Collector Efficiency Factor Concentrating Collector Calculator

Formula Used:

\[ F' = \frac{1}{U_l \times \left( \frac{1}{U_l} + \frac{D_o}{D_i \times h_f} \right)} \]

Overall Loss Coefficient (U_l):

W/m²·K

Outer Diameter of Absorber Tube (D_o):

Inner Diameter Absorber Tube (D_i):

Heat Transfer Coefficient Inside (h_f):

W/m²·K

Collector Efficiency Factor (F'):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Collector Efficiency Factor?

The Collector Efficiency Factor (F') is defined as the ratio of the actual thermal collector power to the power of an ideal collector whose absorber temperature is equal to the fluid temperature. It represents how efficiently a solar collector transfers heat from the absorber surface to the working fluid.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ F' = \frac{1}{U_l \times \left( \frac{1}{U_l} + \frac{D_o}{D_i \times h_f} \right)} \]

Where:

\( F' \) — Collector efficiency factor
\( U_l \) — Overall loss coefficient (W/m²·K)
\( D_o \) — Outer diameter of absorber tube (m)
\( D_i \) — Inner diameter absorber tube (m)
\( h_f \) — Heat transfer coefficient inside (W/m²·K)

Explanation: The formula accounts for the thermal resistance network in a concentrating collector, considering both internal and external heat transfer characteristics.

3. Importance of Collector Efficiency Factor

Details: The collector efficiency factor is crucial for evaluating the thermal performance of concentrating solar collectors. It helps in designing efficient solar thermal systems and optimizing heat transfer between the absorber and the working fluid.

4. Using the Calculator

Tips: Enter all values in appropriate units (U_l and h_f in W/m²·K, diameters in meters). All values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range of collector efficiency factor values?
A: Collector efficiency factor typically ranges between 0.8 and 0.95 for well-designed concentrating collectors, with higher values indicating better thermal performance.

Q2: How does tube diameter affect the efficiency factor?
A: Larger inner diameters generally improve heat transfer and increase the efficiency factor, while larger outer diameters may increase thermal resistance and decrease efficiency.

Q3: What factors influence the heat transfer coefficient?
A: The heat transfer coefficient depends on fluid properties, flow regime (laminar or turbulent), flow velocity, and tube surface characteristics.

Q4: Why is the overall loss coefficient important?
A: The overall loss coefficient represents heat losses from the collector to the environment. Lower loss coefficients result in higher collector efficiency factors.

Q5: Can this calculator be used for flat plate collectors?
A: While the basic principle is similar, flat plate collectors have different geometry and heat transfer characteristics, so a different formula would be more appropriate.