17-22 Nov

This week was largely dedicated to defining the core intention behind our BSF environmental black box project. We began by understanding the purpose and objective of building a chamber that can reliably maintain the ideal conditions needed for Black Soldier Fly larvae. The discussions helped us shape a clear picture of how temperature, humidity, and airflow interact in a controlled 1 m³ environment, and how these factors directly affect BSF growth efficiency.

A major part of the week revolved around exploring multiple ways to achieve the environmental stability we needed. We evaluated different heating and humidification concepts, debated their pros and cons, and mapped out several possible engineering routes. The goal was not to finalize the hardware yet, but to understand the system deeply enough to choose the most efficient and reliable approach later.

Key Discussions This Week

We spent most of the week discussing the objective, purpose, and engineering requirements that would define the system:

  • Why the chamber is needed
  • What environmental parameters must be controlled
  • Hardware approaches to achieve stable heat + humidity
  • How BSF biology interacts with environmental control

We explored multiple pathways for building this system:

  1. Steam-based heating + humidification
  2. Resistive heating + ultrasonic humidification
  3. Fan Pad system

Alongside these discussions, I also worked on an AC-to-DC converter using a bridge rectifier. This small side task is an important building block for the larger system, as it will support the power needs of sensors, controllers, and possibly auxiliary components within the chamber.

24-29 Nov

Calculations, Thermodynamics, and Component Selection

Week 2 marked a shift from conceptual thinking to concrete engineering calculations. The entire thermodynamic profile of the chamber was analyzed—how much heat is required, how the chamber air behaves, how water contributes to humidity and thermal load, and how airflow affects the environment. This analytical phase was essential to determine the exact specifications of the components we will need.

All critical thermodynamic calculations were performed to determine:

  • Energy needed to heat the entire chamber
  • Heat absorbed by air
  • Heat absorbed by water
  • Energy required for evaporation
  • Required airflow (CFM)
  • Fan sizing
  • Heater capacity
  • Worst-case operating conditions

To design the system realistically, we assumed the worst-case starting condition: the chamber beginning at 10°C and needing to reach a stable 27–30°C with around 70% relative humidity. Using thermodynamic formulas, especially Q = m × Cp × ΔT, we calculated the energy required to raise the temperature of the 1 m³ air volume. Additional calculations were done for water heating and evaporation, since humidity control is just as important as heat for BSF larvae.

Key Thermodynamic Outcomes

  • Heat required to warm chamber air: ~21.4 kJ
  • Heat required to heat and evaporate water: ~17.44 kJ
  • Total thermal energy needed: 38.84 kJ

These numbers include both sensible heating and latent heat required for water evaporation, ensuring that both temperature and humidity targets could be reached simultaneously. All calculations were validated using standard thermodynamic values such as air density, specific heat capacities, and latent heat of vaporization.

Component selection is done based on calculations and considering various factors

1.Water Heater (Boiling-based humidification + heating)

    We selected a small water heater capable of boiling water to generate hot steam.
    This solves two problems at once:

    • Raises humidity naturally
    • Adds heat to the chamber efficiently

    This approach is simpler and more controllable compared to ultrasonic humidifiers in humid environments.

    2. Resistive Air Heater

    A resistive-type heating element will maintain a stable temperature between 27–30°C, compensating for:

    • Heat loss to the environment
    • Variations in larval activity
    • External temperature fluctuations

    3. Air Circulation Fan (100 CFM)

    Using your calculations based on:

    • Required air changes per hour
    • Chamber volume
    • Flow stability

    the ideal fan size came out to around 35–60 CFM for stable exchange, but we opted for a 100 CFM fan to ensure:

    • Strong initial equalization
    • Better mixing
    • Future scalability

    The fan will run at controlled duty cycles to maintain ideal airflow without drying the larvae.