.drying-calculator-container {
max-width: 600px;
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padding: 20px;
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border-radius: 8px;
font-family: Arial, sans-serif;
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box-sizing: border-box;
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.drying-input-wrapper {
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.drying-unit-label {
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right: 10px;
top: 50%;
transform: translateY(-50%);
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font-size: 0.9em;
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.calculate-btn {
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Understanding the Drying Rate Formula
The drying rate is a critical parameter in industrial process engineering, particularly in sectors such as food processing, pharmaceuticals, ceramics, and lumber production. It determines how quickly moisture is removed from a solid material per unit of surface area over time.
The Calculation Formula
The drying rate is calculated based on the loss of weight (moisture) relative to the surface area exposed to the drying medium and the time elapsed. The fundamental formula used in this calculator is:
R = (Winitial – Wfinal) / (A × t)
Where:
- R = Drying Rate (kg/m²/h)
- Winitial = Initial weight of the wet material (kg)
- Wfinal = Weight of the material after time t (kg)
- A = Surface area available for evaporation (m²)
- t = Time interval of the drying process (hours)
Why Surface Area Matters
The surface area (A) is the denominator in the equation because drying is a surface phenomenon. Two samples with the same weight but different surface areas will dry at different rates. Spreading a material thinly increases the surface area to volume ratio, typically accelerating the drying process significantly.
Example Calculation
Consider a scenario in a food dehydration plant:
- Initial Weight: 50 kg of sliced fruit.
- Final Weight: 42 kg after drying.
- Surface Area: The trays provide 4 m² of surface area.
- Time: The process ran for 2 hours.
Step 1: Calculate Moisture Loss = 50 kg – 42 kg = 8 kg.
Step 2: Calculate Denominator = 4 m² × 2 h = 8 m²·h.
Step 3: Calculate Rate = 8 kg / 8 m²·h = 1.0 kg/m²/h.
Applications
Accurate drying rate calculations help engineers design dryers, optimize energy consumption, and ensure product quality. If the rate is too high, the surface might harden (case hardening), trapping moisture inside. If too low, the process becomes inefficient and may lead to microbial growth.
function calculateDryingRate() {
// Get input values using var
var wInitial = parseFloat(document.getElementById('initialWeight').value);
var wFinal = parseFloat(document.getElementById('finalWeight').value);
var area = parseFloat(document.getElementById('surfaceArea').value);
var time = parseFloat(document.getElementById('dryingTime').value);
var errorDisplay = document.getElementById('errorDisplay');
var resultDisplay = document.getElementById('resultDisplay');
// Reset display
errorDisplay.style.display = 'none';
resultDisplay.style.display = 'none';
// Validation Logic
if (isNaN(wInitial) || isNaN(wFinal) || isNaN(area) || isNaN(time)) {
errorDisplay.innerText = "Please enter valid numbers for all fields.";
errorDisplay.style.display = 'block';
return;
}
if (wInitial < 0 || wFinal < 0 || area <= 0 || time wInitial) {
errorDisplay.innerText = "Final weight cannot be greater than Initial weight (sample gained mass).";
errorDisplay.style.display = 'block';
return;
}
// Calculations
var moistureLoss = wInitial – wFinal;
var dryingRate = moistureLoss / (area * time);
// Optional Metric: Flux (Loss per hour regardless of area, sometimes useful)
var flux = moistureLoss / time;
// Display Results
document.getElementById('moistureLossResult').innerText = moistureLoss.toFixed(3) + " kg";
document.getElementById('fluxResult').innerText = flux.toFixed(3) + " kg/h";
document.getElementById('rateResult').innerText = dryingRate.toFixed(4) + " kg/m²/h";
resultDisplay.style.display = 'block';
}