# The Mission In closed enclosures like acrylic boxes, heat often becomes trapped, causing temperatures to spike beyond safe limits. Simply adding a heater isn't enough; you need a dynamic system that can both generate and evacuate heat to maintain a delicate equilibrium. I engineered this **Thermal Chamber** to solve the problem of thermal instability. My objective was to create a stable environment using a PTC heater and an exhaust fan controlled by a single intelligent loop, ensuring the environment remains within a precise "Dead Zone" suitable for incubation.

Final Assembly of the Acrylic Thermal Chamber

The physical realization of the thermal chamber using transparent acrylic for visibility and insulation.

--- ## The Intelligence: Hysteresis Control Logic Instead of a simple ON/OFF thermostat that causes rapid, damaging relay switching (chattering), I implemented a **Hysteresis Algorithm**. This approach uses the system's history to prevent unnecessary oscillations and extend the lifespan of mechanical components. ### The Logic Flow: * **Heating Phase:** If T Less Then 26.5°C, the PTC Heater activates and the Fan remains OFF. * **The Dead Zone (Stability):** Between **26.5°C and 27.5°C**, the system enters a "Dead Zone" where all actuators are OFF to save energy. * **Cooling Phase:** If T More than 27.5°C, the Fan activates to evacuate excess heat.

The Hysteresis Control Logic flow designed to maintain stability and prevent relay chattering.

--- ## Hardware & Architecture The system utilizes an **ESP32** as the central brain, processing real-time sensor data while simultaneously hosting a web server for remote interaction. | Component | Specification | Role | | :--- | :--- | :--- | | **Microcontroller** | ESP32 DevKit V1 | Main Processor & Wi-Fi Web Server | | **Sensor** | DHT-11 | Temperature & Humidity Sensing | | **Heating** | PTC Heater 12V | Thermal Generation | | **Cooling** | Brushless DC Fan 12V | Heat Evacuation | | **Power** | LM2596 Step-Down | Voltage Regulation (12V to 5V) | | **Display** | LCD I2C 16x2 | Local Real-time Monitoring | --- ## 🌐 Real-Time IoT Dashboard I developed a custom **Web Dashboard** hosted directly on the ESP32 (IP `192.168.4.1`). This provides an essential layer of control that conventional thermostats lack. * **High Responsiveness:** Data updates with an average latency of **<200ms**. * **Manual Safety Override:** In emergency scenarios or sensor failures, I programmed the system so users can manually force the fan or heater ON/OFF via the web interface. * **Redundancy:** If the network fails, the physical LCD provides an immediate local backup for data monitoring.

The real-time dashboard showing current temperature and humidity with manual override controls.

--- ## Challenges & Engineering Evaluation Professional engineering requires the courage to analyze failures. During the final demonstration, the exhaust fan failed to rotate despite the system status showing "ON". **My Post-Mortem Investigation:** 1. **Mechanical Integrity:** The use of jumper wires on the relay output had low resistance to vibration. When the device was moved, the connection became loose. 2. **Contact Resistance:** I identified high contact resistance in the fuse holder, causing momentary power instability. 3. **The Solution:** For industrial-grade reliability, I concluded that moving from prototypes to **permanent terminal blocks and custom PCBs** is a non-negotiable requirement. --- ## Performance Results Despite the mechanical connection challenge, the software logic performed accurately. The system successfully maintained a stable "Dead Zone" with a maximum deviation of only **±0.8°C** during test runs.

Graphical data showing the system reaching stability at 27°C after a pre-heating phase.

--- ## Future Improvements * **Sensor Precision:** Replacing the DHT-11 with a higher accuracy sensor to reduce the current ±2°C tolerance for medical applications. * **Industrial Wiring:** Designing a custom PCB to eliminate jumper wire risks and improve aesthetic organization. * **Connectivity Indicators:** Adding a local LED or OLED indicator specifically for Wi-Fi signal status.

Thermal Chamber - IoT Precision Climate Control

The Story