NISSIN has been making contributions with the leading-edge technologies to a wide range of industries, including shipping, ice making and refrigerating warehouse, building air-conditioners, and special air-conditioners.

What is Cascade refrigeration system?

　The cascade refrigeration system is a freezing system that uses two kinds of refrigerants having different boiling points, which run through their own independent freezing cycle and are joined by a heat exchanger. The schematic view and the P-h diagram of this system are shown below.

　This system is employed to obtain temperatures of -40 to -80°C or ultra-low temperatures lower than them.
　At such ultra-low temperatures, a common single-refrigerant two-stage compression system limits the low-temperature characteristics of the refrigerant to a considerably poor level, making the system significantly inefficient. The efficiency is improved by combining two kinds of refrigerants having different temperature characteristics.

　This system has the following advantages compared to a two-stage compression system:

• 1. Energy is saved because the system allows use of refrigerants that have suitable temperature characteristics for each of the higher-temperature side and the lower-temperature side.
• 2. It allows stable ultra-low-temperature operation.
• 3. The running cost is inexpensive.
• 4. Repair is easy.

　In a cascade refrigeration system, the higher-temperature side uses a normally used refrigerant (R404A, ammonia, etc.), and the lower-temperature side uses R23, which is an HFC refrigerant.

"Kuroshio", a new eco-friendly cascade refrigerator

1. Global warming of refrigerant has been an issue worldwide.

(Japan) Fluorocarbons Emission Control Law was enacted in 2015.

Although not eligible for the ultra low temperature devices,
refrigeration system should have a GWP value of less than 1500 by 2025.

(Overseas)  - Under Paris Agreement, Co2 emission in Japan should be reduced by 26%
　　　　　　　　　between 2020 and 2030.

- Under MOP 28, industrialized countries should reduce GWP converted
  HFC refrigerant production by 85% from 2019 to the end of 2035.

  

2. Up to the present, R404A and R23 of the Cascade refrigeration system has been the
        mainstream of the ultra-low temperature.
　　　 However, they have large GWP values; 3920 for R404A and 14800 for R23.

Recently, ultra low temperature devices using air refrigerant are released, but with low energy efficiency and high power consumption. In addition, being a specific device, it requires high initial and maintenance costs.

3. Therefore, we have developed an ultra low temperature cascade refrigeration system using
        refrigerant with less GWP values.

The appearance of Eco-friendly "Kuroshio"

　　　 The refrigerant of "Kuroshio" used are R32 (GWP=675) and R407E (GWP=1550).
　　　 This reduces GWP of the system by 88%.

　　　 Note that R407E can be replaced in almost a day, even when the new refrigerant
　　　 (R454A, GWP=239) appears, that are expected to be released in the future.

　　　 The features of "Kuroshio", an evolutionary cascade refrigerator are as follows: