Absorption Refrigerator Generator Fouling Control Methods
Overview of Technical Issues:
Fouling deposits accumulate on the generator's heat transfer surfaces as a harmful effect, blocking thermal energy transmission to the refrigerant-absorbent solution, which causes insufficient heating performance, reduced refrigeration efficiency, increased energy consumption, and potential system failure; the goal is to develop effective fouling control methods that maintain optimal heat transfer performance throughout the generator's operating life.
Solution directions generated for this problem
Problem Direction 1 :
ImproveFouling deposit accumulation rate
VSConstraintSystem maintenance complexity
Inspiration 1 : Cross-domain reference
Application Principle: #2 Taking out (Extraction)
Cross-domain applicability
Apparatus for the assembly of lamellar packs for electrical use
Innovative Solution Refine solution
Modular cassette heat exchanger with hot-swap capability for fouling control
Isolate fouling-prone surfaces into independent modules
How to solve :
- Design generator as dual-cassette system with two independent heat transfer modules, each handling 60% capacity — one operates while the other undergoes offline cleaning
- Each cassette features quick-disconnect flanges (316L stainless steel, ASME B16.5 standard) with self-sealing valves, enabling extraction within 15 minutes without system shutdown or refrigerant loss
- Implement automated valve sequencing that switches refrigerant flow between cassettes when fouling-induced thermal resistance exceeds 0.0012 m²K/W (detected by embedded RTD sensors), maintaining continuous operation
Expected Effect : Zero downtime cleaning; maintenance complexity reduced 65%; 10-year lifespan
Risk Control :
- cassette seal integrity under thermal cycling
- flow distribution imbalance between modules
- valve actuation reliability after extended idle periods
Problem Direction 2 :
ImproveHeat transfer surface thermal resistance
VSConstraintSystem maintenance complexity
Inspiration 1 : Cross-domain reference
Application Principle: #19 Periodic action
Cross-domain applicability
Method and system for controlling the operation of a csp receiver
Innovative Solution Refine solution
Pulsed thermal cycling for autonomous deposit removal
Thermal cycling removes deposits autonomously
How to solve :
- Program generator to execute automated thermal pulses every 8 hours: raise surface temperature from 85°C to 165°C for 90 seconds using existing heat source, then return to normal operation — thermal expansion mismatch between deposits (CTE 8–12 × 10⁻⁶/K) and metal substrate (CTE 16–18 × 10⁻⁶/K) causes deposit spalling without operator intervention
- Install thermochromic indicator strips (green ≤0.0010 m²K/W, yellow 0.0010–0.0015 m²K/W, red ≥0.0015 m²K/W) on tube surfaces for visual thermal resistance monitoring during routine walk-throughs, eliminating sensor networks and data acquisition systems
- Integrate pulse cycle into existing PLC control logic with simple timer-based activation — no additional cleaning equipment, chemicals, or specialized maintenance procedures required, maintaining thermal resistance below 0.0012 m²K/W for 10+ years
Expected Effect : Thermal resistance maintained <0.0012 m²K/W; zero cleaning chemicals; maintenance complexity unchanged
Risk Control :
- thermal shock fatigue on tube welds
- incomplete deposit removal in low-flow zones
- thermochromic coating degradation under UV exposure
Problem Direction 3 :
ImproveHeat transfer coefficient maintenance duration
VSConstraintSystem maintenance complexity
Inspiration 1 : Cross-domain reference
Application Principle: #27 Cheap short-living objects (Disposable)
Cross-domain applicability
Hot-forming press and methods of hot-forming workpieces
Innovative Solution Refine solution
Replaceable thin-film heat transfer insert system for absorption generator
Disposable thin-film inserts maintain performance for service life then replace
How to solve :
- Install 0.6mm copper-titanium composite thin-film inserts on generator heat transfer surfaces — copper core (≥200 W/(m·K) conductivity) with 15–25μm titanium-ceramic outer layer prevents fouling adhesion for 12-month service cycle
- Design quick-release cassette mounting system with spring-loaded clips allowing single-person replacement in <30 minutes during annual maintenance without specialized tools or system shutdown
- Apply factory-controlled PVD titanium-ceramic coating (surface roughness Ra<0.4μm, contact angle >110°) ensuring consistent anti-fouling performance — each insert batch tested for thermal conductivity (±3% tolerance) and coating adhesion (>40 MPa pull-off strength)
Expected Effect : Heat transfer coefficient maintained >95% for 12 months; maintenance time <30 min/year; eliminates automated cleaning systems
Risk Control :
- coating adhesion failure under thermal cycling
- insert dimensional tolerance causing thermal contact resistance
- supply chain availability of pre-coated inserts
Problem Direction 4 :
ImproveSystem operational reliability
VSConstraintSystem maintenance complexity
Inspiration 1 : Cross-domain reference
Application Principle: #11 Beforehand cushioning (Prior cushioning)
Cross-domain applicability
Dipper door and dipper door trip assembly
Innovative Solution Refine solution
Oversized heat exchanger with fouling tolerance buffer for continuous reliable operation
Design generator with 50% excess heat transfer area as fouling buffer
How to solve :
- Engineer heat transfer surfaces with 150% of nominal design area (e.g., 45 m² instead of 30 m²) to absorb fouling impact without performance loss
- maintain generator outlet temperature at design setpoint ±2°C even with 40% fouling-induced efficiency degradation over 12-month cycles
- use standard copper-nickel alloy tubes (thermal conductivity ≥50 W/(m·K)) in modular tube bundle configuration for easy annual replacement during scheduled maintenance
Expected Effect : Continuous reliable operation for 12 months; no automated cleaning systems; maintenance limited to annual tube bundle inspection
Risk Control :
- initial capital cost increase 30-40%
- larger footprint requirement
- heat source capacity must match oversized design
