascades Operate

Cascades are simply highly specialized refrigeration systems. This particular cascade will use R507 which boils at -46.7 Celsius at 0 psi to cool a secondary charge of R1150 which boils at -103.7 Celsius at 0 psi. The system utilizes two compressors and a inter-stage heat exchanger that lets the liquid R507 to evaporator and cool the gaseous R1150. The gaseous R1150 will condense into a liquid that can be evaporated inside of the evaporator attached to the CPU. To call the system simple would be an understatement but in the world of nearly cryogenic refrigeration, an R507/R1150 cascade is rather simple.

Features

Last week I spent two days working on repairing and retuning a 3 stage cascade for a friend. In working on the cascade I realized there were a few features that I’d like to incorporate into the Cold Enough Cascade to avoid issues that presented themselves in the 3 stage cascade. The 45nm Core 2 Quad processors have issues booting up at temperatures below -60C, much warmer than the evaporator temperatures I am aiming for. To keep from freezing the processor at -95C, I will incorporate special electronic valves that will let me cut refrigerant flow to the evaporator and thereby let the evaporator stay at a specific temperature for a short duration of time. Other features will include specialized heat exchangers to keep from choking the 2nd stage compressor and also oil return valves so the coldest temps can be realized. I will include a resistor on the backside of the evaporator so to let me warm the evaporator up to ambient temperatures when dismounting and I will also line the suction line with a heating element to help warm up the cold steel and to prevent snapping the line.

Ease of Use

Usability will be a big factor with this cascade. I will have a single panel that will have all the pressure monitoring gauges, temperature gauges, solenoid switches, safety switches, and main power switches. I’d like to make this cascade remotely controllable so the user doesn’t have to touch the cascade itself but rather interface with it via this control panel. This will help remove user manipulation from damaging valves and keep the user from having to touch high voltage components.

Safety

Safety will be another large factor into the design of this cascade. There will be electrical cut-offs at 300 psi and 350 psi. The first cut-off will serve to open both solenoid valves to ease pressure between the discharge and suction sides of the 2nd stage. The 350 psi cut-off will cut all power to the unit in case there is either a clog or the 1st stage had died. There will then be a 425 psi burst valve that will vent the R1150 charge in case of fire or an other catastrophe. All components will be grounded and all high-voltage electronics will be properly sleeved.

Final Notes

I plan on having this unit finished by late April. It will feature twin 1 horse power rotary compressors, a Temprite 304A oil separator, a 12 plate heat exchanger, a 5 foot suction line, and a Chilly1 spiral evaporator. I imagine I will have all the necessary components within 7 days, expect a construction post in roughly 14 days.

Category: Articles, How To, Phase Cooling, Phase Cooling Custom Builds