Goal
Provide solar-driven cooling that operates in phase with solar insolation, especially for off-grid or rural applications.
Problem
Lack of electricity for conventional refrigeration and the mismatch between cooling demand and solar heat availability.
Concept Summary
A solar-thermal driven adsorption refrigeration cycle that operates intermittently (diurnal on/off) using a low-temperature heat source (flat-plate collector). The system adsorbs a refrigerant (e.g., water, ammonia, or NH_3) onto a sorbent (zeolite, CaCl_2, activated carbon), stores the heat-generated refrigerant, and releases it during the night to produce cooling.
Principles
- Adsorption-desorption thermodynamic cycle
- Intermittent (diurnal) operation
- Solar thermal energy collection
Scientific Domains
Materials
- Water (refrigerant)
- Ammonia (refrigerant)
- Zeolite (adsorber)
- Calcium chloride (CaCl_2) (absorbent)
- Activated carbon (adsorbent)
- Steel tube/plate
- Aluminium tube/plate
Mechanisms of Action
- Heat-driven desorption of refrigerant from sorbent
- Condensation of refrigerant in evaporator
- Heat pipe recovery between absorber and condenser
Energy Sources
Applications
- Rural refrigeration
- Vaccine storage in off-grid areas
- Domestic air-conditioning
- Cold-storage for small-scale agriculture
Claimed Performance
Coefficient of performance (COP) of 0.19 (19 %) reported for the prototype; other studies report COP ~= 0.073 after collector optimisation.
Experimental Evidence
Prototype built and tested in a laboratory rig; measured COP was 0.19, 2 % lower than design target. Multiple papers report experimental runs with ice yield and condensate production.
Replication Status
Prototype constructed and experimentally evaluated; no large-scale commercial deployment reported.
Limitations
- Low COP compared with conventional vapor-compression
- Performance strongly dependent on solar insolation and ambient temperature
- Temperature variation and occasional freezing of the cold room
- Limited long-term durability data for sorbents and sealed vacuum panels
