Adsorption Compressor Thermal Wave Cycling for Compact Heat Pumps
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Solution Overview
Problem
Existing adsorption heat pump systems using zeolite as adsorbents are bulky due to low operating pressures, limiting specific cooling power (SCP) and coefficient of performance (COP), and require large condenser and evaporator sizes.
Innovation Solution
A method and system for operating an adsorption compressor with a thermal wave cycle split into four phases, where heat transfer fluid (HTF) flow direction is reversed to maintain a steep thermal wave, allowing more refrigerant adsorption and desorption, and using optimized dimensions for adsorption material and HTF channels to enhance SCP while maintaining high COP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water is used as refrigerant in adsorption heat pump systems operating at reduced pressures, then the system is environmentally friendly and safe, but the specific cooling power (SCP) is lowered and the system becomes bulky in size
Solution Approach 1:
The patent changes the operating pressure parameter from reduced pressure to elevated pressure (above atmospheric pressure). This allows the use of water as refrigerant while achieving higher density and faster adsorption/desorption kinetics, thereby reducing system size and increasing SCP while maintaining environmental benefits
Solution Approach 2:
The patent introduces a moving thermal wave through the adsorption bed by dynamically controlling the temperature profile. This creates continuous cyclic adsorption and desorption zones that move through the bed, enabling rapid refrigerant mass transfer and high SCP without requiring large system volumes
2Productivity
If a thermal wave is applied to increase refrigerant mass flow and SCP, then the cooling power is enhanced, but the system complexity and control difficulty increase
Solution Approach 1:
The patent employs periodic heating and cooling of the adsorption bed to generate a traveling thermal wave. The heating/cooling process is cyclically applied at different positions along the bed, creating regular waves that drive continuous adsorption-desorption cycles and maintain high refrigerant mass flow
Solution Approach 2:
The patent uses temperature sensors distributed along the adsorption bed to detect the position and shape of the thermal wave. This feedback information is used by the control system to adjust heating/cooling power and timing, maintaining optimal thermal wave profiles and compensating for disturbances to preserve high productivity
3Ease of operation
If batch heating and cooling of adsorption material is used, then the system operation is simple, but the heat pump performance and efficiency are reduced
Solution Approach 1:
The patent transitions from static batch heating/cooling to dynamic thermal wave operation. The thermal wave continuously moves through the adsorption bed, creating alternating zones of adsorption and desorption that occur simultaneously throughout the bed. This dynamic operation dramatically improves heat pump performance and efficiency while maintaining operational simplicity through automated control
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 improved SCP and COP, reducing the size of the heat pump and compressor, making it more efficient and economical, with a compact design and high thermodynamic efficiency.
Implementation Method 1
heating the first adsorption bed by feeding heat transfer fluid to it, coming from the second adsorption bed, while maintaining a thermal wave in the first adsorption bed; and cooling the second adsorption bed by feeding heat transfer fluid to it, coming from the first adsorption bed, while maintaining a thermal wave in the second adsorption bed
Implementation Method 2
heat is circulated using a heat transfer fluid (HTF)
Implementation Method 3
heating the first adsorption bed by feeding heat transfer fluid to it... cooling the second adsorption bed by feeding heat transfer fluid to it
Implementation Method 4
The beds in U.S. Pat. No. 4,610,148 comprise a zeolite, and the applied refrigerant or adsorbing vapor is water
Implementation Method 5
The adsorbing vapor is forced out of the solid adsorption material by heating the material with a heat transfer fluid
Implementation Method 6
the water vapor originating from the adsorption beds is guided through a set of check valves to a condenser of a heat pump. There the water vapor is condensed in a high pressure condenser
Implementation Method 7
the condensed water is guided through a pressure release valve, where due to the Joules Thomson effect, the temperature decreases substantially adiabatically
Implementation Method 8
In a low pressure evaporator, the water is re-evaporated and can be returned through a set of check valves to that adsorption bed that is cold and accepting the vapor to adsorb. The evaporator provides the actual thermal cooling power of the heat pump
Data Source
AI summary
The present invention is directed to a method of operating an adsorption compressor system, which system comprises a hot source and a cold source and at least a first and a second adsorption bed, wherein the first bed has an initial temperature that is lower than the initial temperature of said second bed, in which system heat is circulated using a heat transfer fluid (HTF), the method comprising the following phases:phase A) comprising the steps of:heating the first adsorption bed by feeding HTF to it, coming from said second bed, optionally via said hot source, while maintaining a thermal wave in said first bed; andcooling the second adsorption bed by feeding HTF to it, coming from said first bed, optionally via said cold source, while maintaining a thermal wave in said second bed; wherein phase A) is maintained until the exit temperature of said first bed and said second bed are essentially the sameand phase B) comprising the steps of:feeding the HTF effluent of said first bed to said hot source and from said hot source back into said first bed; andfeeding the HTF effluent of said second bed to said cold source and from said cold source back into said second bed; wherein phase B) is maintained until the temperature in said first bed is essentially homogeneous and the temperature in said second bed is also essentially homogeneous and lower than the temperature of said first bed, wherein the flow rates of said HTF through said first and second bed may be higher than in phase A).