Liquid Nitrogen Mixer Cooling for Crack-Free Fresh Concrete
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Solution Overview
Problem
Existing methods for cooling fresh concrete at elevated temperatures are inefficient, costly, and environmentally harmful, failing to maintain optimal temperature and leading to cracks and fissures due to rapid water evaporation and plastic shrinkage.
Innovation Solution
A device using liquid nitrogen injection directly into the concrete mixer, controlled by a PLC system, to cool fresh concrete to the desired temperature without affecting consistency or workability, with reduced nitrogen consumption and simplified maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid nitrogen is injected into the concrete mixer to cool fresh concrete, then the cooling efficiency and temperature control are improved, but the device complexity increases
Solution Approach 1:
The cooling device is divided into modular components: a cooling station with solenoid valves, a collector with nozzles, temperature probes, and a PLC control system. This segmentation allows for easier installation, maintenance, and controlled nitrogen consumption while achieving efficient cooling of fresh concrete by up to 15°C.
Solution Approach 2:
The device incorporates temperature probes that provide real-time feedback to the PLC control system, which automatically regulates the solenoid valves to control liquid nitrogen injection. This feedback mechanism ensures precise temperature control without requiring complex manual intervention, resolving the contradiction between cooling efficiency and device complexity.
2Temperature
If traditional cooling methods are used, then the equipment space is reduced, but the cooling efficiency and temperature control capability are insufficient
Solution Approach 1:
The device uses liquid nitrogen in its liquid phase for cooling, which undergoes phase change to gas upon contact with warm concrete. This parameter change (liquid to gas) provides highly efficient cooling with compact equipment volume, as the phase change occurs directly within the mixer, eliminating the need for large external cooling chambers or tanks.
3Temperature
If more liquid nitrogen is consumed to achieve better cooling, then the temperature control is improved, but the nitrogen consumption and costs increase
Solution Approach 1:
The device dynamically adjusts liquid nitrogen consumption based on real-time temperature feedback from probes. The PLC system modulates solenoid valve opening times and positions, allowing precise control of nitrogen injection rates. This dynamic adjustment optimizes cooling efficiency while minimizing nitrogen consumption, achieving up to 15°C cooling with controlled substance loss.
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
Achieves efficient cooling of fresh concrete by up to 15°C, reducing capital investment, equipment space, and costs, while preventing cracks and fissures, and enhancing consistency and setting time.
Implementation Method 1
liquid nitrogen injected into the concrete mixer during the concrete mixing process... liquid nitrogen for cooling fresh concrete achieved without negative effects
Implementation Method 2
liquid nitrogen injected into the concrete mixer... evaporates and thus cools it to a given temperature
Data Source
AI summary
The device and procedure for cooling fresh concrete at elevated temperatures enable efficient cooling of fresh concrete, which is achieved by the subject device comprising of: cooling station (1) with measuring and regulating equipment (2) and safety equipment (3), solenoid valves (5), pressure transmitter (6), cryogenic shut-off valves (7), collector (17) made of stainless steel pipes with temperature probes (8), concrete mixer (9) and manometer (10) with safety valves (11).The procedure of cooling fresh concrete using liquid nitrogen in the mixer is carried out as follows: first aggregate-separated gravel is added, then cement, then water and finally, if necessary, additives-chemical additives. Mixing of added raw materials lasts from 15-20 seconds, until a homogeneous mixture is obtained, after which liquid nitrogen is added at a pressure of 6 bar, giving cooled fresh concrete on which no surface cracks and fissures appear at external temperatures of 30-35° C.