Working fluid for a steam cycle engine
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Solution Overview
Problem
The existing steam cycle processes, particularly in organic Rankine cycles, face challenges in maintaining thermal stability and lubrication efficiency due to high temperatures and chemical reactivity, especially when used in conjunction with internal combustion engines, where the lubricant must be thermally stable and immiscible with the working medium to ensure long-term operation.
Innovation Solution
A composition of a working medium, a thermally stable hydrocarbon lubricant with a viscosity of 40 to 700 mm²/s at 40°C, and an emulsifier, such as alkenyl succinimides or alkoxylated fatty alcohols, is used, ensuring the lubricant is not soluble in the working medium to maintain viscosity and stability, with optional additives like antioxidants and anti-wear agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the lubricant is completely soluble in the working medium, then the operating fluid is homogeneous, but the viscosity of the working medium increases and lubrication efficiency deteriorates
Solution Approach 1:
An emulsifier is introduced as an intermediary substance to enable the formation of a stable emulsion between the immiscible lubricant and working medium. The emulsifier has hydrophilic and hydrophobic portions that allow it to bridge the interface between the two phases, creating a stable dispersed system where the lubricant remains immiscible but evenly distributed, thus maintaining both homogeneity and lubrication efficiency
Solution Approach 2:
The operating fluid is designed as a composite emulsion system comprising three distinct components: working medium (continuous phase), lubricant (dispersed phase), and emulsifier (interface stabilizer). This composite structure allows the system to simultaneously exhibit properties of both immiscible phases while maintaining overall stability and functionality
2Temperature
If the lubricant is thermally stable, then it can withstand high temperatures, but it becomes less miscible with the working medium
Solution Approach 1:
The emulsifier acts as a thermal-stable intermediary that maintains the emulsion structure at high temperatures. Its molecular structure is designed to remain intact under thermal stress, continuously stabilizing the interface between the thermally stable lubricant and working medium even when miscibility would naturally decrease at elevated temperatures
3Reliability
If the lubricant has high viscosity, then lubrication efficiency is improved, but the fluid dynamics in the closed circuit deteriorate
Solution Approach 1:
The lubricant is segmented into fine droplets dispersed throughout the working medium, creating a heterogeneous emulsion system. This segmentation allows the high-viscosity lubricant to be distributed in small quantities throughout the circuit, providing adequate lubrication at component interfaces while the bulk fluid maintains the low viscosity characteristics of the working medium for efficient circulation
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 solution provides a thermally and chemically stable operating fluid that maintains lubrication efficiency and viscosity, enabling long-term operation in high-temperature environments, such as heat exchangers in internal combustion engines, with effective emulsification and thermal stability demonstrated through experimental tests.
Implementation Method 1
The emulsifier is a surfactant... EP 0292526 B1 and JP 2011-063780 disclose emulsifier-containing emulsions, one phase being a water/alcohol mixture and the other phase containing heavy waxy oil or crude oil
Implementation Method 2
the lubricant should be thermally stable and largely immiscible with the working medium... the lubricant meets high requirements in terms of aging resistance... thermally stable and long-term stable
Implementation Method 3
Mechanical energy is obtained by heating and evaporating the working medium in the evaporator by supplying heat from outside
Implementation Method 4
The working medium is then cooled in the condenser, liquefied and fed back to the evaporator
Data Source
AI summary
The present invention relates to a working fluid for a steam-turbine cycle process, said fluid comprising a working medium, a lubricant and preferably an emulsifier., said The working medium is a C1 to C4 alcohol and/or a C3 to C5 ketone, optionally mixed with water. The invention also relates to a device for a steam cycle process, which device contains the working fluid, and to the use of the working fluid in an organic Rankine cycle. The lubricant is a hydrocarbon and the emulsifier is a surface-active substance.