Dual-Fluid Heat Exchanger With Recirculation for Stable Outlet Temperature
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Solution Overview
Problem
Conventional heat exchange systems face challenges in maintaining a consistent output temperature of the warmed fluid, leading to inefficiencies and regulatory issues due to varying flow rates and high steam temperatures, while also occupying excessive space and requiring unnecessary components like condensate pumps and pressure regulating valves.
Innovation Solution
A dual fluid heat exchange system with a re-circulation loop that stabilizes the output temperature by recirculating fluid directly into a mid-portion of the tank, allowing for controlled condensation of steam to enhance heat transfer and reduce the temperature of the cooled fluid, eliminating the need for certain valves and pumps, and optimizing the tank structure for minimal footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the flow rate of steam is increased to meet higher heating demand, then the heating capacity is improved, but the output temperature of the warmed fluid becomes unstable and varies significantly
Solution Approach 1:
The system employs a temperature sensor to continuously monitor the output temperature of the warmed fluid and feeds this information back to a control valve. The control valve automatically adjusts the steam flow rate based on the temperature feedback, maintaining stable output temperature even when heating demand varies. This closed-loop control system resolves the contradiction by enabling dynamic adjustment that preserves both heating capacity and temperature stability.
Solution Approach 2:
The system transitions from a static, manually adjusted heat exchanger to a dynamic system with automatic control. The control valve responds in real-time to changing conditions, allowing the system to adapt its steam flow rate dynamically. This dynamic adjustment capability enables the system to maintain stable output temperature while meeting varying heating demands, resolving the contradiction between productivity and stability.
2Stability of the object's composition
If conventional temperature stabilization methods are used by adjusting cooled fluid flow rate, then the warmed fluid output temperature is stabilized, but the cooled fluid temperature varies drastically reducing energy efficiency
Solution Approach 1:
The system changes the control parameter from cooled fluid flow rate to steam flow rate. By controlling the heat input (steam flow) rather than the cooled fluid flow, the system stabilizes output temperature while maintaining more consistent cooled fluid temperature. This parameter change enables better energy efficiency because the cooled fluid retains more of its thermal energy, reducing the need to reheat it and thereby reducing energy loss.
3Productivity
If large horizontal heat exchangers are used to provide sufficient heating capacity, then the heating performance is improved, but the floor space requirement increases significantly
Solution Approach 1:
The system transitions from a horizontal heat exchanger configuration to a vertical orientation. By standing the heat exchanger on its end, the system utilizes vertical space instead of horizontal floor space. This dimensional change allows the same heating capacity to be achieved within a much smaller footprint, resolving the contradiction between productivity and space utilization. The control system further enhances this by optimizing heat transfer efficiency, ensuring adequate heating performance in the compact vertical configuration.
4Use of energy by moving object
If high temperature steam is used for heating, then the heating efficiency is improved, but the temperature of the cooled fluid leaving the system becomes too high causing thermal pollution and regulatory issues
Solution Approach 1:
The system changes the control approach from adjusting cooled fluid flow rate to controlling steam flow rate and condensation. By controlling the heat input parameter (steam flow) and utilizing condensation heat transfer, the system achieves high heating efficiency while maintaining better control over the cooled fluid outlet temperature. This prevents thermal pollution by ensuring the discharged fluid meets temperature regulations, resolving the contradiction between energy efficiency and environmental compliance.
Solution Approach 2:
The system utilizes the phase transition of steam condensing into water as the primary heat transfer mechanism. This phase change process releases large amounts of latent heat efficiently, improving heating efficiency. Simultaneously, the condensation process provides precise control over heat transfer, enabling the system to maintain the cooled fluid outlet temperature within regulatory limits and prevent thermal pollution, thus resolving the contradiction.
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 stable output temperatures within ±3° F, increases energy efficiency by extracting heat from the cooled fluid, and reduces the temperature of the steam condensate, minimizing waste and space requirements while eliminating unnecessary components.
Implementation Method 1
steam condensing in the tank heats the water
Implementation Method 2
steam circulates in the second fluid circuit... where the cool water is warmed by flowing over thermally conductive conduits containing the high temperature steam
Implementation Method 3
a re-circulation loop... such that the re-circulated fluid flow primarily warms only a re-circulation section of the tank
Data Source
AI summary
A dual fluid heat exchange system is presented that provides a stable output temperature for a heated fluid while minimizing the output temperature of a cooled fluid. The heated and cooled fluids are brought into thermal contact with each other within a tank. The output temperature of the warmed fluid is maintained at a stable temperature by a re-circulation loop that connects directly to the mid portion of the tank such that the re-circulated fluid flow primarily warms only a re-circulation section of the tank. The other, lower flow rate, section of the tank may be positioned so that it has a cooler temperature and thus serves to increase the efficiency of the heat exchange by extracting extra heat energy out of the cooled fluid before it leaves the tank. Alternatively, the low flow rate section of the tank may be warmer than the re-circulated section, and thus allow the re-circulated section to be cooler than the output temperature of the warmed fluid.