Buffered heat transfer fluid for secondary refrigeration systems comprising a formate salt
AssigneeThe Lubrizol Corporation
InventorsGilbert R. Malone, Stephen H. Stoldt
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Abstract
A formate salt based heat transfer fluid having a pH containing a phosphate for a secondary refrigeration loop is disclosed. The formate based heat transfer fluid generally is a more effective heat transfer medium than a glycol based fluid designed to operate in the same temperature range. The formate based fluid also has lower toxicity and environmental risks than the glycol fluid.
Claims14
In a heat pump system comprising of
- a) a primary refrigerant contained in a compression or absorption refrigeration equipment to pump heat between a target and heat sink (towards or from) and
- b) a potassium and/or sodium salt of formic acid in water used as heat transfer fluid to transport heat away from or towards said refrigeration equipment, the improvement comprising including an alkali nitrite;
- 0.1 wt. % or more of a buffer component having a pH as a 1 wt. % solution in water above 10, selected from alkali metal borate, alkali metal carbonates, and alkali metal phosphates;
- and from at least 0.01 weight percent sulfamic acid based on the weight of said heat transfer fluid for said heat transfer fluid.
A method for providing cooling and/or heating comprising;
- a) passing a primary refrigerant through a refrigeration cycle to transfer heat from the evaporator side to the condenser side,
- b) contacting a heat transfer fluid with said evaporator side or said condenser side of said refrigeration cycle and thereby cooling or heating said heat transfer fluid,
- c) pumping said heat transfer fluid from said evaporator or condenser side to another location and transferring heat from between said location and said heat transfer fluid, and
- d) pumping said heat transfer fluid from step c back to said evaporator or condenser side of said refrigeration cycle,
- wherein the improvement comprises said heat transfer fluid comprising 15 to 75 wt. % of formic acid salt;
- an alkali nitrite;
- 0.1 wt. % or more of a buffer component having a pH as a 1% solution in water above 10, selected from alkali metal borate, alkali metal carbonates, and alkali metal phosphates;
- and from at least 0.01 weight percent sulfamic acid based on the weight of said heat transfer fluid.
A heat transfer composition comprising water, potassium formate, an alkali nitrite, sulfamic acid, and 0.1 wt. % or more of a buffer component having a pH as a 1% solution in water above 10, selected from alkali metal borate, alkali metal carbonates, and alkali metal phosphates based on the weight of said heat transfer fluid.
Dependencies are inferred from the claim text.