The natural refrigerant indirect cooling unit “Bacchus” series is an earth-friendly and safe cooling unit that uses ammonia and ethanol. Characteristics of an ammonia and ethanol system As a freezing refrigerant, ammonia had been used a long time ago. After the commercialization of the CFC refrigerants in 1930s, their odorless and low-toxic characteristics led the CFC (R12) and the HCFC (R22) to be widely used in the freezer air-conditioner field. However, the ozone depletion caused by these refrigerants became a global issue, resulting in the 1995 ban on the manufacture of R12. R22 was banned from replenishment for new freezing equipment after 2010. For existing freezing equipment, newly manufactured R22 is to be banned from replenishment after 2020, and the manufacture phase-out plan for R22 has been implemented. Such regulations have been implemented in response to the commercialization of the HFC refrigerants that do not deplete the ozone layer (such as R404A and R134a).

However, these refrigerants also have as high Global Warming Potentials (GWP: an index obtained by comparing the global warming capacity of CO2 defined as 1) as 1430 to 3920; hence, they became subject to the emission restriction for global warming prevention, making it necessary for them to be replaced by a new refrigerant. As for R134a, which is used for air-conditioners, a refrigerant with a GWP as low as 4 (HFO-1234yf) has been developed, and has started to be commercialized in Europe. However, as for R404A and R407C, which are used for freezing, refrigerants with a low GWP are yet under development and give no clear prospects for commercialization, making it difficult to take action on the issue. Should we wait for the commercialization of a low-GWP refrigerant while using HFCs, or should we go back to natural refrigerants such as ammonia...? Now, refrigerants are at a turning point. Under such a situation for freezing refrigerants, NISSIN has been examining countermeasures from aspects of both CFC refrigerants and natural refrigerants in an attempt to flexibly cope with the issue.

Ammonia is the most popular natural refrigerant. Ammonia refrigerants do not deplete the ozone layer or have any global warming effect. However, they have a strong odor, are toxic, and slightly flammable, requiring safety consideration. The following shows a comparison of the characteristics of ammonia refrigerant systems. Indirect cooling system by CO2 refrigerant Indirect cooling system by standard brine Since CO2 cannot be heated to -5°C or higher, one of the following operations needs to be performed. 1. Install an expansion tank (with a capacity of 150 times as much as the liquefied CO2) into the system. 2. Operate the NH3 freezer when the CO2 pressure in the system increases. 3. Install a small freezer for maintaining temperature. 4. Release CO2 to the atmosphere when the system is stopped for a long period of time. NISSIN’s natural refrigerant cooling system “Bacchus” ensures safety and maintainability by using “ethanol brine “ as a medium for cooling the refrigerator.

Bacchus has other features than brine. According to the International Chemical Safety Card, the flash point of 59% ethanol is 22°C (concentration in the air: 3.3%). - 22°C or lower: No risk of ignition. - 22°C or higher: Ignition does not occur if the concentration in the air is 3.3% or lower. ⇒ This can be coped with by ventilation.Descriptions on the International Chemical Safety Card for CO2electric furnace and ac units Although the permissible concentration is 5000 ppm,ac unit drainage As for “physical hazard,” it is heavier than the air, and in a place where the ceiling is low, it may cause oxygen deficiency.hvac split system vs. packaged unit As for “inhalation hazard,” if the container is opened, the liquid evaporates very rapidly.

In a closed room, it pushes the air out of the room, potentially causing the risk of suffocation. ⇒ In the case of CO2, the boiling point under atmospheric pressure is as significantly low as -79°C. Hence, an entire leak will be gas. Since CO2 gas is heavier than the air, it builds up at the bottom of a room.How do you keep millions of pounds of fresh produce from not baking in the furnace that is California’s Central Valley during peak production in the summer? With aircraft-carrier-length refrigerator-warehouses, which can never fail — that is, without round-the-clock upkeep and repairs from specialized field techs who must be expert at everything from basic parts replacement to the safe handling of hazardous chemicals. Here’s a look at how field techs at one leading industrial refrigeration servicer keeps the produce fresh — and their cool when the pressure rises. It’s not just any refrigerator, but an industrial refrigeration unit that’s roughly the size of three-and-half football fields. 

CaliforniaControlled Atmosphere (CalCA) is the Central Valley leader in industrial refrigeration units. Its team of 24/7 field service technicians offers a full-stop shop for the development, installation, maintenance and repair of industrial refrigeration units. What started out in a garage on a five-acre raisin farm in 1984 is now an employee-owned corporation servicing some of the world’s largest commercial farms. “A typical home might have a three- to five-ton air conditioning unit to cool the house,” explains Jay Kliewer, the company CEO and son of founder Ray Kliewer, “An industrial refrigeration unit, however, can weigh 100 to several thousand tons and range in size from 10,000 to 200,000 square feet.” Unlike the average household AC unit, industrial refrigeration machinery doesn’t come pre-packaged. They are made up of many moving parts with each individual component designed to carry out a specific operation. Most emergency calls to CalCA come when these multimillion-dollar units reach temperatures higher than 50 degrees maximum, with 32 degrees being the standard for most produce storage.

“If we get a call that the system isn’t performing,” says Kliewer, “the reason can be anything from a switch malfunction, a motor going out or simply that a door was left open — and everything else in-between.” For the agriculture industry, a broken refrigeration unit is a ticking time bomb. Some products have more forgiving shelf lives than others, like citrus, but for others, like table grapes, farmers have to scurry to get the product onto grocery store shelves fast. “Depending on the problem, things can get pretty urgent,” says Kliewer, adding that the company offers a 24-hour emergency number and always has a field tech on call. One major CalCA customer is a table grape farm that posts annual sales of about $100 million, or more than $9 million a month. This summer alone, CalCA techs have been called in six times to repair leaks in the refrigeration unit’s ammonia-filled cooling coils. Rather than use freon, the most common cooling agent used as a refrigerant, CalCA uses ammonia – a natural refrigerant that is more environmentally friendly.

Unlike most refrigeration units, the ones for storing grapes are more vulnerable to leaks because of the corrosive effects of the fumigants used. “The first telltale sign of an ammonia leak is the smell in the air,” says Kliewer. “If the leak isn’t fixed soon, ammonia can leak from the coils damaging millions of dollars worth of grapes.” In these crisis situations, a team of three CalCA service techs will race to the farm. One handles pumping the ammonia out of the compromised section of cooling coils and the other two weld aluminum to repair the leak. The trio can usually get the refrigeration unit up and running within 24 hours, according to Kliewer. “Our service techs often are under pressure to fix a problem within half a day to a day’s time,” says Kliewer. But identifying the problem is only the first step; the next hurdle is getting the right replacement parts. While the service techs have on hand many of the most common parts, such as valves and switches, sometimes there is a need for a specialized part, like a 300-horsepower motor that powers refrigerators and requires about a day for delivery.