ORC Evaporator Temperature Control via Heat-Supplying Medium Recirculation
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Solution Overview
Problem
Organic Rankine Cycle (ORC) plants face issues with organic working media decomposition due to high evaporation temperatures, leading to corrosive or poisonous byproducts, and the use of thermal oils in intermediate cycles complicates the system, increases costs, and reduces electrical performance.
Innovation Solution
An apparatus that controls the temperature of the heat-supplying medium in a heat exchanger by recirculating cooled medium and/or adding a further medium, such as ambient air, to maintain the working medium below its decomposition temperature, avoiding excess temperatures and using a shell-and-tube or plate heat exchanger with a fan or vacuum device for efficient recirculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If direct evaporation of organic working medium is used, then electrical performance is improved, but working medium decomposition occurs due to excessive temperature
Solution Approach 1:
The patent introduces a recirculating heat-supplying medium as an intermediary between the heat source and the working medium. This intermediary medium absorbs heat from the source and transports it to the evaporator, preventing direct exposure of the working medium to excessive temperatures that would cause decomposition, while still enabling efficient heat transfer for high electrical performance
Solution Approach 2:
The patent implements a recirculation system where the heat-supplying medium is continuously circulated between the heat source, evaporator, and back to the heat source. This feedback loop allows temperature control and ensures the working medium receives heat at controlled rates, preventing thermal decomposition while maintaining evaporation efficiency
2Reliability
If thermal oil intermediate cycle is used, then working medium temperature is controlled below decomposition temperature, but system complexity and costs increase
Solution Approach 1:
The patent makes the heat-supplying medium serve multiple functions: it acts as both the heat transport medium (replacing thermal oil) and the evaporation medium (replacing the organic working medium in the evaporator). This multi-functionality eliminates the need for separate thermal oil circulation systems, reducing system complexity while maintaining temperature control
Solution Approach 2:
The patent extracts and eliminates the thermal oil intermediate cycle from the system, using the heat-supplying medium directly for both heat transport and evaporation purposes. This removal of the intermediate thermal oil system simplifies the overall plant configuration and reduces operational complexity
3Loss of energy
If thermal oil is used for heat transport, then heat transfer is achieved, but electrical performance is reduced due to pump power consumption
Solution Approach 1:
The patent removes the thermal oil circulation pump from the system by using the heat-supplying medium directly for evaporation. This eliminates the energy consumption associated with pumping thermal oil, thereby improving net electrical performance while maintaining effective heat transfer through the recirculation system
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 approach prevents working medium decomposition, reduces system complexity and costs, and enhances electrical performance by ensuring a more homogeneous heat transfer and reducing the risk of thermal oil oxidation and aging.
Implementation Method 1
a heat exchanger for transferring heat of a heat-supplying medium to a working medium which differs from the heat-supplying medium
Implementation Method 2
a second supply device adapted to supply at least partially the heat-supplying medium, after it has passed through the heat exchanger, and/or a further medium, each having a second temperature which is lower than the first temperature
Implementation Method 3
the heat exchanger may be provided in the form of an evaporator in which the working medium is evaporated
Data Source
AI summary
The present invention provides a device which comprises: a heat exchanger (1) for transferring heat of a heat-supplying medium to a working medium which differs from said heat-supplying medium, a first supply device designed to provide a flow of the heat-supplying medium at a first temperature from a heat source to the heat exchanger, and a second supply device which is designed to deliver the heat-supplying medium after it has passed through the heat exchanger, and/or a further medium at a second temperature lower than the first temperature, to the flow of the heat-supplying medium at the first temperature.