Wine Production
Wine production requires precise refrigeration control across multiple process stages, from fermentation temperature management to cold stabilization and long-term barrel storage. Each wine variety demands specific thermal conditions to develop desired flavor profiles, prevent spoilage, and achieve chemical stability.
Fermentation Temperature Control
Fermentation generates metabolic heat that must be removed to maintain target temperatures. Heat generation rate depends on sugar concentration, yeast activity, and fermentation stage.
Heat Release During Fermentation:
Q_fermentation = 25 BTU/lb sugar metabolized (approximately)
For a 1000-gallon fermentation tank with 22°Brix must:
- Sugar content: 1000 gal × 8.34 lb/gal × 1.09 SG × 0.22 = 2,010 lb sugar
- Total heat release: 2,010 lb × 25 BTU/lb = 50,250 BTU
- Peak heat generation rate: 10,000-15,000 BTU/hr during active fermentation
White Wine Fermentation
White wines require lower fermentation temperatures to preserve delicate aromatic compounds and prevent volatile ester loss.
| Parameter | Cool Fermentation | Standard Fermentation |
|---|---|---|
| Temperature Range | 50-60°F (10-16°C) | 60-68°F (16-20°C) |
| Duration | 14-30 days | 7-14 days |
| Cooling Load (per 1000 gal) | 8,000-12,000 BTU/hr | 6,000-10,000 BTU/hr |
| Volatile Ester Retention | High | Moderate |
| Fruit Character | Enhanced | Standard |
Cooling Methods:
- Jacketed fermentation tanks with glycol circulation
- Internal cooling coils (stainless steel)
- External heat exchangers with must recirculation
- Controlled-temperature room with tank insulation
Glycol systems typically operate at 28-32°F (-2 to 0°C) with 30-35% propylene glycol concentration to provide adequate temperature differential.
Red Wine Fermentation
Red wines ferment at higher temperatures to extract color, tannins, and phenolic compounds from grape skins.
| Parameter | Standard Red | Cold Soak | Extended Maceration |
|---|---|---|---|
| Initial Soak Temperature | N/A | 45-55°F (7-13°C) | N/A |
| Fermentation Temperature | 75-85°F (24-29°C) | 70-80°F (21-27°C) | 75-90°F (24-32°C) |
| Peak Temperature Control | ±2°F | ±2°F | ±3°F |
| Color Extraction | Standard | Enhanced | Maximum |
| Tannin Extraction | Moderate | Controlled | High |
Red wine fermentation requires both cooling and heating capability:
- Cooling during peak fermentation activity
- Heating during cold soak phase and cool ambient conditions
- Temperature ramp control for extended maceration
Barrel Storage Climate Control
Barrel aging requires stable temperature and humidity conditions to control evaporation rates, prevent microbial growth, and ensure consistent wine development.
Temperature Requirements
| Wine Type | Storage Temperature | Tolerance | Annual Temperature Swing |
|---|---|---|---|
| Red Wine Aging | 55-60°F (13-16°C) | ±3°F (±2°C) | <10°F (<6°C) |
| White Wine Aging | 50-55°F (10-13°C) | ±3°F (±2°C) | <8°F (<5°C) |
| Sparkling Wine (tirage) | 50-55°F (10-13°C) | ±2°F (±1°C) | <5°F (<3°C) |
| Premium/Reserve | 55-58°F (13-14°C) | ±1°F (±0.5°C) | <5°F (<3°C) |
Cooling Load Calculation for Barrel Rooms:
Q_total = Q_transmission + Q_barrels + Q_infiltration + Q_lighting + Q_personnel
Where:
- Q_transmission = U × A × ΔT (building envelope heat gain)
- Q_barrels = m_wine × c_p × ΔT + m_evap × h_fg (wine cooling + evaporation)
- Q_infiltration = 1.08 × CFM × ΔT + 0.68 × CFM × Δω (sensible + latent)
Typical barrel room cooling loads: 8-12 BTU/hr per square foot
Humidity Control
Relative humidity affects evaporation rates through barrel staves, impacting both wine volume loss and flavor concentration.
| Relative Humidity | Water Loss | Alcohol Loss | Net Effect |
|---|---|---|---|
| 50-60% | High | Low | Wine concentrates, alcohol increases |
| 65-75% | Moderate | Moderate | Balanced evaporation |
| 75-85% | Low | High | Wine dilutes, alcohol decreases |
| >85% | Minimal | High | Mold risk, excessive alcohol loss |
Target RH: 70-75% for balanced aging
Evaporation rate (angel’s share): 2-4% volume loss per year at 70-75% RH
Humidity Control Methods:
- Direct steam injection (requires pure steam generation)
- Ultrasonic humidification (prevents mineral deposits on barrels)
- Evaporative media with filtered water
- Dehumidification during high ambient humidity periods
Cold Stabilization
Cold stabilization precipitates tartrate crystals before bottling to prevent post-bottling precipitation. This process requires precise low-temperature control.
Process Parameters
| Wine Type | Stabilization Temperature | Hold Time | Tartrate Reduction |
|---|---|---|---|
| White Wine | 25-30°F (-4 to -1°C) | 5-10 days | 90-95% |
| Rosé | 28-32°F (-2 to 0°C) | 5-8 days | 85-90% |
| Red Wine | 30-35°F (-1 to 2°C) | 7-14 days | 80-90% |
| Sparkling Wine (base) | 25-28°F (-4 to -2°C) | 8-12 days | 95-98% |
Cooling Load for Cold Stabilization:
Q_stabilization = (m_wine × c_p × ΔT) / t_cooldown + Q_losses
Example for 5,000 gallons white wine (70°F to 28°F in 24 hours):
- Wine mass: 5,000 gal × 8.5 lb/gal = 42,500 lb
- Specific heat: 0.95 BTU/lb-°F
- Temperature change: 70°F - 28°F = 42°F
- Heat removal: 42,500 × 0.95 × 42 = 1,695,750 BTU
- Required capacity (24 hr): 1,695,750 / 24 = 70,656 BTU/hr
- With safety factor (1.25): 88,320 BTU/hr (7.4 tons)
Contact Stabilization
Accelerated process using potassium bitartrate seeding crystals at cold temperatures.
Process Advantages:
- Reduced hold time: 1-3 days vs. 5-10 days
- Lower energy consumption
- Improved production throughput
- More predictable results
Temperature Control Requirements:
- Rapid cooling to 28-30°F (-2 to -1°C)
- Agitation during crystal addition
- Controlled warming after filtration to prevent thermal shock
Refrigeration System Design
Glycol Circulation Systems
Primary method for fermentation tank and cold stabilization cooling.
System Components:
- Glycol chiller (typically screw or scroll compressor)
- Insulated glycol storage tank (buffer capacity)
- Variable-speed circulation pumps
- Zone control manifolds for individual tank control
- Temperature sensors with ±0.5°F accuracy
Glycol Specifications:
| Application | Glycol Type | Concentration | Supply Temperature | Return ΔT |
|---|---|---|---|---|
| Fermentation Control | Propylene Glycol | 30-35% | 28-32°F (-2 to 0°C) | 8-12°F |
| Cold Stabilization | Propylene Glycol | 35-40% | 20-25°F (-7 to -4°C) | 10-15°F |
| Rapid Cooling | Propylene Glycol | 40-45% | 15-20°F (-9 to -7°C) | 12-18°F |
Flow rate calculation: GPM = (Q_BTU/hr) / (500 × ΔT × SG)
Direct Expansion Systems
Used for barrel room and warehouse cooling where precise individual tank control is not required.
System Characteristics:
- Lower first cost than glycol systems
- Higher energy efficiency for steady-state loads
- Multiple evaporator zones for different storage areas
- Defrost cycles required for low-temperature applications
Typical Configuration:
- Air-cooled condensing units (outdoor installation)
- Multiple ceiling-mounted or wall-mounted evaporators
- Electronic expansion valves for precise superheat control
- Microprocessor controls with humidity management
Heat Recovery Opportunities
Winery refrigeration systems reject substantial heat that can be recovered for process heating.
Heat Recovery Applications:
| Heat Source | Temperature Available | Potential Use | Energy Offset |
|---|---|---|---|
| Chiller Condenser | 95-110°F (35-43°C) | Barrel wash water heating | 30-40% of heat rejected |
| Hot Gas Reheat | 140-160°F (60-71°C) | CIP solution heating | 15-25% of heat rejected |
| Desuperheater | 160-200°F (71-93°C) | Domestic hot water | 10-20% of heat rejected |
Heat recovery effectiveness: 40-60% of total refrigeration energy input
Process Integration Considerations
Harvest Season Peak Loads:
- Fermentation cooling capacity must handle simultaneous tank operation
- Diversity factor: 0.6-0.8 (not all tanks at peak simultaneously)
- Backup capacity recommendation: 20-30% above calculated peak
Energy Efficiency Measures:
- Variable-speed compressors for part-load operation
- Free cooling with glycol-to-air heat exchangers during cold weather
- Thermal storage (ice bank) for peak shaving
- Heat recovery integration with process loads
Control Strategy:
- Individual tank temperature control with ±0.5°F accuracy
- Automated cooling/heating switchover for red fermentation
- Alarm systems for out-of-range conditions
- Remote monitoring and trending
Safety and Sanitary Design:
- Food-grade glycol (propylene glycol, never ethylene glycol)
- Stainless steel wetted surfaces in cooling coils
- CIP-compatible connections and fittings
- Leak detection for glycol systems
- Emergency backup cooling capability for critical fermentations
Sections
Fermentation Temperature Control
HVAC engineering guide to wine fermentation temperature control systems including glycol cooling, jacketed tank design, heat generation calculations, and refrigeration requirements for red and white wine production.
Wine Aging Cellars
HVAC design for wine aging cellars including temperature stability, humidity control, vibration considerations, and environmental parameters for barrel rooms and bottle storage areas
Cold Stabilization Wine
HVAC engineering guide to wine cold stabilization systems including tartrate precipitation temperatures, contact cooling vs jacketed tank refrigeration, stabilization duration by wine type, and energy efficiency optimization for winery refrigeration design.