Adsorption heat exchanger devices
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Solution Overview
Problem
Solid sorption refrigeration systems have low cooling power due to poor heat transfer characteristics of adsorbent materials, particularly due to hindered vapor flow and slow adaptation of vapor pressure to system pressure changes, resulting in limited cooling and regeneration rates.
Innovation Solution
A method involving a highly-dilute curable binder solution applied to granular adsorbent material, forming localized bonds around contact points during evaporation and curing, which enhances thermal conductivity and mechanical stability without impeding mass transport, and can be applied to heat exchanger structures for improved adsorption heat exchanger devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If consolidated adsorbent materials are used to improve thermal conductivity, then heat transfer is improved, but permeability to adsorbate vapor deteriorates
Solution Approach 1:
The binder is applied in a highly-dilute solution (1-10% concentration) so that it forms localized bonds only at contact points between granules rather than coating the entire surface. This localized application provides thermal conductivity improvement at interfaces while leaving the majority of the granule surface porous and accessible to vapor.
Solution Approach 2:
The adsorbent structure becomes a composite of adsorbent granules bound by a cured binder matrix. The binder provides thermal conductivity and mechanical strength, while the porous nature of the granules and the dilute application method preserve vapor permeability pathways through the structure.
2Productivity
If granular adsorbent material is used to maintain vapor permeability, then mass transport is improved, but thermal conductivity deteriorates
Solution Approach 1:
The binder acts as an intermediary substance at the contact points between granules, providing a thermally conductive pathway for heat transfer while not obstructing the vapor flow pathways that pass through the porous structure of the granules themselves.
3Temperature
If adsorbent material is coated on heat exchanger surface to improve thermal interface, then heat transfer is improved, but vapor access to adsorbent deteriorates
Solution Approach 1:
The binder is applied in a highly-dilute solution so that it forms localized bonds only at contact points between granules rather than coating the entire surface. This localized application provides thermal conductivity improvement at interfaces while leaving the majority of the granule surface porous and accessible to vapor.
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 approach results in efficient adsorbent structures with improved thermal conductivity and mechanical stability, enhancing the specific cooling power of solid sorption refrigeration systems by expanding thermal interfaces and maintaining vapor transport efficiency.
Implementation Method 1
evaporating the solvent
Implementation Method 2
curing the binder
Implementation Method 3
the refrigerant vapor is adsorbed by the adsorbent substance resulting in release of heat
Implementation Method 4
heat is applied to the adsorbent causing desorption of the refrigerant
Implementation Method 5
The heat transferred during these processes is conveyed by a heat exchanger between the adsorbent and a heat transfer fluid
Implementation Method 6
evaporation of the liquid refrigerant in the evaporator. During this evaporation, heat is extracted from an environment to be cooled
Implementation Method 7
The now gaseous adsorbate passes to a condenser where heat rejection to the environment takes place
Data Source
AI summary
Adsorption heat exchanger devices (11, 25) are provided for use in solid sorption refrigeration systems (1) together with methods for making such devices and adsorbent structures therefor. The methods include applying a curable binder, in solution in a solvent, to granular adsorbent material, and then evaporating the solvent and curing the binder. The curable binder solution is sufficiently dilute that, during evaporation of the solvent, the binder becomes concentrated around contact points between granules (18) of the adsorbent material whereby localized bonds (19) are formed around the contact points on curing of the binder.