Collection Efficiency When Heat Removal Factor Is Present Calculator

Formula Used:

\[ \eta_i = F_R \times \left(\frac{A_p}{A_c}\right) \times \left(\frac{S_{flux}}{I_T} - \frac{U_l \times (T_{fi} - T_a)}{I_T}\right) \]

Collector Heat Removal Factor (F_R):

Area of Absorber Plate (A_p):

m²

Gross Collector Area (A_c):

m²

Flux Absorbed by Plate (S_flux):

W/m²

Flux Incident on Top Cover (I_T):

W/m²

Overall Loss Coefficient (U_l):

W/m²K

Inlet Fluid Temperature (T_fi):

Ambient Air Temperature (T_a):

Instantaneous Collection Efficiency (η_i):

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1. What is Instantaneous Collection Efficiency?

Instantaneous collection efficiency is defined as the ratio of useful heat gain to radiation incident on the collector. It measures how effectively a solar collector converts incoming solar radiation into usable thermal energy at any given moment.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \eta_i = F_R \times \left(\frac{A_p}{A_c}\right) \times \left(\frac{S_{flux}}{I_T} - \frac{U_l \times (T_{fi} - T_a)}{I_T}\right) \]

Where:

\( F_R \) — Collector heat removal factor
\( A_p \) — Area of absorber plate (m²)
\( A_c \) — Gross collector area (m²)
\( S_{flux} \) — Flux absorbed by plate (W/m²)
\( I_T \) — Flux incident on top cover (W/m²)
\( U_l \) — Overall loss coefficient (W/m²K)
\( T_{fi} \) — Inlet fluid temperature (K)
\( T_a \) — Ambient air temperature (K)

Explanation: The formula accounts for the collector's ability to transfer heat to the working fluid while considering heat losses to the environment.

3. Importance of Collection Efficiency Calculation

Details: Calculating instantaneous collection efficiency is crucial for evaluating solar collector performance, optimizing system design, and predicting energy output under specific operating conditions.

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. Ensure temperature values are in Kelvin and all area/flux values are positive. The calculator will compute the instantaneous efficiency based on the input values.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for collector heat removal factor?
A: The heat removal factor typically ranges between 0.6 and 0.9 for well-designed flat plate collectors.

Q2: How does ambient temperature affect collection efficiency?
A: Higher ambient temperatures reduce heat losses, generally improving collection efficiency, while lower ambient temperatures increase losses and reduce efficiency.

Q3: What is the significance of the absorber plate to collector area ratio?
A: This ratio indicates what portion of the total collector area is actively absorbing solar radiation, affecting the overall energy capture capability.

Q4: How does the overall loss coefficient impact efficiency?
A: A lower loss coefficient indicates better insulation and reduced heat losses, leading to higher collection efficiency.

Q5: Can this calculator be used for different types of solar collectors?
A: This specific formula is primarily designed for flat plate collectors. Other collector types may require different efficiency equations.