Volumetric Expander Pump for Low-Temp Thermal Energy Conversion
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Solution Overview
Problem
Existing thermal energy conversion systems, such as turbines and volumetric expanders, are inefficient and costly for medium/low-temperature heat sources, require external power for fluid pumping, and suffer from cavitation and maintenance issues.
Innovation Solution
A closed-loop Rankine cycle system using a volumetric expander and a novel pump design with synchronized compartments to efficiently convert thermal energy into mechanical and electrical energy, minimizing external power consumption and reducing cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If turbines are used for thermal energy conversion, then high power output can be achieved, but the system becomes unsuitable for medium/low-temperature heat sources and requires very high temperatures and gaseous working fluid
Solution Approach 1:
The patent changes the working parameters from high-temperature gaseous fluid required by turbines to liquid working fluid at medium/low temperatures (35-90°C) suitable for volumetric expanders. This parameter change enables the system to adapt to medium/low-temperature heat sources while maintaining power generation capability
Solution Approach 2:
The patent replaces the turbine mechanism with a volumetric expander that copies the essential function of thermal energy conversion but is specifically designed for liquid working fluids at lower temperatures, making the system adaptable to different heat source conditions
2Ease of operation
If conventional pumps are used to circulate working fluid, then fluid circulation can be achieved, but the system suffers from cavitation problems, leakage at high pressure, and poor efficiency
Solution Approach 1:
The pump is driven by the high-pressure working fluid from the expander itself, making the system self-sufficient and eliminating the need for external power sources. This self-service approach reduces complexity and improves reliability by removing external dependencies
Solution Approach 2:
The patent employs a positive displacement pump design that uses the hydraulic pressure from the expander to drive the pumping action, leveraging fluid mechanics principles to achieve reliable circulation without cavitation or leakage problems
3Use of energy by moving object
If multi-head pistons are used in the pump, then a self-sustaining cycle can be achieved with minimal external power, but the device complexity increases
Solution Approach 1:
The patent merges multiple pump functions into a single multi-head piston device where one piston drives multiple pumping compartments. This combining approach achieves the self-sustaining cycle function while reducing the number of separate components compared to using multiple independent pumps
Solution Approach 2:
The multi-head piston serves multiple functions simultaneously: it acts as both the expander output receiver and the driver for multiple pumping compartments, creating a universal component that enables the self-sustaining cycle without requiring separate dedicated devices for each function
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 achieves high efficiency and cost-effectiveness in converting thermal energy from medium/low-temperature sources with reduced maintenance and assembly costs, while operating with both liquid and gaseous working fluids.
Implementation Method 1
a working fluid performs a thermodynamic cycle... for the generation of electrical and/or mechanical power by the recovery and conversion of heat from a hot source
Implementation Method 2
particularly hot sources in which a liquid (typically water) is present at temperatures below 100 °C
Implementation Method 3
the working fluid performs a thermodynamic cycle, specifically a closed thermodynamic cycle, e.g., a Rankine cycle
Implementation Method 4
Plants employing piston, screw, scroll volumetric expanders or reactive expanders such as gas turbines are known to recover thermal energy and subsequently produce electricity
Implementation Method 5
DE 102015224416 A1, WO 2016/144233 A1 and DE 102016113007 A1 disclose plants where condensate produced at the outlet of a condenser is returned back to the inlet of a steam generator or evaporator
Data Source
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AI summary
The present invention relates to a process and plant (1) for converting thermal energy into electrical and/or mechanical energy. The plant includes a closed circuit (2), a pump (13) to circulate the working fluid in the closed circuit (2), an evaporator (3) to heat the working fluid to cause it to change from a liquid to a gaseous state, a volumetric expander (4) operating in the closed circuit (2) downstream of the evaporator (3) and configured to receive working as an input fluid in the gaseous state, a condenser (16) operating on the closed circuit (2) downstream of the volumetric expander (4) and upstream of the pump (13) to condense the working fluid determining its transition from the gaseous to the liquid state. The pump (13) in turn comprises a first compartment positionable in fluid communication with a first portion (2a) of the closed circuit (2), extending downstream of the pump (13) and upstream of the evaporator (3), to send working fluid in the liquid state to the same evaporator (3), and a second compartment that may be positioned in fluid communication with a second portion (2b) of the closed circuit, extending upstream of the volumetric expander (4) and downstream of said first portion (2a), to receive working fluid in the gaseous state generated by the evaporator (3). The working fluid in the gaseous state expands the second compartment and causes a volume reduction of the first compartment by promoting the pumping of the working fluid in the liquid state to the evaporator (3).