Absorption refrigeration machine
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Solution Overview
Problem
Conventional absorption refrigeration machines using LiBr solutions are corrosive due to oxygen presence, requiring closed systems and high-alloy stainless steels, limiting their operation and efficiency, and often result in incomplete wetting of heat transfer surfaces.
Innovation Solution
The design incorporates a modular system with vapor-permeable, liquid-tight membrane walls and frame elements made of plastic, allowing for an open absorption chiller configuration where the evaporator and absorber are housed together, eliminating the need for a desorber and condenser, and enabling the use of LiBr solutions without corrosion, with refrigerant and salt solution flowing in closed channels for improved heat and mass transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LiBr solutions are used in conventional absorption refrigeration machines, then heat transfer efficiency is improved, but corrosion occurs due to oxygen presence requiring closed systems and high-alloy stainless steels
Solution Approach 1:
The harmful oxygen is extracted from the system by operating in an open configuration where the evaporator and absorber are exposed to atmospheric pressure, eliminating the need for closed systems and expensive corrosion-resistant materials while maintaining heat transfer efficiency
Solution Approach 2:
A vapor-permeable, liquid-tight membrane is introduced as an intermediary between the LiBr solution and the external environment, allowing refrigerant vapor to pass while blocking oxygen and liquid, thus preventing corrosion while maintaining system performance
2Device complexity
If conventional horizontal tube bundle apparatus are used with perforated plates, then system structure is simplified, but uniform wetting of tubes is difficult to achieve requiring larger mass flows
Solution Approach 1:
The heat exchange surface is segmented into numerous small channels arranged in a modular plate structure, ensuring uniform distribution and complete wetting of the working fluid across all surfaces without requiring excessive mass flows
Solution Approach 2:
The system transitions from conventional horizontal tube bundles to a vertical plate channel structure, fundamentally changing the geometric arrangement to achieve superior wetting characteristics and heat transfer efficiency
3Reliability
If closed systems with separate housing for evaporator/absorber and desorber/condenser are used, then corrosion is prevented, but device complexity and cost increase
Solution Approach 1:
The evaporator and absorber are merged into a single integrated unit operating at atmospheric pressure, eliminating the need for separate pressurized housings and complex interconnections, thereby reducing device complexity while maintaining corrosion prevention through the vapor-permeable membrane
Solution Approach 2:
The system pressure parameter is changed from negative pressure (vacuum) to atmospheric pressure for the evaporator and absorber units, fundamentally altering the system configuration to eliminate corrosion risks without requiring expensive materials or complex closed-system design
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 configuration allows for efficient heat transfer, reduces corrosion risks, and enables the use of LiBr solutions in an open system, enhancing the operational flexibility and efficiency of absorption refrigeration machines by ensuring complete wetting of exchange surfaces with minimal oxygen exposure.
Implementation Method 1
the refrigerant channel on its side opposite the heat-conducting wall being separated from a vapor space by a vapor-permeable, liquid-tight membrane wall
Implementation Method 2
a heat-conducting, vapor-tight and liquid-tight wall
Implementation Method 3
an evaporator for evaporating a refrigerant while absorbing heat from a refrigerant circuit
Implementation Method 4
an absorber for absorbing the refrigerant vapor by the concentrated, low-refrigerant working substance pair
Data Source
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AI summary
The invention relates to an absorption refrigerant machine having an evaporator for evaporating a refrigerant while heat is absorbed from a coolant circuit and an absorber for absorbing the refrigerant vapor by means of the concentrated, low-refrigerant pair of working substances. Said absorption refrigerant machine is characterized in that the evaporator comprises at least one evaporating unit having a coolant channel, through which the coolant flows and which is bounded at least partially by a heat-conducting, vapor- and liquid-tight wall, and having at least one refrigerant channel, which is adjacent to the heat-conducting wall and which is loaded with the refrigerant and which is separated from a vapor chamber by a vapor-permeable, liquid-tight membrane wall on the side of the refrigerant channel facing the heat-conducting wall, and that the absorber comprises at least one absorption unit having a cooling-medium channel, through which a cooling medium flows and which is bounded at least partially by a heat-conducting, vapor- and liquid-tight wall, and having at least one absorption channel, which is adjacent to the heat-conducting wall and to which the concentrated, low-refrigerant pair of working substances is fed and which is loaded with refrigerant vapor from the vapor chamber by means of a vapor-permeable, liquid-tight membrane wall provided on the side of the absorption channel facing the heat-conducting wall.