Evaporator Flow Passage Expansion to Prevent Working Fluid Overheating
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Solution Overview
Problem
Existing Rankine cycle systems face the challenge of locally increased heat source gas flow rates, which can lead to excessive heating and degradation of the working fluid, hindering system performance.
Innovation Solution
The introduction of an evaporator design featuring an increasing portion in the heat source gas passage and a flow regulating plate with a specific open area ratio, which gradually increases the cross-sectional area and regulates the flow rate to prevent excessive heating, allowing the working fluid to reach a higher temperature without degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heat source gas passage has a uniform cross-sectional area, then the structure is simple, but the heat source gas flow rate increases locally causing excessive heating and working fluid degradation
Solution Approach 1:
The heat source gas passage is divided into multiple sections with different cross-sectional areas. The passage includes a first section with a smaller cross-sectional area and a second section with a larger cross-sectional area, creating distinct flow zones that prevent local flow concentration and excessive heating of the working fluid.
Solution Approach 2:
Different sections of the heat source gas passage are designed with different cross-sectional areas to create localized flow characteristics. The first section has a smaller area to maintain higher velocity and heating efficiency, while the second section has a larger area to reduce flow rate and prevent excessive heating, allowing each zone to perform its specific function optimally.
2Temperature
If the heat source gas flow rate is increased to improve heating efficiency, then the working fluid can be heated to higher temperatures, but the working fluid may be excessively heated and degraded
Solution Approach 1:
The heat source gas passage is segmented into a first section with smaller cross-sectional area for intensive heating and a second section with larger cross-sectional area for flow rate reduction. This segmentation allows the working fluid to reach higher temperatures in the first section without being excessively heated, as the flow rate is reduced in the second section to prevent degradation.
Solution Approach 2:
The cross-sectional area parameter of the heat source gas passage is changed along the flow direction, transitioning from a smaller area in the first section to a larger area in the second section. This parameter change enables control over the heat source gas flow rate and velocity, allowing optimal heating conditions to be maintained while preventing working fluid degradation.
3Loss of energy
If the cross-sectional area of the heat source gas passage is increased, then the pressure loss is reduced, but the heating portion becomes less effective
Solution Approach 1:
The heat source gas passage is divided into a first section with smaller cross-sectional area for effective heating and a second section with larger cross-sectional area for pressure loss reduction. This segmentation allows the system to achieve both effective heating in the first section and reduced pressure loss in the second section, optimizing overall system performance.
Solution Approach 2:
Different sections of the heat source gas passage are designed with different cross-sectional areas to optimize local functions. The first section has a smaller area to maintain high velocity and effective heating, while the second section has a larger area to reduce flow resistance and pressure loss, allowing each zone to perform its specific function optimally.
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 design enables the working fluid to be heated to a higher temperature while preventing excessive heating, thereby enhancing the performance of the Rankine cycle system and reducing the risk of pyrolysis, while maintaining sufficient pressure loss suppression.
Implementation Method 1
an increasing portion that is located between the introducing portion and the heating portion, that constitutes the heat source gas passage, and at which a cross-sectional area of the heat source gas passage gradually increases from an upstream side towards a downstream side in the heat source gas passage
Implementation Method 2
a heating portion that is disposed in the heat source gas passage and at which a working fluid is heated by the heat source gas
Data Source
AI summary
An evaporator includes an introducing portion that introduces a heat source gas from a heat source gas pipe, a heat source gas passage through which the heat source gas introduced from the introducing portion flows, a heating portion that is disposed in the heat source gas passage and at which a working fluid is heated by the heat source gas, an increasing portion at which a cross-sectional area of the heat source gas passage gradually increases from an upstream side towards a downstream side in the heat source gas passage, and a flow regulating plate that is disposed on an upstream side from the heating portion in the heat source gas passage and that has a plurality of holes which allow the heat source gas to pass through the plurality of holes.