Bottoming Cycle Enthalpy Control via Bypass Mixer
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Solution Overview
Problem
In bottoming cycle heat recovery apparatuses, controlling the temperature of the working fluid entering the condenser is challenging due to varying heat loads, which affects the efficiency of the condensation process.
Innovation Solution
The apparatus includes a mixer connected downstream of the expander and upstream of the condenser, with valves and bypass lines to control the flow of working fluid, and optional cooling jackets, utilizing devices like Venturi or ejector mixers to mix condensed and bypass fluids, reducing the heat load on the condenser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If working fluid is directed directly to the condenser from the expander, then the condenser handles the full heat load, but the temperature control and condensation efficiency become difficult
Solution Approach 1:
The working fluid flow is segmented into multiple paths: a main flow through the expander and a bypass flow that can be independently controlled. The bypass valve allows a portion of the working fluid to bypass the expander and mix with the expanded fluid before entering the condenser, enabling independent control of the heat load and temperature entering the condenser.
Solution Approach 2:
The mixer acts as an intermediary device between the expander outlet and the condenser inlet. It combines the expanded working fluid with bypass fluid, serving as a mediation mechanism to adjust and control the temperature and heat load of the working fluid before it enters the condenser, thereby improving temperature control ease.
2Loss of energy
If the heat load on the condenser is high, then more heat can be recovered, but the condensation process efficiency decreases
Solution Approach 1:
The system dynamically adjusts the bypass valve opening to control the amount of bypass fluid mixing with the expanded working fluid. This dynamic control allows the system to optimize the heat load on the condenser in real-time, balancing heat recovery maximization with condensation efficiency maintenance.
Solution Approach 2:
The system changes the temperature and pressure parameters of the working fluid entering the condenser by adjusting the bypass flow ratio. By controlling the mixing of bypass fluid with expanded fluid, the system optimizes the enthalpy and temperature parameters to maintain optimal condensation conditions while maximizing heat recovery.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively manages the heat load by mixing fluids to reduce the temperature and energy input to the condenser, enhancing the efficiency of the waste heat recovery process and improving the operational conditions for the working fluid.
Implementation Method 1
a mixer connected on the working fluid circuit downstream of the expander and upstream of the condenser... to mix condensed and bypass fluids, reducing the heat load on the condenser
Implementation Method 2
working fluid exiting the expander is directed to a condenser which removes sufficient heat from the working fluid to return it to liquid state
Implementation Method 3
a pump connected on the working fluid circuit to receive working fluid exiting the condenser and direct the working fluid under pressure to the boiler
Data Source
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AI summary
A waste heat recovery apparatus, for use with an internal combustion engine, includes a working fluid circuit to circulate working fluid, a boiler connected on the working fluid circuit and adapted to recover waste heat from a source to heat working fluid, an expander connected on the working fluid circuit to receive working fluid from the boiler, and a condenser to receive and condense working fluid from the expander. A line carries condensed working fluid from the outlet side of the condenser to a mixer on the outlet side of the expander to lower the enthalpy of the working fluid entering the condenser.