Jet-Based Sorbent Distribution for Sub-Zero Absorption Heat Pumps
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Solution Overview
Problem
Existing absorption chillers and heat pumps face limitations in efficiency and applicability at ambient temperatures below 0°C due to high viscosity and low thermal conductivity of ionic liquids, leading to poor heat and mass transfer densities compared to aqueous lithium bromide solutions.
Innovation Solution
A device with a jet device that disperses the sorption agent or refrigerant as jets onto the heat exchange surface, generating turbulent flows to enhance absorption and desorption, overcoming the limitations of high viscosity and low thermal conductivity by improving heat and material transport densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ionic liquids are used as absorption agent, then the system can operate at temperatures below 0°C, but the high viscosity and low thermal conductivity result in poor heat and mass transfer densities
Solution Approach 1:
The patent applies dynamic jet injection to transform the static absorption process into a dynamic one. The absorption agent is injected as high-velocity jets that create turbulent mixing and enhance mass transfer. This dynamic approach overcomes the inherent high viscosity of ionic liquids by using kinetic energy to drive mixing rather than relying on natural convection or diffusion, thereby achieving high heat and mass transfer densities at sub-zero temperatures.
Solution Approach 2:
The patent changes the physical state and flow parameters of the absorption agent by injecting it as high-velocity jets rather than allowing it to flow slowly. This parameter change from static/diffusive transport to dynamic/jet-driven transport fundamentally alters the heat and mass transfer characteristics, enabling ionic liquids to achieve high transfer densities despite their high viscosity and low thermal conductivity.
2Productivity
If aqueous lithium bromide solution is used, then high heat and mass transfer densities are achieved, but the system cannot operate efficiently at temperatures below 0°C
Solution Approach 1:
The patent uses composite approach by combining ionic liquids (which enable sub-zero operation) with jet injection technology (which provides high transfer densities). This composite solution integrates the temperature advantage of ionic liquids with the transfer efficiency advantage of jet-driven flow, achieving both low-temperature operation and high productivity that neither approach could achieve alone.
3Ease of operation
If sprinkling method is used to dispense absorption agent, then a stationary film forms on heat exchange surface, but heat and mass transfer densities remain low
Solution Approach 1:
The patent replaces the static sprinkling method that creates stationary films with dynamic jet injection that creates moving, turbulent flows. The high-velocity jets continuously renew the absorption agent contact with the heat exchange surface, preventing film stagnation and maintaining high transfer rates. This dynamic approach transforms the simple but inefficient sprinkling method into a high-performance dispensing system.
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 proposed solution enables efficient absorption and desorption at temperatures below 0°C, achieving heat and material transport densities comparable to aqueous lithium bromide solutions, and allows for the use of ethanol as a refrigerant with ionic liquids, enabling efficient operation of absorption heat pumps in cold conditions.
Implementation Method 1
generate turbulent flows of the sorption agent on the heat exchange surface
Implementation Method 2
the sorption agent absorbs a refrigerant, for example water or ammonia, which is introduced into the area of the heat exchange surface as a vaporous medium
Implementation Method 3
Heat of absorption arises during the absorption of the refrigerant, which can be emitted to a cooling medium in the heat exchanger
Data Source
AI summary
A device is presented for an absorption refrigerator or an absorption heat pump having a heat exchanger through which a working medium flows. The device includes a distribution apparatus for a sorbent which is designed to apply the sorbent to a heat exchange surface of the heat exchanger in a refrigerant environment such that the sorbent, which forms a working pair with the refrigerant, at least partially absorbs the refrigerant from the refrigerant environment and emits heat released in the process to the heat exchanger, or at least partially desorbs the refrigerant from the sorbent in the form of one or more jets onto the heat exchange surface, forming turbulent flows of the sorbent on the heat exchange surface.