Heat Requirement Calculator

The Heat Requirement Calculator determines the energy needed for drying processes including sensible heat, latent heat, and total energy requirements. Essential for kiln design, energy planning, and process optimization.

Modify the values and click the calculate button to use
Material Type
Material Weight (Dry Basis) kg
Initial Moisture Content % (wet basis)
Final Moisture Content % (wet basis)
Initial Temperature °C
Drying Temperature °C
Specific Heat of Material kJ/kg·°C
Process Efficiency %
Heat Loss Factor %

Related Drying Time Calculator | Kiln Drying Calculator | Evaporation Rate Calculator

Understanding Heat Requirements for Drying

Drying processes require energy to heat the material and evaporate moisture. Understanding heat requirements is essential for equipment sizing, energy planning, and cost estimation.

Types of Heat in Drying

Sensible Heat

Definition: Heat required to raise temperature of material and water

Formula: Qsensible = m × cp × ΔT

Components:

  • Heat material from initial to drying temperature
  • Heat water from initial to evaporation temperature
  • Heat air for drying process

Latent Heat

Definition: Heat required to evaporate water

Formula: Qlatent = mwater × hfg

Values:

  • At 100°C: 2257 kJ/kg
  • At 60°C: 2358 kJ/kg
  • At 20°C: 2454 kJ/kg

Heat Requirement Components

Primary Heat Requirements

Secondary Heat Requirements

Calculation Methods

Basic Heat Balance

Total Heat = Sensible Heat + Latent Heat + Losses

Qtotal = Qsensible + Qlatent + Qlosses

Practical Formula:

Qtotal = (Qsensible + Qlatent) / η

Where η = process efficiency

Detailed Calculations

  1. Calculate water to be removed: mwater = minitial - mfinal
  2. Calculate sensible heat: Qs = (mmaterial × cp,mat + mwater × cp,water) × ΔT
  3. Calculate latent heat: Ql = mwater × hfg
  4. Add heat losses: Qlosses = (Qs + Ql) × loss factor
  5. Calculate total: Qtotal = Qs + Ql + Qlosses

Material Properties

Material Specific Heat (kJ/kg·°C) Typical Drying Temp (°C) Energy Factor
Wood (Oak) 1.5-2.0 60-80 3000-4000 kJ/kg water
Grain (Corn) 1.8-2.2 40-60 2800-3500 kJ/kg water
Paper 1.3-1.7 150-200 2500-3000 kJ/kg water
Textiles 1.2-1.8 80-120 2700-3200 kJ/kg water

Energy Efficiency Factors

Process Efficiency

Heat Loss Sources

Energy Sources and Costs

Common Energy Sources

Energy Source Energy Content Efficiency Applications
Natural Gas 37 MJ/m³ 80-90% Most kilns
Electricity 3.6 MJ/kWh 95-98% Dehumidification
Wood Waste 15-20 MJ/kg 70-80% Sawmill kilns
Steam 2.3 MJ/kg 85-95% Industrial plants

Optimization Strategies

Heat Recovery

Process Improvements

Economic Analysis

Energy Cost Calculation

Energy Cost = (Total Heat Required / Fuel Heating Value / Efficiency) × Fuel Cost

Example:

  • Total heat required: 10,000 MJ
  • Natural gas: 37 MJ/m³, 80% efficiency
  • Gas cost: $0.30/m³
  • Energy cost = (10,000 / 37 / 0.8) × $0.30 = $101

Cost Factors

Environmental Considerations

Emissions

Sustainability

Note: Heat requirement calculations provide estimates based on theoretical models. Actual energy consumption may vary due to material properties, equipment efficiency, operating conditions, and heat losses. Use safety factors and validate with actual measurements for critical applications.