Caramel Production HVAC Systems

Overview

Caramel production facilities require specialized HVAC systems to manage extreme temperature differentials between cooking and cooling zones, control moisture to prevent crystallization, and maintain precise environmental conditions for wrapping and storage operations. The cooking process generates substantial sensible and latent heat loads from sugar syrup evaporation at temperatures from 115°C to 121°C (239°F to 250°F), while cooling and wrapping areas demand strict humidity control to maintain product texture and prevent sticking.

Critical HVAC Challenges:

• High-temperature cooking area ventilation and heat removal
• Rapid product cooling without surface moisture condensation
• Humidity control for crystallization prevention during cooling
• Wrapping room conditioning to prevent product adhesion
• Segregated environmental zones with minimal cross-contamination

Cooking Area Ventilation Requirements

The caramel cooking zone produces the highest thermal loads in confectionery manufacturing due to continuous sugar syrup boiling and moisture evaporation. Effective ventilation design must capture both sensible heat and water vapor while maintaining worker comfort and process control.

Heat Load Characteristics

Cooking kettle operations generate combined convective and radiant heat loads that scale with production capacity and batch frequency.

Exhaust Hood Design

Canopy hoods positioned directly above cooking kettles provide primary heat and moisture capture. Hood sizing and exhaust rates must accommodate thermal plume expansion and prevent spillage into occupied zones.

Hood Geometry:

• Overhang beyond kettle perimeter: minimum 12 inches all sides
• Hood height above cooking surface: 3.5 to 5 feet optimal
• Hood depth: 24 to 36 inches for adequate plume containment
• Face velocity at hood entry: 100-150 FPM for effective capture

Exhaust Flow Rates:

• Light-duty cooking (intermittent): 100-150 CFM per square foot hood area
• Medium-duty cooking (continuous batch): 200-300 CFM per square foot
• Heavy-duty cooking (high-temperature processes): 300-400 CFM per square foot

Grease-rated exhaust ductwork constructed from 16-gauge galvanized steel with welded seams handles the moisture-laden air stream. Duct velocities of 1,800-2,200 FPM prevent condensation accumulation while maintaining acceptable pressure drop.

Makeup Air Delivery

Tempered makeup air replaces exhausted volumes and prevents negative building pressure that compromises exhaust performance and creates door infiltration issues.

Makeup Air Strategies:

• Direct-fired gas makeup air units: 80-85% thermal efficiency
• Indirect-fired units for sensitive production areas: prevents combustion product introduction
• Heat recovery from exhaust stream: 40-60% energy recovery potential
• Supply air temperature: 60-70°F winter, 75-80°F summer
• Distribution through perforated ductwork or displacement diffusers

Supply air delivery points located at floor level or low sidewall positions provide displacement ventilation that flows upward toward exhaust hoods, improving capture efficiency and reducing mixing with occupied zone air.

Cooling Tunnel Design for Caramel

Rapid, controlled cooling transforms hot caramel from cooking temperature (115-121°C) to wrapping temperature (21-27°C) while preventing surface moisture condensation, sugar crystallization, and texture defects. Cooling tunnel design balances heat removal rate with product quality requirements.

Tunnel Configuration

Cooling Zone Specifications

Progressive cooling through multiple temperature zones prevents thermal shock and maintains product integrity.

Zone 1 - Initial Cooling (Hot End):

• Product inlet temperature: 115-121°C (239-250°F)
• Air temperature: 18-24°C (64-75°F)
• Air velocity over product: 400-600 FPM
• Relative humidity: 35-45% RH
• Zone length: 25-30% of total tunnel

Zone 2 - Intermediate Cooling:

• Product temperature range: 60-80°C (140-176°F)
• Air temperature: 15-20°C (59-68°F)
• Air velocity: 300-450 FPM
• Relative humidity: 40-50% RH
• Zone length: 35-40% of total tunnel

Zone 3 - Final Cooling:

• Product exit temperature: 21-27°C (70-81°F)
• Air temperature: 13-18°C (55-64°F)
• Air velocity: 200-350 FPM
• Relative humidity: 45-55% RH
• Zone length: 30-35% of total tunnel

Refrigeration System Design

Cooling tunnels employ direct expansion (DX) or glycol-fed cooling coils sized for peak heat removal during maximum production throughput.

Refrigeration Capacity Calculation:

Q_total = Q_product + Q_belt + Q_infiltration + Q_fans

Where:

• Q_product = m × Cp × ΔT (sensible heat removal from caramel mass)
• Q_belt = continuous conveyor heat capacity
• Q_infiltration = opening area × velocity × air enthalpy difference
• Q_fans = motor brake horsepower × 2,545 BTU/hr/hp

Typical Design Parameters:

• Refrigeration load: 80,000-250,000 BTU/hr depending on production rate
• Evaporator temperature: 28-35°F (prevents coil frosting)
• Refrigerant: R-404A, R-407C, or R-448A for low-temperature applications
• Defrost cycle: electric or hot gas, 2-4 times per 24 hours

Air circulation fans maintain uniform temperature distribution across product width. Fan selection balances air velocity requirements against energy consumption and product surface disturbance.

Temperature and Humidity Control

Precise psychrometric control throughout caramel production prevents quality defects including crystallization, sticking, moisture absorption, and texture variations. Each production zone requires specific dewpoint and dry-bulb temperature maintenance.

Process Zone Environmental Requirements

Humidity Control Systems

Dehumidification Approaches:

1. Refrigeration-Based Dehumidification:

   • Cooling coil dewpoint: 42-48°F achieves 50-55% RH at 70°F space temperature
   • Reheat requirement: 2-4°F temperature rise post-coil
   • Energy efficiency: 0.9-1.2 kW per pound water removed
   • Application: primary method for most production zones

2. Desiccant Dehumidification:

   • Achieves lower dewpoints: 35-45°F capable
   • Independent temperature and humidity control
   • Regeneration energy: 2,000-2,800 BTU/lb water removed
   • Application: wrapping rooms requiring dewpoints below 45°F

3. Hybrid Systems:

   • Refrigeration pre-conditioning followed by desiccant polishing
   • Optimizes energy consumption across varying loads
   • Provides backup humidity control during peak conditions

Humidification (Seasonal):

Winter conditions may require humidity addition in wrapping areas to prevent over-drying and brittleness. Steam injection or evaporative systems maintain target RH without introducing liquid water that could contact product surfaces.

Crystallization Prevention

Sugar crystallization in caramel results from supersaturation conditions created by cooling, moisture absorption, or mechanical agitation. HVAC system design minimizes crystallization triggers through precise environmental control.

Moisture Migration Control

Water vapor differential between product surface and surrounding air drives moisture exchange. Maintaining product temperature slightly above ambient dewpoint prevents surface condensation that initiates crystal formation.

Critical Control Parameters:

• Product surface temperature minus dewpoint: maintain ≥2°F differential
• Air velocity over exposed product: minimize to reduce convective moisture transfer
• Tunnel air dewpoint stability: ±1°F maximum variation
• Relative humidity during cooling: 45-55% RH optimal range

Temperature Gradient Management

Rapid cooling creates internal temperature gradients that drive moisture from the hot center toward cooler surfaces. Controlled cooling rates maintain thermal uniformity within the caramel mass.

Cooling Rate Optimization:

• Maximum safe cooling rate: 3-5°F per minute for thin products
• Thick-slab caramel: 1-2°F per minute prevents cracking and surface defects
• Final 20°F of cooling: reduced air velocity maintains surface quality

Air distribution through slot diffusers or perforated supply plenums provides uniform cooling across product width, preventing edge zones from cooling faster than center sections.

Wrapping Room Environment

The wrapping area demands the most stringent environmental control in caramel production. Product at 21-27°C remains tacky and moisture-sensitive, requiring precise temperature and humidity maintenance to prevent sticking to wrappers, equipment surfaces, and adjacent pieces.

Environmental Specifications

Temperature Control:

• Setpoint: 20°C ± 1°C (68°F ± 2°F)
• Vertical temperature gradient: maximum 2°F floor to ceiling
• Horizontal uniformity: ±1°F across work area
• Control response time: 5-minute recovery from 2°F deviation

Humidity Control:

• Setpoint: 50% ± 3% RH
• Dewpoint: 10-11°C (50-52°F)
• Recovery time: 10-minute return to setpoint after door opening
• Measurement accuracy: ±2% RH calibrated sensors

HVAC System Configuration

Dedicated air handling units serving wrapping rooms only prevent cross-contamination from higher-moisture production areas and provide independent control.

Air Handling Unit Components:

• Supply air fan: variable frequency drive for turndown capability
• Cooling coil: chilled water (40-44°F supply) with 6-8 rows depth
• Reheat coil: hot water or electric for precise humidity control
• MERV 11-13 filtration: removes particulates that contaminate product
• Return air economizer: disabled to maintain humidity control

Air Distribution:

• Supply air diffusers: low-velocity displacement type, 0.3-0.5 air changes per minute
• Return grilles: high sidewall or ceiling locations
• Pressurization: +0.03 to +0.05 inches W.C. relative to adjacent zones
• Air balance: 10-15% outdoor air minimum for code compliance

Heat Load Management

Wrapping room cooling loads include machinery heat, lighting, worker metabolism, and product sensible cooling.

Total cooling capacity sized at 1.15-1.25 times calculated peak load provides headroom for production increases and equipment additions.

Equipment Specifications

Cooling System Equipment

Ventilation Equipment

Control Systems

Building automation system (BAS) integration provides coordinated control of temperature, humidity, and ventilation across all production zones.

Control Capabilities:

• DDC control of all HVAC equipment
• Proportional-integral-derivative (PID) loops for temperature and humidity
• Dewpoint calculation and control sequencing
• Production schedule integration for setback modes
• Alarm notification for out-of-range conditions
• Trending and data logging for quality documentation

Energy Efficiency Considerations

Caramel production HVAC systems consume significant energy due to continuous refrigeration, dehumidification, and exhaust/makeup air heating. Strategic efficiency measures reduce operating costs without compromising product quality.

Energy Conservation Measures:

• Variable frequency drives on all fan motors: 30-50% fan energy reduction
• Heat recovery from cooking area exhaust: 40-60% makeup air heating offset
• Economizer cooling during suitable outdoor conditions: free cooling when available
• LED lighting in all production areas: 50-70% lighting energy reduction
• Insulated building envelope: R-19 walls, R-30 roof minimum
• Demand-controlled ventilation based on production schedule

Monitoring and Optimization:

• Submetering of HVAC electrical loads by zone
• Refrigeration system performance trending
• Compressed air leak detection and repair
• Regular filter replacement maintaining low pressure drop
• Coil cleaning maintaining heat transfer efficiency

Conclusion

Successful caramel production HVAC design requires integration of high-temperature cooking area ventilation, precise cooling tunnel refrigeration, and stringent wrapping room environmental control. System performance directly impacts product quality through crystallization prevention, texture maintenance, and processing efficiency. Proper equipment selection, controls integration, and operational protocols ensure consistent production output while minimizing energy consumption and operating costs.