Organic Rankine Cycle Heat Exchanger Temperature Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing Organic Rankine Cycle (ORC) systems face challenges in managing high temperatures, leading to working fluid degradation and increased costs due to the use of intermediate thermal fluid systems, which reduce efficiency and increase size.
Innovation Solution
An ORC system with a heat exchanger comprising an evaporator, superheater, and preheater, configured to limit the working fluid temperature below a threshold by optimizing heat exchange between waste heat fluid and the working fluid, using external and internal enhancement features to prevent overheating, and eliminating the need for an intermediate fluid loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an intermediate thermal fluid system is used to convey heat from exhaust to ORC boiler, then working fluid degradation is avoided, but system cost increases by up to one-quarter
Solution Approach 1:
The patent extracts and eliminates the intermediate thermal fluid system from the ORC configuration, allowing the working fluid to be directly exposed to exhaust heat. This is achieved by selecting a working fluid (siloxane) that is inherently resistant to thermal degradation at high temperatures, thereby removing the need for the intermediate oil-based thermal fluid system that previously added significant cost and complexity.
Solution Approach 2:
The patent changes the thermal stability parameter of the working fluid by selecting siloxane-based fluids that can withstand temperatures up to 500°C or higher. This parameter change enables direct exposure to exhaust heat without degradation, eliminating the need for the intermediate thermal fluid system and its associated costs.
2Reliability
If an intermediate thermal fluid system and heat exchangers are used, then working fluid protection is achieved, but temperature difference increases resulting in larger size and lower efficiency
Solution Approach 1:
The patent removes the intermediate thermal fluid system and associated heat exchangers, allowing direct heat transfer from exhaust to the ORC working fluid. This elimination of intermediate components reduces the temperature difference required for heat transfer, thereby improving thermal efficiency and reducing system size.
Solution Approach 2:
The patent uses the exhaust gas itself as the primary heat transfer medium, eliminating the need for an intermediate thermal fluid. The working fluid directly absorbs heat from the exhaust through the heat exchanger, creating a more efficient direct heat transfer path without intermediate mediation that would require larger temperature gradients.
3Device complexity
If working fluid is exposed to high temperature exhaust directly, then system simplicity is improved, but working fluid degradation occurs beyond critical temperature
Solution Approach 1:
The patent fundamentally changes the thermal stability parameter of the working fluid by selecting siloxane-based fluids that can withstand temperatures up to 500°C or higher. This parameter change enables direct exposure to exhaust heat without degradation, achieving both system simplicity and working fluid stability simultaneously.
Solution Approach 2:
The patent employs siloxane-based working fluids that combine the desirable properties of organic fluids with exceptional thermal stability. This composite chemical structure (silicon-oxygen backbone with organic side groups) provides both the low-temperature performance needed for ORC operation and the high-temperature resistance required for direct exhaust heat exposure.
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
The system effectively limits working fluid temperature, enhancing stability and efficiency, reducing capital costs, and allowing for compact designs suitable for various applications, including space-constrained environments.
Implementation Method 1
an evaporator configured to receive the waste heat fluid from the heat source and vaporize the working fluid, wherein the evaporator is further configured to allow heat exchange between the waste heat fluid and the vaporized working fluid
Implementation Method 2
a superheater configured to receive the lower temperature waste heat fluid from the evaporator and is further configured to allow heat exchange between the lower temperature waste heat fluid and a relatively higher temperature working fluid contained in the superheater
Implementation Method 3
a preheater configured to receive the elevated temperature waste heat fluid from the superheater and allow heat exchange with a relatively lower temperature working fluid in a liquid state contained in the preheater
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An ORC system (10) configured to limit temperature of a working fluid (14) below a threshold temperature is provided. The ORC system (10) includes a heat source (16) configured to convey a waste heat fluid (18). The ORC system (10) also includes a heat exchanger (20) coupled to the heat source (16). The heat exchanger (20) includes an evaporator (22) configured to receive the waste heat fluid (18) from the heat source (16) and vaporize the working fluid (14), wherein the evaporator (22) is further configured to allow heat exchange between the waste heat fluid (18) and the vaporized working fluid at an elevated temperature and further produce an evaporator outlet flow including a lower temperature waste heat fluid (31). The heat exchanger (20) also includes a superheater (24) configured to receive the lower temperature waste heat fluid (31) from the evaporator (22), wherein the superheater (24) is further configured to allow heat exchange between the lower temperature waste heat fluid (31) and a relatively higher temperature working fluid contained in the superheater (24) and further produce a superheater outlet flow comprising an elevated temperature waste heat fluid. The heat exchanger (20) further includes a preheater (28) configured to receive the elevated temperature waste heat fluid from the superheater (24) and allow heat exchange with a relatively lower temperature working fluid in a liquid state contained in the preheater (28).