Floating OTEC Plant with Multi-Stage Heat Exchange for Lower Parasitic Load
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Solution Overview
Problem
Ocean Thermal Energy Conversion (OTEC) power plants face low thermodynamic efficiency, high parasitic loads, and environmental concerns due to the limited temperature difference between warm and cold seawater, leading to increased construction and operating costs, as well as environmental impact.
Innovation Solution
A floating OTEC power plant with a multi-stage heat engine and integrated heat exchange system, featuring a continuous offset staved cold water pipe and modular design, which reduces parasitic loads, construction costs, and environmental footprint by optimizing heat transfer and water flow, and discharging waste water at appropriate depths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If large heat exchange surface areas and high fluid velocities are used to maximize heat transfer, then heat transfer efficiency is improved, but parasitic load increases and net efficiency decreases
Solution Approach 1:
The patent changes the physical parameters of the heat exchanger by incorporating phase change mechanisms (evaporation and condensation) that dramatically increase heat transfer coefficients. This allows achieving the required heat transfer with smaller surface areas and lower fluid velocities, thereby reducing parasitic pumping loads while maintaining or improving heat transfer efficiency.
Solution Approach 2:
The invention utilizes phase transitions of the working fluid (evaporation in the evaporator and condensation in the condenser) to maximize heat transfer. During phase change, the working fluid absorbs or releases large amounts of latent heat at constant temperature, enabling highly efficient heat exchange with minimal temperature difference and reduced heat exchanger size, thus lowering parasitic energy consumption.
2Productivity
If OTEC power plants are built to generate electrical energy, then renewable energy production is achieved, but low thermodynamic efficiency makes them commercially non-viable
Solution Approach 1:
The patent optimizes thermodynamic parameters including working fluid selection (using refrigerants with appropriate boiling points), evaporator pressure and temperature, condenser temperature, and turbine expansion ratios. These parameter optimizations maximize the Carnot efficiency of the heat engine cycle, improving net electrical energy generation while minimizing energy losses.
Solution Approach 2:
The invention employs a closed-cycle heat engine utilizing phase transitions of the working fluid to convert thermal energy to mechanical work. The working fluid evaporates in the evaporator driven by warm ocean water, expands through a turbine to generate electricity, then condenses in the condenser using cold ocean water, completing the cycle. This phase-change-based heat engine achieves superior thermodynamic efficiency compared to direct thermal conversion methods.
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 enhances overall efficiency, reduces construction and operating costs, and minimizes environmental impact by improving heat transfer efficiency and reducing pressure losses, while maintaining reliable and sustainable energy production.
Implementation Method 1
uses the temperature difference between surface and deep sea tropical waters to drive a heat engine to produce electrical energy
Implementation Method 2
drive a heat engine to produce electrical energy
Implementation Method 3
efficient heat transfer between the warm sea water and the working fluid, and between the cold sea water and the working fluid
Data Source
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AI summary
An offshore power generation structure comprising a submerged portion having a first deck portion comprising an integral multi-stage evaporator system, a second deck portion comprising an integral multi-stage condensing system, a third deck portion housing power generation equipment, cold water pipe; and a cold water pipe connection.