Cooling systems and methods incorporating a plural in-series pumped liquid refrigerant trim evaporator cycle
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Solution Overview
Problem
Conventional cooling systems are inefficient under varying load conditions and in diverse environmental settings, leading to increased energy consumption and maintenance costs, particularly in low-loading and high-latent environments, due to limitations in compressor control and refrigerant system performance.
Innovation Solution
A dual pumped liquid refrigerant system with primary and secondary evaporator coils and corresponding distribution units, where the trim compression cycle is activated when the temperature exceeds a predetermined threshold, allowing incremental cooling adjustments based on environmental conditions, reducing compressor load and energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional cooling systems operate under low-loading conditions, then cooling capacity is reduced, but energy consumption per ton of cooling increases dramatically
Solution Approach 1:
The system divides the cooling function into multiple independent evaporator coils (first, second, and optional third evaporators) that can operate independently or in combination. This segmentation allows the system to provide precise partial loading capability by activating only the necessary number of evaporators, thereby maintaining high efficiency even at reduced cooling capacities.
Solution Approach 2:
The system employs dynamic control of multiple evaporators and compressors that can be independently activated or deactivated based on real-time cooling demands. This dynamic configuration allows the system to adapt its capacity continuously, avoiding the efficiency penalties associated with conventional systems operating far below their rated capacity.
2Measurement precision
If metering devices are used to control refrigerant flow in evaporators, then tight control of vapor evaporation is achieved, but liquid slugging to the compressor occurs under low loading conditions
Solution Approach 1:
The system divides the refrigerant distribution into multiple independent evaporator circuits, each with its own refrigerant inlet. This segmentation allows better control of refrigerant flow distribution and reduces the risk of liquid slugging by ensuring that each evaporator receives appropriate refrigerant quantities independent of overall system loading conditions.
Solution Approach 2:
The system introduces intermediate refrigerant distribution manifolds and multiple inlet points to evaporators, acting as intermediaries that balance refrigerant flow distribution. These intermediaries help prevent liquid carryover to compressors by providing additional flow path control and pressure equalization points.
3Reliability
If hot gas bypass and low ambient kits are installed to mitigate slugging and uneven heat distribution, then compressor protection is improved, but energy consumption increases
Solution Approach 1:
The system uses multiple independent evaporator coils with separate refrigerant distribution, eliminating the need for hot gas bypass valves and low ambient kits. Each evaporator can be independently controlled to maintain proper refrigerant flow and heat distribution without requiring energy-consuming protective devices.
Solution Approach 2:
The system achieves self-protection against liquid slugging through its inherent multi-evaporator design with independent refrigerant distribution. The system naturally prevents uneven heat distribution and compressor slugging through proper refrigerant flow management, eliminating the need for additional protective equipment that would increase energy consumption.
4Productivity
If air-cooled direct expansion systems are used in high dry bulb ambient conditions, then cooling capacity is maintained, but kw per ton exceeds 1.0
Solution Approach 1:
The system divides the cooling load across multiple evaporator coils with independent refrigerant distribution, allowing optimized heat transfer surface area utilization. This segmentation enables the system to maintain high cooling capacity in high ambient conditions while operating at lower power consumption per ton through improved thermal efficiency.
Solution Approach 2:
The system optimizes refrigerant flow parameters and heat transfer parameters across multiple evaporators to maintain high efficiency in high ambient temperature conditions. By adjusting refrigerant distribution and evaporator operation parameters, the system achieves better than 1.0 kw/ton performance even in challenging environmental conditions.
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 a significant reduction in energy consumption by up to 90% compared to conventional chiller plants, improving cooling efficiency across a broad spectrum of loading conditions and environmental factors, with reduced maintenance costs.
Implementation Method 1
first evaporator coil in thermal communication with an air intake flow to a heat load
Implementation Method 2
first evaporator coil in thermal communication with an air intake flow to a heat load
Implementation Method 3
the expanded liquid absorbs the heat present in the evaporator coil
Implementation Method 4
The expanded liquid absorbs the heat present in the evaporator coil and leaves the coil as a super-heated vapor
Implementation Method 5
a fluid cooler for free cooling a first fluid circulating through the first and second liquid refrigerant distribution units
Data Source
AI summary
Systems and methods relating to a plural in-series pumped liquid refrigerant trim evaporator cycle are described. The cooling systems include a first evaporator coil in thermal communication with an air intake flow to a heat load, and a first liquid refrigerant distribution unit in thermal communication with the first evaporator coil. The cooling systems further include a second evaporator coil disposed in series with the first evaporator coil in the air intake flow and in thermal communication with the air intake flow, and a second liquid refrigerant distribution unit in thermal communication with the second evaporator coil. A trim compression cycle of the second liquid refrigerant distribution unit is configured to further cool the air intake flow through the second evaporator coil when the temperature of the first fluid flowing out of the main compressor of the second liquid refrigerant distribution unit exceeds a predetermined threshold temperature.