Uniform heat distribution, low cost, and abundant availability

Researchers from India’s National Institute of Technology (NIT) Kurukshetra and the National Institute of Solar Energy (NISE) Gurugram have developed a PV-powered Fine Sand Solar Geyser (FSG) system for domestic hot water applications. The system uses fine sand as a thermal storage medium, leveraging its high thermal mass, excellent heat retention, uniform heat distribution, low cost, and abundant availability. Electricity generated by three 300 W polycrystalline solar panels powers a nichrome wire heating rod, which converts electrical energy into heat stored in 120 kg of fine sand. A circular heat exchanger with aluminum fins transfers the stored heat to water passing through embedded pipes. The system demonstrated high thermal storage efficiencies of 97.41% and 90.76% over two days, delivering 140–152 liters of hot water daily at an average temperature difference of 11.7–13.75°C. With an initial capital cost of $278, an energy cost of $0.0233 per kWh, and a lifespan of 25 years, the FSG is described as a cost-effective, sustainable, and environmentally friendly solution for domestic water heating.

System Components:

1. Solar Panels:

   • Three 300 W polycrystalline solar panels generating electricity.

2. Heating Element:

   • Nichrome wire heating rod converting electrical energy into heat.

3. Thermal Storage Medium:

   • 120 kg of fine sand chosen for its high thermal mass, excellent heat retention, uniform heat distribution, low cost, and abundance.

4. Heat Exchanger:

   • Circular heat exchanger with aluminum fins transferring stored heat to water passing through embedded pipes.

Performance Metrics:

1. Sand Temperature Increase:

   • Day 1: Increased from 25.2°C to 164.2°C.

   • Day 2: Increased from 94.7°C to 211.9°C.

2. Thermal Energy Stored:

   • Day 1: 14.39 MJ.

   • Day 2: 13.02 MJ.

3. Thermal Storage Efficiency:

   • Day 1: 97.41%.

   • Day 2: 90.76%.

4. Hot Water Output:

   • Day 1: 140 liters.

   • Day 2: 152 liters.

5. Water Temperature Difference (Inlet vs. Outlet):

   • Day 1: 11.7°C.

   • Day 2: 13.75°C.

6. Discharging Efficiency:

   • Approximately 90% on both days.

Economic Analysis:

1. Initial Capital Cost:

   • $278.

2. Energy Cost:

   • $0.0233 per kWh.

3. Lifespan:

   • 25 years.

4. Payback Period:

   • 4.45 years.

Key Features and Benefits:

1. Sustainability:

   • Uses renewable solar energy and eliminates reliance on conventional fossil fuel-based water heating systems.

2. Cost-Effectiveness:

   • Low initial capital cost and energy cost ($0.0233/kWh) make it economically viable for domestic use.

3. Environmental Impact:

   • Reduces carbon emissions by replacing traditional water heaters with a renewable energy-based solution.

4. Overcoming Intermittency:

   • Fine sand acts as an efficient thermal storage medium, addressing the intermittency of solar radiation.

5. Scalability:

   • Simple design and abundant materials make it suitable for widespread adoption in rural and urban areas.

Applications:

1. Domestic Hot Water:

   • Provides reliable and affordable hot water for households, particularly in regions with abundant sunlight.

2. Rural Areas:

   • Offers an accessible solution for communities without access to conventional energy infrastructure.

3. Sustainable Development:

   • Supports global efforts to transition to renewable energy and reduce greenhouse gas emissions.

Research Context:

1. Publication Details:

   • Paper Title: “Thermal performance analysis of a fine sand solar geyser integrated with photovoltaic technology”.

   • Published in: Energy Sources.

2. Research Team Insights:

   • Dinesh Kumar Saini: Emphasized the system’s sustainability, cost-effectiveness, and ability to overcome solar intermittency.

   • Chandrashekara Muniyappa: Highlighted the system’s efficiency and economic viability for domestic water heating applications.

This detailed breakdown highlights the innovative design, performance metrics, and economic viability of the Fine Sand Solar Geyser (FSG), showcasing its potential as a sustainable solution for domestic water heating.