Transport refrigeration unit with heat island mitigation
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Solution Overview
Problem
The efficiency of transport refrigeration units is hindered by the formation of a heat island effect around the condenser, which increases the temperature of the area between the truck and refrigerated trailer or container, making heat transfer from the refrigerant to the surrounding air more difficult.
Innovation Solution
Incorporating a refrigeration augmentation unit with a water tank and a water droplet generator to disperse water droplets onto or near the refrigerant heat rejection heat exchanger, enhancing evaporative cooling and improving heat transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the condenser is located in the area between the truck and refrigerated trailer, then the refrigeration unit can be compactly integrated, but the heat island effect increases the temperature making heat transfer more difficult
Solution Approach 1:
The patent introduces an intermediary cooling system that uses water evaporation as a mediator between the heat island environment and the condenser. Water is applied to the condenser surfaces and evaporates, absorbing heat and creating a localized cool microclimate around the heat exchanger, thereby improving heat transfer efficiency despite the high ambient temperature
Solution Approach 2:
The patent changes the thermal parameters of the condenser environment by applying water that undergoes phase change from liquid to vapor. This parameter change (temperature and phase) creates evaporative cooling that lowers the effective temperature around the condenser surfaces, improving the temperature differential for heat transfer
2Productivity
If water droplets are dispersed onto the heat rejection heat exchanger, then evaporative cooling enhances heat transfer rates, but the system complexity increases
Solution Approach 1:
The patent implements a self-service water delivery system where the refrigeration unit's own condenser heat rejection process provides the energy needed to evaporate the water. The system uses the existing heat load to drive the evaporative cooling, making the water application system self-regulating and reducing the need for external control mechanisms
Solution Approach 2:
The patent makes the water delivery system multi-functional by using it for both cooling enhancement and potential dehumidification purposes. The same water application mechanism serves multiple thermal management functions, reducing the need for separate systems and justifying the added complexity through versatile utility
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 evaporative cooling increases the temperature difference across the condenser, enhancing heat transfer rates and improving the overall energy efficiency of the refrigeration system.
Implementation Method 1
a water droplet generator in fluid communication with a water tank outlet and configured to disperse water droplets into an air stream flowing to the refrigerant heat rejection heat exchanger
Implementation Method 2
the evaporative cooling increases the temperature difference across the condenser, enhancing heat transfer rates
Implementation Method 3
refrigerant heat rejection heat exchanger... heat transfer from the refrigerant to the surrounding air
Implementation Method 4
a refrigerant compression device... heat from the refrigerant in the condenser
Implementation Method 5
Air or an air/gas mixture is drawn from the interior volume of the cargo space by means of the evaporator fan(s) associated with the evaporator, passed through the airside of the evaporator in heat exchange relationship with refrigerant whereby the refrigerant absorbs heat from the air
Data Source
AI summary
Disclosed is a transportation refrigeration system including a transportation refrigeration unit configured to maintain a temperature in a refrigerated cargo space and comprising a refrigerant expansion device, a refrigerant heat absorption heat exchanger, a refrigerant compression device, and a refrigerant heat rejection heat exchanger; and a refrigeration augmentation unit comprising a water tank having an outlet, and a water droplet generator in fluid communication with a water tank outlet and configured to disperse water droplets into an air stream flowing to the refrigerant heat rejection heat exchanger. Also disclosed are methods of using the transportation refrigeration system.