Co-fired absorption system generator
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing firetube-based generator systems in ammonia-based absorption cooling systems have limitations in heat transfer efficiency due to reliance on a single heat source, which can lead to increased energy requirements and reduced performance.
Innovation Solution
A co-fired generator system is enhanced by incorporating a secondary cylindrical heat exchanger that surrounds the firetube, providing dual-sided heating through an annulus with additional fin assemblies, allowing for increased heat transfer efficiency and the use of multiple heat sources, such as solar collectors or engine exhaust, to reduce energy input requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single firetube heat source is used, then the system structure is simple, but the heat transfer efficiency is insufficient
Solution Approach 1:
The patent combines a firetube heat exchanger and a shell-and-tube heat exchanger into a single integrated generator system. The firetube provides internal heating while the shell-and-tube heat exchanger surrounds it to provide external heating, merging two heat transfer mechanisms into one unified system to achieve dual-sided heating and improved overall efficiency
Solution Approach 2:
The shell-and-tube heat exchanger is nested around the firetube heat exchanger, creating a concentric configuration where the annulus chamber contains the firetube. This nested arrangement allows both heat exchangers to occupy the same spatial envelope, enabling dual-sided heating without significantly increasing the overall system footprint
2Use of energy by moving object
If a single heat source is used, then the energy input is sufficient for operation, but the energy requirements are high
Solution Approach 1:
The system merges multiple heat sources (firetube combustion and external shell-and-tube heating) to provide combined thermal energy input. This allows the system to achieve the required heating effect with lower individual energy inputs from each source, reducing overall energy requirements while maintaining sufficient energy input for operation
3Productivity
If dual-sided heating is implemented, then the heat transfer efficiency increases, but the device complexity increases
Solution Approach 1:
The shell-and-tube heat exchanger is nested around the firetube in a concentric arrangement, utilizing the same cylindrical space efficiently. This nested configuration implements dual-sided heating while minimizing the increase in overall system complexity and footprint, as both heat exchangers share the same spatial envelope
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 dual-sided heating configuration increases the overall heat transfer efficiency of the system, reducing the energy needed for the firetube to achieve target temperatures and enabling more efficient operation of ammonia-based absorption cooling systems.
Implementation Method 1
The heat of the gas is transferred through the walls of the firetube by thermal conduction, and then heating the liquid, usually to its boiling point
Implementation Method 2
One known type of firetube has a cylindrical chamber with fins secured to the interior surface of the cylinder to increase the internal surface area. The hot gas heats the fins from both sides and also heats the cylinder. The fins, being in contact with the cylinder, transfer their heat to the cylinder
Implementation Method 3
This heating produces bubbles of ammonia gas and water vapor
Implementation Method 4
nearly pure ammonia vapor can pass to a condenser where it is cooled and condenses into liquid ammonia
Implementation Method 5
From there, the two phase, but mostly liquid, and nearly pure ammonia enters an evaporator, where heat transfer from a chilled heat transfer fluid, such as water or a brine, causes the ammonia to evaporate. The evaporation of the ammonia causes the desired cooling or refrigeration
Implementation Method 6
In the absorber, the ammonia is absorbed out of the gas mixture into the weak water-ammonia solution, resulting in a strong water-ammonia solution
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A co-fired generator for use in a continuous-cycle absorption heating and cooling system may provide heat to the interior of an annulus chamber from a first heat exchanger, such as a firetube heat exchanger, supplemented by heat to the exterior of the annulus chamber from a second heat exchanger containing fluid heated by an external source. Some embodiments may circulate fluid heated in a solar-heated collector through the second heat exchanger. Other embodiments may route exhaust gas from a combustion engine through the second heat exchanger. The second heat exchanger may be provided with a plurality of fins to increase the surface area available for thermal transfer between the heated fluid and the annulus chamber.