What is it about?
This research explores a solar-powered device that makes ice without electricity, ideal for remote areas in hot climates where power is scarce. It uses a chemical reaction between barium chloride (a salt) and ammonia (a gas) in a "thermochemical refrigerator." Sunlight heats flat solar panels during the day to separate the chemicals, releasing ammonia, which condenses into liquid. At night, they recombine, pulling heat from water to freeze it into ice at -5°C to -10°C (23°F to 14°F). The team did math calculations to analyze the system's efficiency (COP, or cooling per heat input, stable at 0.1-0.3) and ran year-long computer simulations for tropical conditions, figuring out how much solar panel area is needed (optimal around 0.75 solar fraction for cost-effectiveness) and monthly performance variations. Unlike traditional fridges that need constant power or complex setups, this runs on simple, cheap collectors, uses air or water for cooling, and avoids high temperatures over 70°C. It's like a sun-charged battery for cold, potentially preserving food, medicine, or vaccines in off-grid villages, with predictions for real-world use in places like Latin America.
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Why is it important?
In 2025, with climate change amplifying heatwaves and over 600 million people still off-grid, this 2001 study is vital for sustainable cooling in rural tropics, where food loss exceeds 30% due to spoilage. Unique aspects include the BaCl2/NH3 pair's low-heat requirement (under 70°C from basic flat collectors, vs. 100°C+ for others), stable COP under varying conditions, and air-cooling option in water-scarce areas—reducing reliance on electricity or fuels. It could slash costs for ice production (5-10 kg/m²/day), boost economic development by enabling perishable goods storage, and cut emissions by harnessing abundant solar resources. With 25 citations, it has shaped sorption tech advancements, inspiring efficient prototypes for global challenges like vaccine cold chains or agriculture in Africa and Asia, promoting equity and eco-friendly innovation.
Perspectives
This paper in Solar Energy Materials & Solar Cells presents a thermodynamic analysis and dynamic simulation of an intermittent solar thermochemical refrigeration system using BaCl2/NH3 for ice production, with the objective on rural and electricity-deficient regions. The reversible reaction BaCl2(s) + 8NH3(g) ⇌ BaCl2·8NH3(s) has ΔH = -23.33 kJ/mol NH3, with equilibrium vapor pressure log P = 23.05 - 4720/T (P in Pa, T in K). The requirement would be a flat-plate solar collector (irradiance close to 4-6 kWh/m²/day), dissociation at 52-58°C for condensation at 35-40°C, evaporation at -5 to -10°C, yielding absorption at 25-28°C to the surroundings (typical in tropical regions).
Professor Rosenberg J Romero
Universidad Autonoma del Estado de Morelos
Read the Original
This page is a summary of: Dynamic study of the thermal behaviour of solar thermochemical refrigerator: barium chloride-ammonia for ice production, Solar Energy Materials and Solar Cells, December 2001, Elsevier,
DOI: 10.1016/s0927-0248(01)00081-2.
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