WASTE HEAT RECOVERY Flashcards
Waste Heat Recovery Definition
Repurposing heat energy which would typically be discarded or emitted to atmosphere.
Percentage of energy lost to heat of each system. 1.Steam system, 2.power generation, 3.energy distribution, 4.energy conversion, 5.motor systems.
- 30-35%
- 24-45%
- 3%
- 10-50%
- 30-80%
What is the ONE advantage of waste heat recovery.
Reduced CO2 emissons.
Describe the quality of waste heat from these sources; 1.Heat in flue gases, 2.Heat in vapour streams, 3.Heat loss from equipment, 4. Heat stored in produce, 5. Heat in exit gas
1.High Temperature, high potential for recovery
2.High Temperature, high potential for recovery
3. Low grade
4. Quality depends on operating temperature
5. Poor if heavily contaminated
Where could high temperature heat recovery be applied?
Industrial applications
Heat process’ with high temperature outputs 600C<
Where could medium temperature heat recovery be applied?
Drying, preheating, space heating
Heat process’ with mid temp outputs 150-600C
Where could low temperature heat recovery be applied?
Heating water for buildings, district heating
Heat process’ with low temp outputs 150C>
Name the 5 types of waste heat recovery.
Economiser
Recuperators
Convective Recuperators
Heat Pipe
Plate Heat Exchanger
Describe the economiser waste heat recovery process.
Heat exchange between flue gases through walls (combustion air for preheating on one side and waste heat stream on other)
Describe the recuperator waste heat recovery process.
Heat exchange between flue gases through walls (combustion air for preheating on one side and waste heat stream on other)
Describe the convective recuperator waste heat recovery process.
Hot gas through small diameter tubes, tubes are baffled to allow gas to pass over them. baffling increases heat exchange.
Describe the heat pipe waste heat recovery process.
Used for HVAC applications
Describe the plate heat exchanger waste heat recovery process.
Parallel plates form a thin flow pass, avoids high cost of heat exchange surfaces. when cold and hot flows are opposite, arrangement is counter current.
