Cause: The free version may have limited save functions. Solution: Upgrade to a paid license, or use the built-in "Print to PDF" workaround.
In most cases, PhET Faraday Lab or LTspice will do the job better and safer, without the need for a risky download. Unilab Coils Software Free Download
This logic can be copied into Excel to create your own "Mini-Unilab." Cause : The free version may have limited save functions
1. Input Variables:
2. The Core Logic (Simplified Estimation Formula): While Unilab uses complex logarithmic mean temperature difference (LMTD) loops, you can estimate the Heat Capacity ($Q$) using the sensible heat formula and an assumed effectiveness ($\epsilon$): This logic can be copied into Excel to
$$Q \approx \epsilon \times C_min \times (T_ae - T_we)$$
3. Python Code Prototype (The "Free" Helper): You can run this code right now in any free Python environment (like Google Colab or Replit) to get a rough estimate.
def estimate_coil_performance():
print("--- Unilab-Style Coil Estimator ---")
# 1. Inputs
try:
air_flow_m3h = float(input("Enter Airflow (m3/h): "))
t_air_in = float(input("Enter Air Inlet Temp (°C): "))
t_water_in = float(input("Enter Water Inlet Temp (°C): "))
water_flow_lpm = float(input("Enter Water Flow (l/min): "))
# 2. Constants (Simplified)
# Specific heat of air ~ 1.006 kJ/kgK, Density ~ 1.2 kg/m3
# Specific heat of water ~ 4.18 kJ/kgK
m_air = air_flow_m3h * 1.2 / 3600 # kg/s
m_water = water_flow_lpm / 60 # kg/s (approx density 1)
c_air = m_air * 1006 # W/K
c_water = m_water * 4180 # W/K
# 3. NTU Method Approximation
# Assuming a standard counter-flow coil effectiveness of 0.7
effectiveness = 0.7
c_min = min(c_air, c_water)
q_kw = effectiveness * c_min * (t_air_in - t_water_in) / 1000
# 4. Calculate Outlet Temperatures
if c_air < c_water:
t_air_out = t_air_in - (q_kw * 1000) / c_air
t_water_out = t_water_in + (q_kw * 1000) / c_water
else:
# Logic for water limited scenario
t_air_out = t_air_in - (q_kw * 1000) / c_air
t_water_out = t_water_in + (q_kw * 1000) / c_water
print(f"\nEstimated Results:")
print(f"Capacity: q_kw:.2f kW")
print(f"Leaving Air Temp: t_air_out:.2f °C")
print(f"Leaving Water Temp: t_water_out:.2f °C")
except ValueError:
print("Please enter valid numbers.")