Discussion Overview
The discussion revolves around the mass flow rates and temperatures of exhaust gases from light gasoline internal combustion engines, particularly in the context of analyzing waste heat recovery. Participants seek actual values and explore various factors influencing these parameters.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
- Mathematical reasoning
Main Points Raised
- Some participants mention that engineering thermodynamics textbooks, such as Çengel's, may provide useful examples and values related to internal combustion engines.
- One participant emphasizes the need for actual values of mass flow rates and exhaust gas temperatures for studying waste heat recovery, noting that modern car engines typically have around 30% thermal efficiency.
- Another participant states that exhaust temperatures can exceed 800°C during peak operation but generally range from 250-500°C during normal operation.
- There is a mention of a rule of thumb regarding heat dissipation, suggesting that about one-third of the heat is lost through the radiator and another third through the exhaust.
- One participant proposes that the mass flow rate of exhaust gases could be calculated using the mass air flow rate plus the weight of the fuel, factoring in volumetric efficiency and air/fuel ratio.
- Another participant highlights the importance of specific heat of exhaust gases, noting that it may vary significantly at high temperatures and pressures compared to standard conditions.
Areas of Agreement / Disagreement
Participants express varying views on how to obtain the necessary values and calculations related to exhaust gases, with no consensus reached on specific figures or methods. Multiple competing approaches and models are presented.
Contextual Notes
Participants note the dependence on various assumptions, such as the specific heat of exhaust gases at different conditions and the efficiency of engines, which may affect the calculations and results discussed.