Combined vapor absorption and mechanical compression cycle design
Solution Overview
Problem
Conventional HVAC&R systems face inefficiencies due to reliance on mechanical compression, high costs from solar power stabilization, and low collection efficiency in solar thermal absorption chillers, leading to wasted thermal energy and increased system costs.
Innovation Solution
An integrated refrigeration system combining vapor compression and absorption refrigeration cycles, where the absorption refrigeration cycle is fluidly coupled with the vapor compression cycle, utilizing a low-power pump and external heat sources like solar power to enhance efficiency, with an absorber configured as a liquid-liquid mixer and heat exchangers to optimize heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If solar thermal collectors with high temperature lift are used to drive absorption chillers, then the refrigeration system can be powered by solar energy, but the collection efficiency is low
Solution Approach 1:
The system divides the refrigeration load into two segments: base load handled by the absorption chiller using low-temperature solar thermal energy, and peak load handled by the vapor compression chiller. This segmentation allows the absorption chiller to operate efficiently at its designed temperature range while meeting overall refrigeration requirements.
Solution Approach 2:
The patent merges two different refrigeration technologies (absorption and vapor compression) into a single hybrid system. The absorption chiller uses solar thermal energy for base load, while the vapor compression chiller supplements during peak demand, combining the advantages of both systems to overcome the limitations of each individually.
2Use of energy by moving object
If photo voltaic systems are used to power the refrigeration system, then solar energy can be utilized, but additional components are required resulting in high system cost
Solution Approach 1:
The patent replaces the electrical-to-mechanical conversion path (photovoltaic panels → power electronics → compressor motor) with a direct thermal-to-refrigeration path (solar thermal collectors → absorption refrigeration cycle). This substitution eliminates the need for power electronics, electricity storage, and complex voltage stabilization components, reducing system cost and complexity.
3Use of energy by moving object
If conventional absorption chillers are used with solar thermal collectors, then solar energy can drive the refrigeration system, but the current commercially available absorption chillers require high temperature lift resulting in low collection efficiency
Solution Approach 1:
The patent changes the operating temperature parameters of the absorption chiller to match the output characteristics of flat plate solar thermal collectors (lower temperature range). By adjusting the refrigerant-absorbent pair and cycle parameters, the system achieves efficient operation at the lower temperatures that high-efficiency solar collectors can provide, rather than requiring high temperature lift.
Solution Approach 2:
The system is designed to self-match the solar collector output characteristics with the absorption chiller input requirements. The thermal output of standard efficiency flat plate collectors directly matches the input requirements of the modified absorption cycle, eliminating the need for intermediate temperature conversion or specialized high-temperature collectors.
4Power
If shaft power from internal combustion engine is used in refrigeration systems, then the refrigeration system can be powered, but thermal energy from engine exhaust and coolant is wasted
Solution Approach 1:
The patent converts the waste thermal energy from engine exhaust and coolant into a useful resource by directing it to drive the absorption chiller. The previously discarded low-grade thermal energy now serves as the heat source for refrigeration, transforming an energy loss into a beneficial contribution to the overall system performance.
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
This integrated system increases fuel efficiency, reduces component sizes, and lowers operating costs by leveraging thermal energy and renewable energy sources, achieving improved overall efficiency and cost-effectiveness in HVAC&R applications.
Implementation Method 1
The gas is first absorbed by an absorbing liquid and the liquid mixture is subsequently heated by an external heat source
Implementation Method 2
the liquid mixture is subsequently heated by an external heat source to generate a hot gas at an elevated pressure
Implementation Method 3
The hot gas is then condensed back to a liquid when cooled
Implementation Method 4
condenses the hot, high pressure gas back to a liquid by heat exchange with a cool fluid, such as air or water
Implementation Method 5
a first heat exchanger is arranged generally downstream from the compressor and generally upstream from the desorber, the first heat exchanger being configured to transfer heat between the refrigerant and the mixture such that the refrigerant supplied to the absorber condenses to a liquid
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A refrigeration system is provided including a vapor compression cycle (20) having a condenser (22), and expansion valve (24), and evaporator (26) and a compressor (28). A refrigerant is configured to circulate through the vapor compression cycle. The refrigeration system also includes an absorption refrigeration cycle (30) having an absorber (32) and a desorbed (34) arranged in a generally closed loop configuration. An absorption solution is configured to circulate through the absorption refrigeration cycle. The vapor compression cycle and the absorption refrigeration cycle are substantially integrated. The absorber is fluidly coupled to the compressor and is configured to generate a mixture of refrigerant and absorption solution. The desorber is fluidly coupled to the condenser and is configured to separate the refrigerant from the mixture and increase a pressure of the refrigerant vapor.