Refrigeration device for land transportation
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Solution Overview
Problem
The sub-engine in multi-evaporator-type land-transport refrigeration systems cannot be stopped efficiently due to irregular thermostat on-off timings, leading to high fuel consumption, as the thermostat cannot be turned off for all evaporator units simultaneously.
Innovation Solution
Implementing a thermostat-off retaining operation mode that delays the refrigeration cell from reaching the operation-regaining temperature until all cells are in a thermostat-off state, allowing the compressor and engine to be stopped, thereby reducing fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thermostat is turned on and off for each evaporator unit at irregular timings in a multi-evaporator-type refrigeration system, then temperature control for multiple cells is achieved, but the sub-engine cannot be stopped efficiently leading to high fuel consumption
Solution Approach 1:
The system performs preliminary cooling to achieve a predetermined temperature difference (ΔT) below the set temperature before stopping the engine. This advance action ensures that even when the engine stops and cooling ceases, the temperature will not rise above the acceptable range during the stop period, enabling effective engine shutdown to reduce fuel consumption.
Solution Approach 2:
The invention dynamically adjusts the control strategy based on real-time temperature conditions. When the temperature difference between the actual temperature and set temperature reaches the predetermined ΔT, the system transitions from continuous cooling to intermittent cooling with engine stoppages. This dynamic adjustment optimizes the balance between temperature control accuracy and fuel consumption.
2Temperature
If the sub-engine operates continuously to maintain temperature accuracy, then temperature control is improved, but fuel consumption increases
Solution Approach 1:
The system implements periodic engine operation instead of continuous operation. The engine runs periodically to maintain the temperature difference within the predetermined range, and stops when the lower threshold is reached. This periodic action pattern reduces overall fuel consumption while maintaining acceptable temperature accuracy through the buffer of the predetermined temperature difference.
3Use of energy by moving object
If the thermostat is turned off for one evaporator unit, then fuel consumption is reduced for that unit, but other units may require cooling so the engine cannot stop
Solution Approach 1:
The invention merges the control of multiple evaporator units into a unified control strategy. Instead of independently controlling each evaporator, the system evaluates the aggregate temperature conditions of all cells and makes engine stop/start decisions based on the overall system state. This allows the engine to stop when all units are sufficiently cooled, enabling fuel savings while maintaining control over all cells.
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 approach reduces fuel consumption by ensuring all refrigeration cells are in a thermostat-off state, eliminating the need for continuous engine operation and enhancing temperature accuracy by managing temperature differences.
Implementation Method 1
a compressor (5) that compresses the refrigerant
Implementation Method 2
a condenser (9) that releases heat from the refrigerant compressed by the compressor (5) to the surrounding environment
Implementation Method 3
an evaporator (13) that absorbs heat from the refrigeration cell (3) by evaporating a refrigerant
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Provided is a land-transport refrigeration system that can maintain a reduced fuel consumption effect even when operating under a multi-evaporator-type automatic start-stop operation mode. The system includes a compressor (5) driven by an engine (7); a plurality of evaporator units disposed respectively in cargo compartments (3A, 3B, and 3C) and parallel-connected to a refrigerant circuit (17) through which a refrigerant circulates; and a controller (15) having an automatic start-stop operation mode (27) that stops the operation of the compressor (5) or the evaporator units when set temperatures are reached and that resumes the operation of the compressor (5) or the evaporator units when operation-regaining temperatures set to be higher than or lower than the set temperatures by a predetermined temperature are reached. The automatic start-stop operation mode (27) includes a thermostat-off-condition retaining operation that prevents the temperature in the cargo compartment having reached the corresponding set temperature from reaching the corresponding operation-regaining temperature until all the cargo compartments (3A, 3B, and 3C) reach their respectively set temperatures.