Open Absorption Cycle With Thin-Film LiBr Heat and Humidity Control
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Solution Overview
Problem
Vapor compression systems consume significant electrical energy and use non-environmentally friendly refrigerants, while absorption refrigeration systems are inefficient in utilizing low-grade thermal energy for cooling and heating, necessitating the development of more energy-efficient technologies that can also handle increasing demand in developing countries.
Innovation Solution
An open absorption cycle system utilizing ultra-thin film absorbers and desorbers with a lithium bromide-water based cycle, where water vapor is absorbed and desorbed to provide dehumidification, water heating, and evaporative cooling, with the energy released during phase transition used to heat the process fluid, and the condensed water vapor used for cooling or drained for dehumidification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If vapor compression systems are used for cooling and heating, then cooling and heating functions are provided, but significant electrical energy is consumed and non-environmentally friendly refrigerants are used
Solution Approach 1:
The patent replaces the mechanical vapor compression system with a thermal absorption system that uses lithium bromide solution to absorb and release water vapor. This substitution eliminates the need for electrical compressors and environmentally harmful refrigerants, using instead a natural absorption-desorption cycle driven by thermal energy.
Solution Approach 2:
The system utilizes phase transitions of water between liquid and vapor states in the absorption and desorption processes. Water vapor is absorbed by the lithium bromide solution in the absorber and then desorbed from the solution in the desorber, leveraging phase change to provide cooling and heating functions without mechanical compression.
2Temperature
If conventional absorbers and desorbers are used in LiBr-water ARSs, then water heating and dehumidification are provided, but the systems are large and inefficient in utilizing low-grade thermal energy
Solution Approach 1:
The patent employs thin film configurations for both the absorber and desorber heat exchangers. The thin film geometry dramatically increases the surface area to volume ratio, enabling efficient heat and mass transfer with low-grade thermal energy while reducing the overall size of the heat exchangers compared to conventional bulk systems.
Solution Approach 2:
The system changes the geometric parameters of the heat exchangers from conventional bulk structures to thin film structures. This parameter change increases the effective heat transfer surface area while reducing the volume required, thereby improving efficiency in utilizing low-grade thermal energy and reducing system size.
3Temperature
If falling film desorbers are used with low temperature heat sources, then water desorption is facilitated, but the system complexity increases
Solution Approach 1:
The patent merges the absorber and desorber functions into a unified system architecture where both operations are performed using thin film configurations. This integration simplifies the overall system by using consistent design principles for both heat exchangers and enabling efficient coupling between the absorption and desorption processes.
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 system achieves efficient water heating, dehumidification, and cooling with a thermal coefficient of performance (COP) of 1.6, significantly improving energy efficiency and reducing external heat input, while allowing for compact and cost-effective implementation.
Implementation Method 1
Ambient water vapor absorbs into a lithium bromide solution, which dehumidifies the ambient air. The energy released by the absorption of the ambient water vapor in the absorber due to the phase transition is used to heat the process fluid.
Implementation Method 2
The lithium bromide solution is regenerated in the desorber by providing sufficient heat to the solution.
Implementation Method 3
The desorbed water vapor is then condensed in the condenser where the condensation of water vapor in the condenser heats the process fluid
Implementation Method 4
The condensed water vapor is either drained from the system to provide exclusively dehumidification at the absorber or is sprayed into an air stream to provide evaporative cooling of the air stream
Data Source
AI summary
An absorption cycle system, which permits water heating, dehumidifying, and/or evaporative cooling, includes a desorber, absorber, heat exchanger, and, optionally, an evaporator, is constructed to heat a process water that is plumbed through the absorber, heat exchanger, and condenser. In the absence or isolation of the evaporator, the system can dehumidify ambient air to the absorber. The water vapor released by evaporative cooling at the evaporator can be provided to the absorber in a controlled manner to simultaneously maintain a desired humidity while cooling the air ambient by the evaporator. The absorption cycle system can be housed within a single unit or can be compartmentalized.