Metal Hydride Heat Pump Regeneration With Exhaust Gas Recirculation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional metal hydride heat pumps face inefficiencies due to overheating of heat transfer surfaces, high thermal inertia, reduced cooling capacity, and reliability issues caused by direct use of high-temperature exhaust gases, leading to clogging and material degradation, which complicates the system and increases costs.
Innovation Solution
A regeneration system for metal hydride heat pumps that recirculates exhaust gases to reduce inlet temperature to 100-250°C, improving heat transfer efficiency, reducing thermal inertia, and incorporating a self-cleaning mechanism to prevent dust and soot deposition, using a fluid recirculation circuit with a mixer and flow regulators to manage gas flow and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-temperature exhaust gases (500-600°C) are used directly in the metal hydride heat pump, then heat recovery efficiency is improved, but heat transfer surfaces overheat and thermal inertia increases
Solution Approach 1:
The patent introduces a heat transfer fluid (water or glycol mixture) as an intermediary between the exhaust gas and the metal hydride reactor. The fluid absorbs heat from the exhaust gas in a heat exchanger and then transfers it to the reactor, preventing direct contact between high-temperature exhaust and the heat transfer surfaces. This mediator approach allows efficient heat recovery while maintaining surface temperatures within safe limits.
2Use of energy by moving object
If high-temperature exhaust gases are used directly, then heat recovery is enhanced, but thermal inertia of metal hydride increases reducing cooling capacity
Solution Approach 1:
The heat transfer fluid acts as a buffer that controls the rate of heat transfer to the metal hydride. By regulating the fluid flow rate and temperature, the system can absorb heat efficiently during the charging phase while preventing excessive temperature rise that would increase thermal inertia and reduce subsequent cooling capacity.
3Temperature
If exhaust gases are cooled below 250°C, then heat transfer efficiency improves, but condensation and deposits occur clogging the heat exchanger
Solution Approach 1:
The patent converts the harmful condensation and deposit formation into a beneficial self-cleaning mechanism. By allowing the heat exchanger surfaces to cool down periodically and then exposing them to high-velocity exhaust gas flows, accumulated deposits are burned off or dislodged, maintaining heat transfer efficiency and preventing clogging.
4Duration of action of stationary object
If exhaust gases are recirculated to reduce inlet temperature, then thermal stress is reduced and component life is extended, but system complexity increases
Solution Approach 1:
The recirculated heat transfer fluid serves multiple functions: it cools the exhaust gas to prevent overheating, preheats the incoming fluid to improve heat transfer efficiency, and provides flow regulation to manage thermal stress. This multi-functionality reduces the need for additional separate systems, thereby limiting the increase in overall system complexity.
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 enhances cooling capacity, coefficient of performance, and reliability by reducing thermal stress, extending the life of components, and allowing the use of cost-effective materials, while maintaining efficient heat transfer and self-cleaning capabilities.
Implementation Method 1
In a typical metal hydride heat pump, hydrogen is used as the refrigerant material while a metal hydride alloy acts as the sorbent media
Implementation Method 2
The exhaust gas is cooled by the sorbent media, i.e., the metal hydride alloy
Implementation Method 3
The exhaust gas stream passes through a plurality of passes 5 and a number of flow reversals 6 to achieve a better heat transfer rate
Implementation Method 4
The recirculation stream is mixed with the exhaust stream in a mixer to provide a resultant stream having a temperature which is intermediate of the temperature of the exhaust stream and the temperature of the recirculation stream
Data Source
AI summary
Envisaged is a regeneration system for a metal hydride heat pump of a damper type. The system comprises a plurality of reactor assembly modules configured to act as a heat pump, an ambient air inlet and a fluid recirculation circuit. The plurality of reactor assembly modules includes first, second, third and fourth metal hydride reactor assembly modules. The fluid recirculation circuit comprises a mixer, a fluid stream switching means, a flow regulating means and an exhaust outlet. The mixer is adapted to mix a portion of a recirculation stream received from the exhaust outlet and the exhaust gas stream to provide a resultant stream. The fluid stream switching means is coupled to the mixer and is adapted to switch flow of the resultant stream as received from the mixer and the ambient air stream in a cyclic manner in a series of half-cycles of operation.