Drain Water Heat Recovery Efficiency Calculator

Drain Water Heat Recovery is an efficient way to conserve energy by reusing heat from wastewater or drain water. This process involves capturing the thermal energy from the water, which is then used to pre-heat fresh incoming water or for other applications. To assess the effectiveness of this recovery process, we use the formula that incorporates flow rate, specific heat, temperature difference, and efficiency.

Historical Background

Drain water heat recovery has become a common practice in energy conservation and sustainability efforts, particularly in the building and industrial sectors. The idea is to reduce energy waste by capturing heat that would otherwise be lost through wastewater systems. This technology has grown in importance due to the increasing demand for energy efficiency and reducing carbon footprints in modern infrastructure.

Calculation Formula

The recovered heat is calculated using the formula:

\[ \text{Recovered Heat} = \text{Flow Rate} \times \text{Specific Heat} \times \text{Temperature Difference} \times \text{Efficiency} \]

Where:

• Flow Rate is the amount of water passing through the system, typically measured in kg/s or other units.
• Specific Heat is the heat capacity of the water, typically expressed in kJ/kg°C or similar units.
• Temperature Difference is the change in temperature between the wastewater and incoming water, usually measured in °C or °F.
• Efficiency is the effectiveness of the heat recovery system, expressed as a percentage or fraction.

Example Calculation

Assume:

• Flow Rate = 0.5 kg/s
• Specific Heat = 4.18 kJ/kg°C
• Temperature Difference = 25°C
• Efficiency = 85%

The recovered heat would be:

\[ \text{Recovered Heat} = 0.5 \, \text{kg/s} \times 4.18 \, \text{kJ/kg°C} \times 25°C \times 0.85 = 44.125 \, \text{kJ/s} \, \text{or kW} \]

Importance and Usage Scenarios

Drain Water Heat Recovery is an effective strategy for reducing energy costs in residential, commercial, and industrial buildings. It is especially beneficial in systems where large volumes of hot water are used, such as in hotels, laundry facilities, and manufacturing plants. This process helps conserve energy, lower utility bills, and reduce environmental impact by reusing energy that would otherwise be wasted.

Common FAQs

1. What is Drain Water Heat Recovery?

   • It is a method of capturing and reusing thermal energy from wastewater to improve energy efficiency, typically used for heating fresh water.

2. How does the efficiency factor affect the calculation?

   • Efficiency refers to how well the system recovers heat. A higher efficiency means more energy is captured, leading to a greater amount of recovered heat.

3. What units can be used in the calculator?

   • The calculator supports various units such as kJ, MJ, and BTU for recovered heat; kg/s, lb/s, and g/min for flow rate; kJ/kg°C, BTU/lb°F, and cal/g°C for specific heat; °C, °F, and K for temperature difference; and percentage or fraction for efficiency.

4. Why is specific heat important in heat recovery?

   • Specific heat is a measure of the water's ability to store thermal energy. A higher specific heat allows the water to store more energy, enhancing the effectiveness of heat recovery.

This calculator allows users to determine the recovered heat in a drain water heat recovery system, offering an easy way to optimize energy conservation efforts.