Vacuum Cooling System Using Aqueous Ammonia to Reduce Pump Complexity
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Solution Overview
Problem
Existing vacuum cooling systems for air-conditioning face challenges in maintaining a high vacuum continuously and are hindered by the expense and maintenance issues related to complex and expensive liquid ring or rotary vane pumps, which are not designed for continuous use and fail with water vapor in their gas streams.
Innovation Solution
A vacuum cooling system utilizing a first fluid with a higher volatile component, such as aqueous ammonia, circulating through separate cycles, where the fluid is evaporated in a vacuum chamber, and the gas is removed by a pump to create a vacuum, with a heat exchanger cooling a secondary fluid to cool the air, and a baffle preventing liquid droplets from entering the pump, allowing efficient cooling with simpler and less expensive pump designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid ring or rotary vane pumps are used to create high vacuum for cooling, then the cooling temperature can reach freezing point, but the pump complexity and maintenance cost increase significantly
Solution Approach 1:
A baffle plate is introduced as an intermediary component between the vacuum chamber and the pump inlet. This baffle prevents liquid droplets from reaching the pump while allowing vapor to pass through, thereby protecting simple pump designs from damage and eliminating the need for complex liquid ring or rotary vane pumps
Solution Approach 2:
The harmful liquid droplets are separated and removed from the vapor stream using a baffle plate before entering the pump. This extraction of the problematic component allows the use of simpler, more reliable pump designs that would otherwise be damaged by liquid contamination
2Device complexity
If water is used as refrigerant with low latent heat of vaporization, then the system is simple, but large volume of gas must pass through heat exchanger resulting in high compressor energy consumption
Solution Approach 1:
The system changes the physical parameter of the refrigerant by using aqueous ammonia instead of pure water. Ammonia has a much higher latent heat of vaporization (2260 kJ/kg vs 216.97 kJ/kg for R-134A), which increases the cooling efficiency and reduces the volume of gas that needs to be compressed, thereby lowering energy consumption
Solution Approach 2:
The invention uses a composite refrigerant system with aqueous ammonia (ammonia dissolved in water) as the working fluid. This composite approach combines the high latent heat of ammonia with the availability and safety of water-based systems, achieving both high efficiency and practical operability
3Productivity
If aqueous ammonia is evaporated in vacuum chamber, then high cooling efficiency is achieved with high latent heat of vaporization, but liquid droplets may enter the pump causing damage
Solution Approach 1:
A baffle plate is positioned in the vacuum chamber to act as an intermediary barrier. It allows ammonia vapor to pass through and be pumped away while blocking liquid droplets from reaching the pump inlet, thus protecting the pump from liquid damage while maintaining high cooling efficiency
Solution Approach 2:
The potential harm of liquid droplet carryover is converted into a design feature by using the baffle plate to separate phases. The liquid droplets that would otherwise damage the pump are instead redirected to return to the evaporator, where they can be re-evaporated, turning a potential failure mode into a self-correcting feature
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
This system achieves efficient cooling with reduced energy consumption and lower maintenance costs, as it uses aqueous ammonia with a high latent heat of vaporization, allowing for scalable solutions from small rooms to large commercial spaces with improved Coefficient of Performance (COP) compared to conventional air-conditioners.
Implementation Method 1
a volume of gas evaporated from said first fluid portion
Implementation Method 2
uses aqueous ammonia with a high latent heat of vaporization
Implementation Method 3
first pump means for removing the gas volume from the vacuum chamber to create a vacuum in said vacuum chamber
Implementation Method 4
heat exchanger means for cooling said second fluid over which air is blown in order to cool the air in a space
Data Source
AI summary
A vacuum cooling system (10) having a first fluid (21) and a second fluid (70) circulating through the system (10) in separate cycles, said system (10) including a vacuum chamber (1) containing a portion (14) of said first fluid and a volume of gas (42) evaporated from said first fluid portion (14), a first pump means (7) for removing the gas volume (42) from the vacuum chamber (1) to create a vacuum in said vacuum chamber (1), a means for moving (8) said first fluid (21) into said vacuum chamber (1) to replenish the first fluid portion (14) in said vacuum chamber (1), and heat exchanger means (2) for cooling said second fluid (70) over which air is blown in order to cool air in a space.