Our Mission: supporting the global effort of reducing greenhouse gas emissions by working with organizations to save energy, reduce their carbon footprint and increase profitability.

The following information outlines some of the basic strategies we have adopted with our TCI Refrigeration Control System. If you have any comments or questions, please click to contact us. We appreciate all feedback.

Dynamic Suction Control

• Too low a suction pressure wastes energy and may affect quality; both cost money
• Can be based on the product temperature required instead of a straight fixed pressure.
• Each psi (7 KPa) increase = 2% savings.
  
  
• TechCold Solutions
  • Allow dynamic reset of the suction pressure to accommodate the present product requirements.
  • Allow dynamic reset of the suction pressure to accommodate the present utility rates.

Dynamic Suction Control

• The Core Temperature Initiative (due February, 2009)
  • Allow dynamic reset of the suction pressure based upon the ideal product core temperature
  • Variables such as products depth, belt speed, temperature gradients, etc are utilized to determine product core temperatures.
    

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Compressor Dynamic Selection Control

• Compressors are inefficient at low slide valve settings. TCI will choose which compressors to load, load these machines to 100% and select the best trim machine(s) to satisfy load demand, maximize efficiency and compressor output.
• Dynamic Selection Control is performed in real time. Variables such as capacities and COP are taken into consideration as TCI selects the desired mix of compressors.
  

It is important to operate the compressors as close to a 100% slide valve setting as possible

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Compressor Variable Speed Modulation Control

• Capacity and power changes have an almost directly proportional relationship with the variance in the compressor speed (above 50% of maximum speed).
• For this reason, when a variable speed device is available, it is prudent to operate it as the trimming machine as much as is possible.
• TCI will accommodate this by determining which compressors (based on capacity) should be turned on and off in order to attempt to keep the variable speed compressor within its 50% to 100% range.
• When the variable speed compressor cannot be kept within range TCI will operate all units in accordance with the standard slide valve controller algorithms.
  

Compressor Modulation Control

• Part load ratios will determine the settings of the two modulating compressors. (UofW graph)
• All others will be set at 100% loading.
  

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Source: Manske, K., “Performance Optimization of Industrial Refrigeration Systems”,
MS Thesis, University of Wisconsin-Madison, (1999)

Compressor Dynamic Selection Control

• The TechCold Solution:
  • The TCI creates and models all possible sets of compressors.
  • When in a period of low volatility, the existing compressor set can be replaced with one of higher efficiency.
    

Evaporator Control

• Discharge Pressure Reset during hot gas defrost in order to allow reduced head pressure at other times.
• Zoned control through separate temperature indication will allow “load shifting”.
• Anti-stratification fan control instead of continuous operation.

Dynamic Discharge Pressure Control

• Must be high enough for proper process control.
  • Insure proper liquid flow through the system.
  • Provide proper hot gas defrosting.
  • Provide adequate liquid for liquid cooled compressors.
  • Pressure must be above the ambient wet bulb temperature or there will be higher condenser energy waste.
    

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Source: Manske, K. A., Reindl, D.T., and Klein, S.A., “Evaporative Condenser Control in Industrial Refrigeration Systems”,
International Journal of Refrigeration, Vol. 24, No. 7, pp. 676-691, (2001)

Must be as low as effectively possible

• Reduces Power Requirements (Rule of Thumb: 2 psi (14 KPa) = 1% savings)
• Increases Refrigeration Capacity

The TechCold Solution:

• The TCI will float the discharge pressure based upon the ambient conditions and the capabilities of the system.
• The TCI plans include the indication of abnormalities in the operation of the condenser system such that maintenance will restore proper operation and gain maximum savings.
  

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