Water Dispenser Utilizing Waste Heat Through Shell and Tube Condenser

🛠️ Project Type: B. Tech Final Year Minor Project
🎓 Institution: MIT Academy of Engineering, Alandi (D), Pune
📅 Academic Year: 2024–2025
🧑‍🤝‍🧑 Team Size: 4 Members
💡 Course: Refrigeration & Air Conditioning (PBL Project)

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🌍 Introduction

As the global demand for energy-efficient and eco-friendly technologies rises, utilizing waste heat recovery systems has become crucial in engineering innovation. This blog explores a unique and sustainable approach developed as part of our Final Year B.Tech project, where we designed a Water Dispenser that operates by utilizing waste heat from a shell and tube condenser typically used in refrigeration systems.

This system aims to reduce the energy footprint of traditional refrigeration setups by converting rejected heat into useful output, such as providing lukewarm water for human consumption or cleaning purposes.

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🧠 Project Motivation

Refrigeration systems typically reject a significant amount of heat to the surroundings through condensers. In most systems, this heat is wasted. Our goal was to capture this waste heat and utilize it to heat water without additional electrical energy, leading to:

• Reduced environmental impact 🌱

• Enhanced system efficiency ⚙️

• Sustainable utility applications 💧

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📐 System Design Overview

We used a Shell and Tube Condenser to recover waste heat from the refrigerant and integrated a water coil within the condenser shell to transfer heat to the water.

🔩 Key Components:

• Hermetically Sealed Compressor

• Expansion Valve

• Shell & Tube Condenser

• Capillary Tube

• R-134a Refrigerant

• Water Tank

• Copper Tubing

• Water Dispenser Nozzle

🔁 Working Principle

1. The refrigerant absorbs heat from the evaporator and becomes a high-pressure vapor.

2. This vapor passes through the shell and tube condenser, where it releases heat.

3. A water line (copper tube) runs coiled inside the shell, absorbing the heat.

4. Heated water is stored and dispensed through a tap for external use.

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🧪 Design Calculations

1. Heat Load of the Condenser (Q):

[ Q = m \cdot C_p \cdot \Delta T ]

Where:

• ( m ) = Mass flow rate of water (kg/s)

• ( C_p ) = Specific heat of water (4.18 kJ/kg·K)

• ( \Delta T ) = Temperature rise of water

2. Water Outlet Temperature:

Given

• Inlet Temp = 25°C

• Outlet Temp = ~45°C (achieved experimentally)

3. Refrigerant Parameters:

• Refrigerant: R-134a

• Condensation temperature: ~55°C

• Shell surface area designed to optimize contact and transfer

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🖼️ System Schematic

Figure: Piping and instrumentation diagram of the system.

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⚙️ Fabrication Process

• 📏 Designed shell and tube layout using copper and steel.

• 🔧 Coiled copper tubes inside the shell using bending tools.

• 🧊 Connected the refrigeration system and water loop.

• 🌡️ Insulated the setup for minimal thermal losses.

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📊 Experimental Results

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🧾 Benefits and Applications

✅ Benefits:

• Zero extra energy required for water heating.

• Compact integration with existing refrigeration systems.

• Environmentally friendly – promotes sustainable waste heat recovery.

🏢 Applications:

• Cold rooms with integrated hot water taps

• Public water dispensers

• Modular HVAC systems in offices

• Rural cooling and heating solutions

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🎯 Challenges Faced

• Ensuring optimal heat transfer without overheating water.

• Avoiding pressure drop and maintaining refrigerant flow.

• Balancing insulation vs. heat recovery time.

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📸 Project Photos

Figure: Final fabricated system ready for testing.

Figure: Shell and tube assembly with copper water coil.

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📚 Learnings and Takeaways

• Understanding the thermodynamics of condensation and heat exchange.

• Real-time experience in fabrication and instrumentation.

• Integration of theory into practical engineering solutions.

• Promoting sustainable design thinking in mechanical systems.

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🔮 Future Scope

• Integration of solar PV for powering compressor.

• Automation of temperature control using IoT sensors.

• Use of natural refrigerants like R-290 for environmental compliance.

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🏁 Conclusion

This project showcases how simple engineering modifications can lead to meaningful sustainable outcomes. By transforming waste heat into useful heat, we open the door for more efficient RAC systems with dual functionality. The solution aligns with global sustainability goals and provides a cost-effective innovation for both domestic and industrial sectors.

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🙌 Acknowledgments

We thank our project guide, faculty members of the Mechanical Engineering Department at MITAOE, and our batchmates for their continuous support and insights.

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💬 Got Questions?

If you're interested in sustainable heat recovery systems or working on a similar project, feel free to connect or drop your questions in the comments!

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