Low-Grade Heat Air Conditioning for Separate Temperature-Humidity Processing
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Solution Overview
Problem
Conventional air-conditioning systems face challenges in efficiently utilizing low-grade heat sources at 80° C. or lower temperatures for absorption refrigeration, as they require higher temperatures for effective cooling and dehumidification, and existing systems cannot effectively utilize lithium chloride (LiCl) as an absorption working medium pair due to its physical properties.
Innovation Solution
A low-grade heat driven temperature and humidity separately processed air-conditioning system is developed, incorporating an absorption refrigeration circulation loop, a solution dehumidification-regeneration circulation loop, and a cooling water circulation loop, which utilizes lithium chloride (LiCl) as the absorption working medium pair, allowing for efficient processing of air temperature and humidity using low-grade heat energy at 80° C. or lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single-stage single-effect lithium bromide absorption refrigeration systems are used, then air conditioning performance is favorable, but the heat source temperature must be 90-120°C which limits utilization of low-grade heat sources
Solution Approach 1:
The patent divides the absorption refrigeration process into two stages: a first-stage absorber for initial refrigerant absorption and a second-stage absorber for further absorption at lower temperatures. This segmentation enables the system to utilize low-grade heat sources at 80°C or lower while maintaining effective refrigeration performance, as each stage operates at optimized temperature levels suitable for low-temperature heat utilization.
Solution Approach 2:
The patent changes the working parameters by using lithium chloride (LiCl) instead of conventional lithium bromide (LiBr) as the absorption medium. LiCl allows operation at lower heat source temperatures (80°C or lower) while maintaining effective absorption refrigeration. This parameter change enables utilization of low-grade heat sources that were previously insufficient for absorption refrigeration systems.
2Temperature
If two-stage absorption refrigeration system is used to produce cooling capacity at lower temperature, then heat source temperature can be decreased, but the performance coefficient drops to approximately half of conventional single-effect circulation
Solution Approach 1:
The patent implements a two-stage absorption system where the first-stage absorber handles the primary refrigerant absorption and the second-stage absorber provides additional absorption capacity. This segmentation allows the system to operate with low-grade heat sources at 80°C or lower while maintaining high performance coefficients, avoiding the 50% efficiency loss of conventional two-stage systems by optimizing the distribution of absorption functions across stages.
Solution Approach 2:
By changing from lithium bromide to lithium chloride as the absorption medium, the patent enables operation at lower temperatures with improved thermodynamic performance. LiCl's properties allow the two-stage system to maintain high performance coefficients even at reduced heat source temperatures, unlike conventional systems that suffer efficiency penalties.
3Temperature
If conventional lithium bromide absorption refrigeration system is used, then cooling capacity of about 5°C can be produced, but lithium chloride cannot meet the requirement due to its physical properties
Solution Approach 1:
The patent successfully changes the working medium from lithium bromide to lithium chloride, overcoming LiCl's traditional limitations. By adjusting system parameters and implementing a two-stage absorption configuration, the patent enables LiCl to produce the required cooling capacity while maintaining system reliability. This parameter change allows utilization of low-grade heat sources with improved thermodynamic performance.
4Ease of operation
If conventional all-air conditioning systems use condensation dehumidification, then air temperature and humidity can be processed, but the cold source temperature required for cooling is apparently higher than for dehumidification
Solution Approach 1:
The patent separates temperature processing and humidity processing into independent functional components. The absorption refrigeration system handles cooling while a separate dehumidification system manages moisture removal. This segmentation allows each subsystem to operate at optimized temperature levels, with the dehumidification system requiring lower cold source temperatures than conventional combined systems.
Solution Approach 2:
The patent introduces a liquid desiccant as an intermediary medium for dehumidification. This liquid desiccant absorbs moisture from air through mass transfer rather than requiring low-temperature cooling surfaces. This intermediary approach enables effective dehumidification with higher cold source temperatures, resolving the temperature conflict between cooling and dehumidification requirements.
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 system effectively utilizes low-grade heat energy to achieve efficient cooling and dehumidification, improving energy efficiency and allowing the use of LiCl—H2O as a working medium pair, which offers superior thermodynamic performance compared to conventional lithium bromide systems, enabling seamless integration with existing heat collectors and ensuring high indoor air quality by maintaining air conditioning units in a dry state.
Implementation Method 1
lithium chloride absorption refrigeration circulation loop... utilizes low-grade heat energy at 80° C. or lower temperatures to drive absorption refrigeration for air conditioning
Implementation Method 2
solution dehumidification-regeneration circulation loop... utilizes low-grade heat energy at 80° C. or lower temperatures
Implementation Method 3
an evaporator... absorbs heat from air supplied in the air supply pipeline
Implementation Method 4
the refrigerant vapor enters into a condenser, is cooled by cooling water supplied from the cooling water circulation loop, and thereby is condensed into refrigerant water
Data Source
AI summary
An independent temperature and humidity processing air conditioning system driven by low-level thermal energy, comprising an absorption-type refrigeration circulation loop, a solution dehumidification and regeneration circulation loop, a water cooling circulation loop, and a central air conditioning air supply and air return pipeline; the absorption-type refrigeration circulation loop comprises an evaporator (21), an absorber (26), a generator pump (25), a second solution heat exchanger (27), a generator (1), a condenser (2), a water-water heat exchanger (3), and a throttle valve (20); the solution dehumidification and regeneration circulation loop comprises a regenerator (8), a first solution pump (9), a solution heater (10), a first solution heat exchanger (12), a second solution pump (16), a solution cooler (17), and a dehumidifier (18); the water cooling circulation loop comprises two branches; and the central air conditioning air supply and a return pipeline comprises an air supply pipeline (13), an air return pipeline (14), an air conditioning heat exchanger (15), a dehumidifier (18), an evaporator (21), an air supply induction opening (23), an air return induction opening (22), a second flow guide fan (11), and a regenerator (8). The present air-conditioning system can resolve the problem of efficiently driving absorption-type cooling for air conditioning adjustment under 80° C.