Buffered Formate Heat Transfer Fluid for Low-Toxicity Refrigeration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing heat transfer fluids, such as ethylene glycol and propylene glycol solutions, are toxic and have decreased thermal conductivity as concentration increases, posing environmental and health risks, and tend to cause metal corrosion.
Innovation Solution
A buffered heat transfer medium comprising a formate salt, such as potassium or sodium formate, with selected corrosion inhibitors and biocides is used to reduce freezing points and minimize corrosion, maintaining high pH levels and solubility, allowing for improved heat transfer and reduced toxicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ethylene glycol or propylene glycol solutions are used as heat transfer fluids, then the freezing point is reduced and the fluid remains pumpable at low temperatures, but the toxicity increases and thermal conductivity decreases as glycol concentration increases
Solution Approach 1:
The invention changes the chemical composition parameters by using formate salts (potassium formate, sodium formate) instead of glycols as the primary freezing point depressor. This substitution maintains the ability to reduce freezing points while eliminating the toxicity associated with glycol solutions. The formate salt concentration can be adjusted to achieve desired freezing points without the harmful effects of glycols.
2Temperature
If ethylene glycol or propylene glycol solutions are used as heat transfer fluids, then the freezing point is reduced, but the thermal conductivity decreases as glycol concentration increases
Solution Approach 1:
The invention changes the heat transfer fluid composition from glycol-based to formate salt-based, fundamentally altering the thermal properties. Formate salt solutions maintain higher thermal conductivity compared to glycol solutions at equivalent freezing point depression levels, thus improving heat transfer efficiency while achieving the same freezing point protection.
3Reliability
If conventional heat transfer fluids are used, then the system operates reliably, but metal corrosion occurs
Solution Approach 1:
The invention changes the pH parameters of the heat transfer fluid by using formate salts, which create a more alkaline environment that is less corrosive to metals. Additionally, the invention incorporates specific corrosion inhibitors (such as nitrites, phosphates, or carboxylic acid salts) that chemically protect metal surfaces, thereby maintaining system reliability while eliminating corrosion problems.
4Temperature
If glycol concentration is increased to reduce freezing point, then the fluid remains liquid at lower temperatures, but the viscosity increases and heat transfer efficiency decreases
Solution Approach 1:
The invention changes the fluid composition from high-concentration glycol to formate salt solutions, which maintain lower viscosity across the operating temperature range. This parameter change ensures that pumping requirements remain low and heat transfer efficiency is preserved even at freezing points below -40°C, as formate salts do not exhibit the same viscosity increase as glycols at equivalent concentrations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The formate-based heat transfer fluid exhibits better thermal conductivity and lower toxicity than glycol solutions, with reduced metal corrosion and the ability to remain fluid at low temperatures, making it suitable for secondary refrigeration loops and applications where primary refrigerants pose health or safety concerns.
Implementation Method 1
The heat transfer fluid disclosed herein includes a buffered formate salt of sodium or potassium which acts as an electrolyte to reduce the freezing point of the water used in the solution
Data Source
AI summary
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.