Design and Fabrication of IoT Based Parabolic Solar Dryer with Phase Change Material for Enhanced Thermal Energy Storage

Abstract

Designing and fabrication of an indirect solar dryer that integrates phase change material (PCM) into a parabolic solar collector. The system aims to increase thermal efficiency and enable nighttime drying. Because of its high latent heat storage capacity, the PCM, which is paraffin wax, stores excess thermal energy during the hottest hours of the day and releases it at night. This cost-effective technique encourages sustainable drying solutions and reduces dependency on fossil fuels by optimising energy use. System performance can be monitored by Blynk app to track the humidity and temperature of the drying chamber in real time. The test results show how well the solar dryer uses solar energy to maximise drying, with a noticeable decrease in moisture as the temperature rises.This solar dyer is very easy to use and offers farmers in developing countries a sustainable method of lowering post-harvest losses.

Introduction

A. Project Purpose

This project aims to develop a sustainable, efficient, and IoT-enabled solar drying system for agricultural products. It combines:

• Parabolic Trough Collectors (PTCs) to concentrate solar energy,

• Phase Change Material (Paraffin Wax) to store thermal energy for night use,

• And real-time temperature/humidity monitoring via the Blynk app.

This enhances drying efficiency, reduces post-harvest losses, ensures better product quality, and enables 24-hour drying capability.

B. Key Objectives

• Use IoT sensors for real-time temperature and humidity monitoring.

• Enhance system efficiency with PCM thermal storage.

• Maintain optimal drying conditions for product quality.

• Provide remote access and monitoring via Blynk.

• Improve operational safety and analyze performance data.

C. Literature Survey Summary

1. Existing Solar Dryers: PCMs improve temperature regulation and thermal efficiency (10–15%).

2. PCM Integration: Studies show significant improvements in thermal performance (up to 42%) and exergy efficiency (up to 31%) with paraffin wax.

3. PTC with PCM: Combining PCM with PTC enhances output temperature and ensures longer heat retention (e.g., in solar desalination or greenhouse drying).

4. Tilt Angle Effects: Optimal angles (7°–33°) improve solar energy capture and thermal efficiency (up to 73%).

5. Blower Systems: CFD and proper blower selection improve airflow, reduce energy waste, and extend component life.

6. Temperature & Humidity Monitoring: Arduino and Bluetooth-based systems provide accurate, real-time environmental tracking, replacing outdated manual logging.

D. Methodology & System Design

1. Materials Used

• Polycarbonate acrylic sheets: Durable and transparent chamber material.

• Parabolic Collector: Concentrates solar radiation on absorber tube.

• Paraffin Wax: Stores heat energy during the day (latent heat: ~200 kJ/kg).

• Blower: Circulates hot air.

• Absorber Tube: Transfers heat to air via copper piping.

• Wire Mesh Tray: Holds agricultural produce inside the drying chamber.

• NodeMCU + DHT11 Sensor: Captures and transmits environmental data.

• Blynk App: Displays live temperature/humidity on user’s phone.

2. Working Principle

• Solar energy is concentrated by the PTC onto the copper absorber tube.

• Air is heated as it passes through the tube, aided by the blower.

• The PCM stores excess heat during peak sun hours and releases it at night, enabling continuous drying.

• The IoT system (NodeMCU + DHT11) monitors drying conditions and transmits data to the Blynk app, allowing real-time remote control.

3. Theoretical Calculations

• Solar Energy Collected:
  Q = 800 W/m² × 0.36 m² = 288 W

• Air Mass Flow Rate (for 35°C rise):
  m = Q / (cp × ΔT) = 288 / (1.005 × 35) ≈ 0.008 kg/s

• PCM Heat Storage Capacity:
  Q_PCM = 7 kg × 200 kJ/kg = 1400 kJ

4. System Specifications

• Collector Diameter: 450 mm

• Length: 800 mm

• Drying Chamber: 450 mm × 250 mm × 500 mm

• PCM Used: Paraffin Wax

• Reflector Material: Aluminum

E. Programming

The ESP8266 microcontroller collects and transmits data from the DHT11 sensor to the Blynk mobile app. Real-time temperature and humidity values are logged and displayed, enabling remote monitoring and control.

F. Results & Benefits

• Efficient drying during day and night due to PCM.

• Improved product quality through stable temperature and humidity.

• Reduced energy usage and drying time.

• Remote monitoring and control, enhancing user experience.

• Potential for scalability and adaptation in rural agricultural practices.

Conclusion

A Parabolic solar dryer design has been successfully developed and tested, demonstrating its ability to effectively dry agricultural products while minimizing moisture content This system is easier to replicate globally and requires less maintenance than traditional open sun drying. Its novel integration of a parabolic collector, phase change materials (PCM), and Internet of Things (IoT)-based monitoring allows for optimal drying conditions, accurate temperature and humidity control, and effective solar energy harvesting. This environmentally friendly design improves product quality, drying effectiveness, and thermal storage, making it a desirable option for agricultural applications.

References

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Copyright

Copyright © 2025 Kishore C V, Pavithra S, Mude Poorna, Anu Freeda M, Seetharam P G, Monika K. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.