Refrigeration Control via Eutectic Plates and Compressor Speed
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Solution Overview
Problem
Refrigerated truck systems face challenges in maintaining accurate temperature control during transportation, especially when the engine is not running, leading to excessive temperature variations due to the inability to operate the evaporator when solar power is low or the truck is stopped.
Innovation Solution
A system that includes a mode module to determine whether to operate in engine mode or battery mode based on parameters, adjusting the compressor speed and refrigerant flow through eutectic plates to maintain temperature control, with the engine module running the compressor at a first speed and charging the battery when the engine is on, and the battery module running the compressor at a second speed and preventing refrigerant flow when the engine is off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the evaporator is operated when the truck is stopped or solar panel output is low, then temperature control within the box is maintained, but power consumption increases and battery is depleted
Solution Approach 1:
The system pre-cools the eutectic plates during periods when the engine is running or solar power is available, storing cooling capacity in advance. This preliminary action allows the evaporator to be turned off during stops or low-power periods, maintaining temperature control without additional power consumption.
Solution Approach 2:
The eutectic plates serve as an intermediary thermal storage medium between the compressor and the box contents. They absorb and release thermal energy, mediating the temperature control function and allowing the evaporator to operate intermittently rather than continuously.
2Use of energy by moving object
If the evaporator is turned off to conserve battery power, then power consumption is reduced, but temperature variation within the box increases
Solution Approach 1:
The system pre-charges the eutectic plates with cooling capacity before the evaporator needs to be turned off. This ensures that when the evaporator is off, the pre-charged eutectic plates continue to provide cooling, preventing temperature variation while conserving battery power.
Solution Approach 2:
The system changes the operational parameters by switching between active evaporator cooling and passive eutectic plate cooling based on power availability. This parameter change allows the system to maintain temperature control through different mechanisms depending on whether the engine is running or the truck is stopped.
3Temperature
If refrigerant is continuously flowed through eutectic plates, then cooling capacity is maintained, but energy is wasted when not needed
Solution Approach 1:
The system implements periodic action by cycling refrigerant flow through the eutectic plates only when needed for charging or cooling, rather than continuous flow. The control system activates refrigerant flow during engine operation to charge the eutectic plates and during cooling demands, preventing energy waste during periods when cooling capacity is already sufficient.
Solution Approach 2:
The control system uses feedback from temperature sensors and engine status to regulate refrigerant flow through the eutectic plates. When the engine is running and the eutectic plates are adequately charged, or when box temperature is within acceptable ranges, the system reduces or stops refrigerant flow to prevent energy waste.
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 solution ensures accurate temperature maintenance within the truck, reducing power consumption and battery drain, and minimizing the need for engine operation, thereby improving the transportation of both frozen and perishable goods.
Implementation Method 1
A compressor may be used in a wide variety of industrial and residential applications to circulate refrigerant
Implementation Method 2
The eutectic plates are filled with a fluid and are designed to freeze at a certain temperature
Implementation Method 3
a blower/evaporator (hereinafter referred to as an 'evaporator'). The evaporator is run as needed and to maintain a temperature within a box of the truck
Data Source
AI summary
A system including mode, engine, and battery modules, where the mode module determines whether to operate in an engine mode or a battery mode based on parameters. The engine module, while operating in the engine mode, runs a compressor at a first speed based on a temperature within a temperature controlled container of a vehicle and permits passage of refrigerant through eutectic plates independent of the temperature. A battery, while in the engine mode, is charged based on power received from an electrical source. The battery module, while operating in the battery mode and based on the temperature, runs the compressor at a second speed and prevents passage of the refrigerant through the eutectic plates. While in the battery mode, the battery is not being charged based on power from a shore power source and the electrical source from which power is received during the engine mode.