Spray-Actuated Heat Engine for Rapid Working-Fluid Heat Transfer
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Solution Overview
Problem
Existing heat engines using Stirling, Ericsson, and Brayton cycles face inefficiencies due to boundary layer limitations and flow losses in heat exchangers, particularly in transferring energy to and from a working fluid via convection, which is slow and limited by surface area.
Innovation Solution
A spray-actuated heat engine that uses a heat transfer fluid (HTF) to alternately heat and cool an expandable volume by spray-injection, primarily through conduction, eliminating the need for surface-related convection and reducing pumping losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If heat exchangers use convection for energy transfer, then energy can be transferred to the working fluid, but the transfer rate is slow and limited by boundary layer formation
Solution Approach 1:
The patent utilizes phase transition of the heat transfer fluid from liquid to vapor through spray injection. The liquid spray droplets evaporate directly in contact with the working fluid, transferring heat through phase change rather than conventional convection. This eliminates boundary layer limitations and significantly increases energy transfer rate while reducing flow losses.
Solution Approach 2:
The patent employs hydraulic spray injection system to deliver heat transfer fluid as liquid droplets into the working fluid stream. The pneumatic-hydraulic mechanism atomizes the liquid into fine droplets, maximizing surface area for heat transfer and enabling direct contact between heat transfer medium and working fluid without conventional heat exchanger surfaces.
2Productivity
If heat exchanger surface area is enlarged to facilitate heat transfer, then energy transfer improves, but device complexity and pumping losses increase
Solution Approach 1:
The patent extracts the heat transfer function from conventional surface-based heat exchangers and implements it through direct spray injection of heat transfer fluid into the working fluid stream. This eliminates the need for complex heat exchanger surfaces, tubes, and fins, significantly simplifying device structure while maintaining or improving heat transfer efficiency.
Solution Approach 2:
The heat transfer fluid acts as an intermediary substance that carries thermal energy from the heat source to the working fluid. Instead of using solid heat exchanger surfaces as intermediaries, the patent employs a liquid spray that directly contacts both the heat source and working fluid, simplifying the heat transfer pathway and reducing structural complexity.
3Temperature
If conventional heat exchangers are used, then energy transfer occurs via conduction and convection, but the process is slow and requires large surface areas
Solution Approach 1:
The patent exploits the phase transition from liquid spray to vapor upon contact with the working fluid. This phase change occurs rapidly and releases latent heat directly into the working fluid, achieving fast temperature control without requiring large volumes of heat transfer fluid or large surface areas.
Solution Approach 2:
The spray injection system operates in periodic cycles, delivering heat transfer fluid in controlled pulses or continuous spray patterns. This periodic action allows precise control over temperature changes in the working fluid, enabling rapid response while minimizing the total quantity of heat transfer fluid required.
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 spray-actuated system achieves rapid energy transfer and increased power output by using larger surface area spray droplets, allowing for controlled temperature changes in the working fluid, thus overcoming conventional heat exchanger limitations.
Implementation Method 1
The HTF is moved to hot and cold locations where it is allowed to loiter, under pressure, and is therefore heated or cooled primarily by conduction
Implementation Method 2
The HTF is moved to hot and cold locations where it is allowed to loiter, under pressure, and is therefore heated or cooled primarily by conduction
Implementation Method 3
When sprayed into the expandable volume, energy is transferred into the working fluid by convection, but the surface area of spray droplets is much larger compared to the surface area of a heat exchanger, so the resulting energy transfer is much more rapid
Data Source
AI summary
A spray-actuated heat engine comprises an expandable volume chamber containing an operating fluid in gas form, a reservoir holding a heat transfer fluid in liquid form, a pump that pumps the heat transfer fluid from the reservoir to the chamber, and a piping system through which the heat transfer fluid is configured to flow. The piping system is in fluid communication with a heat source for heating the heat transfer fluid to obtain a high temperature and is in fluid communication with a cold source for removing heat from the heat transfer fluid to obtain a low temperature. The heat transfer fluid at the high temperature is selectively sprayed into the expandable volume to mix with and expand the operating fluid, and the heat transfer fluid at the low temperature is selectively sprayed into the expandable volume to mix with and contract the operating fluid.