Immersion-cooled digital projector

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Overview

This document proposes a novel approach to digital projector design utilizing a dual-cooling system: primary dielectric fluid immersion with a secondary water cooling jacket. The design eliminates traditional fan cooling in favor of passive thermal management, offering increased reliability, silent operation, and improved thermal efficiency.

Core Design Principles

  1. Passive cooling through natural convection
  2. Solid-block optical design
  3. Distributed heat source layout
  4. Dual-fluid cooling system
  5. Simplicity and reliability

Key Components

Optical Block

The core component is a precision-machined solid aluminum block that integrates:

  • Optical path with glass inserts
  • Component mounting points
  • External cooling fins
  • Thermal management pathways

This solid-block approach eliminates air spaces and maximizes thermal conductivity, with mounting points distributed to optimize heat distribution.

Thermal Management System

The design employs two cooling layers:

  1. Primary Cooling: Dielectric Fluid
  2. Completely immerses all electronics
  3. Natural convection circulation
  4. Direct contact with components
  5. Multiple convection paths
  6. Efficient heat distribution throughout fluid volume
  7. Secondary Cooling: Water Jacket
  8. Simple water-filled outer case
  9. Small top opening for evaporation
  10. Easy refill access
  11. Natural evaporative cooling

Case Design

Dimensions: 20cm × 20cm × 10cm Construction:

  • Inner case: Aluminum with dielectric fluid
  • Outer case: Water jacket
  • Small top opening for evaporation/refilling
  • Simple design without complex sealing mechanisms

Component Layout

Distributed Heat Source Design

Components are strategically placed throughout the case to optimize fluid dynamics:

  1. Light Source:
  2. Primary heat generator (≈70% of heat load)
  3. Integrated into aluminum block
  4. Creates local convection current
  5. Direct thermal coupling to fluid
  6. DMD/LCD Panel:
  7. Secondary heat source (≈20% of heat load)
  8. Positioned for optimal fluid flow
  9. Temperature-stabilized mounting
  10. Separate convection path from light source
  11. Power and Control Electronics:
  12. Lower heat generation (≈10% of heat load)
  13. Distributed across available space
  14. Benefits from natural fluid mixing
  15. Creates additional minor convection currents

Heat Distribution Benefits

  • Multiple small convection currents create better fluid mixing
  • No concentrated hot spots
  • Utilizes entire fluid volume effectively
  • More uniform temperature distribution
  • Better overall system cooling

Optical System Integration

The solid aluminum block serves dual purposes:

  1. Optical Bench:
  2. Precision-machined light path
  3. Stable mounting points
  4. Glass-sealed optical tunnel
  5. Protected optical components
  6. Heat Spreader:
  7. Distributes heat into fluid
  8. Multiple thermal paths
  9. Integrated cooling fins
  10. Efficient heat transfer

Fluid Dynamics

Dielectric Fluid Properties

  • High thermal conductivity
  • Excellent heat capacity
  • Natural mixing properties
  • Efficient heat distribution

Natural Convection

  • Multiple small convection currents
  • Enhanced fluid mixing
  • Uniform temperature distribution
  • Self-regulating flow patterns

Water Management

Simple and effective design:

  • Basic outer case water jacket
  • Small top opening serving dual purposes:
    • Water evaporation
    • Easy refilling
  • Visual water level monitoring
  • Minimal maintenance required

Technical Specifications

Fluid Volumes

  • Inner case (dielectric): 2.8 liters
  • Electronics volume: 1.2 liters
  • Water jacket volume: ~2 liters

Thermal Capacity

  • Heat absorption: ~79,800 Joules
  • Continuous power handling: 150W
  • Surface area for heat transfer: 0.16 m²

Advantages

  1. Thermal Efficiency
  2. Distributed heat load
  3. Efficient fluid mixing
  4. Natural convection flow
  5. Dual-fluid cooling system
  6. Reliability
  7. No fans or moving parts
  8. Simple water management
  9. Minimal failure points
  10. Even temperature distribution
  11. Maintenance
  12. Easy water level monitoring
  13. Simple refill process
  14. Minimal required maintenance
  15. No complex mechanisms
  16. Performance
  17. Silent operation
  18. Consistent cooling
  19. Stable temperatures
  20. Optimal component protection

Next Steps

  1. Prototype construction
  2. Thermal performance testing
  3. Evaporation rate measurement
  4. Long-term reliability testing
  5. Cost optimization

Conclusion

This refined design emphasizes simplicity and reliability while maintaining excellent cooling performance. The distributed heat source layout maximizes the natural properties of the dielectric fluid, while the dual-fluid system provides efficient heat dissipation without complex mechanisms. The design achieves its cooling goals through natural fluid dynamics rather than mechanical complexity.

Would you like me to expand on any particular aspect of this final design?

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