An Model of Transcritical Co2 Systems Schematic (PDF)
Transcritical CO2 systems are environmental friendly and dependable that defined as a system that operates above the critical point. The transcritical CO2 systems are the most promising solutions that using natural refrigerants in retail contexts. In this system, the heat recovery function exploits the heat normally dissolute by the gas cooler for domestic hot water production or space heating. These systems are suitable for medium to large supermarkets, cold storage facilities and light industrial processes.
Due to low environmental impact of transcritical CO2systems and phasing out CFC, HCFC, and HFC refrigerants, and lower operating cost of transcritical CO2 refrigeration systems. However, increasing demand for refrigeration and air-conditioning applications is anticipated to offer more growth opportunities for the players operating in the transcritical CO2 systems market.
Transcritical CO2 systems are distinguishable by the fact that their working fluids go through subcritical and supercritical states. The fluid (CO2) is first boiled and expanded into a superheated vapor by an evaporator. Then, a compressor is used to increase the heat and pressure of the superheated vapor. Once that pressure exceeds the critical point of CO2 (1055 PSIG/74 BAR), the CO2 is transformed into what’s described as an undefined gas. It has properties of both a liquid and a gas, but is technically neither and is indistinguishable as either state.
Benefits of transcritical CO2 refrigeration:
1. Cost
There are a few notable benefits associated with opting for transcritical CO2. First, when compared to other refrigerants, carbon dioxide is much cheaper on a per-pound basis. For example, R-410A, a popular HFC refrigerant, averages between $6 and $8 per pound. On the other hand, we regularly buy CO2 for less than a dollar a pound.
Changing HFC or HFO systems over to CO2 isn’t practical, and it will take time for the return on investment to be realized, but the cost savings of CO2 compared to traditional refrigerants are real and significant. These cost savings come in the form of cheaper fluids as well as higher attainable efficiency for the system as a whole
2. Sustainability
Unlike synthetic refrigerants like R-134 and R-404A, which have Global Warming Potentials of 1400 and 3260, respectively, CO2’s is negligible with a Global Warming Potential of 1. Because of this, CO2 is often referred to as “future proof,” meaning that as regulatory agencies continue to evaluate and outlaw synthetic refrigerants due to environmental reasons, CO2 will remain a viable option.
3. Heat Reclaim
Because CO2’s index of compression greatly exceeds that of synthetic refrigerants, its discharge temperature (roughly 100 -120°C) is higher than that of traditional HFC refrigerants. Additionally, CO2’s higher enthalpy means more of the rejected heat can be reclaimed, therefore making TC CO2 systems more attractive for heat reclaim purposes. As a general rule of thumb, the higher the system’s ambient temperature, the more heat will be available for reclaim, however CO2 systems still provide usable quantities of recoverable heat even in winter conditions. The reclaimed heat can then be routed to other areas of the operation, such as building HVAC or domestic hot water, improving the system’s efficiency.
Design and material considerations of transcritical CO2 systems:
Given the high pressure of transcritical CO2 systems, more rugged materials are required. At Super Radiator Coils, we design and manufacture three products for TC applications: gas coolers, hot gas reheat coils, and evaporators.
To do so, we rely on tube materials like stainless steel and copper alloy strengthened with nickel and tin along with copper alloy headers and connections. While stainless steel is typically seen more often, copper alloy is an excellent option for TC CO2 applications for a couple reasons. First, it can be brazed, allowing for easy integration into systems with copper connections. It’s also far less costly than stainless steel. The tube material we use is UL listed up to 1740 PSIG (120 bar).
Due to low environmental impact of transcritical CO2systems and phasing out CFC, HCFC, and HFC refrigerants, and lower operating cost of transcritical CO2 refrigeration systems. However, increasing demand for refrigeration and air-conditioning applications is anticipated to offer more growth opportunities for the players operating in the transcritical CO2 systems market.
Benefits of transcritical CO2 refrigeration:
1. Cost
There are a few notable benefits associated with opting for transcritical CO2. First, when compared to other refrigerants, carbon dioxide is much cheaper on a per-pound basis. For example, R-410A, a popular HFC refrigerant, averages between $6 and $8 per pound. On the other hand, we regularly buy CO2 for less than a dollar a pound.
Changing HFC or HFO systems over to CO2 isn’t practical, and it will take time for the return on investment to be realized, but the cost savings of CO2 compared to traditional refrigerants are real and significant. These cost savings come in the form of cheaper fluids as well as higher attainable efficiency for the system as a whole
2. Sustainability
Unlike synthetic refrigerants like R-134 and R-404A, which have Global Warming Potentials of 1400 and 3260, respectively, CO2’s is negligible with a Global Warming Potential of 1. Because of this, CO2 is often referred to as “future proof,” meaning that as regulatory agencies continue to evaluate and outlaw synthetic refrigerants due to environmental reasons, CO2 will remain a viable option.
3. Heat Reclaim
Because CO2’s index of compression greatly exceeds that of synthetic refrigerants, its discharge temperature (roughly 100 -120°C) is higher than that of traditional HFC refrigerants. Additionally, CO2’s higher enthalpy means more of the rejected heat can be reclaimed, therefore making TC CO2 systems more attractive for heat reclaim purposes. As a general rule of thumb, the higher the system’s ambient temperature, the more heat will be available for reclaim, however CO2 systems still provide usable quantities of recoverable heat even in winter conditions. The reclaimed heat can then be routed to other areas of the operation, such as building HVAC or domestic hot water, improving the system’s efficiency.
Design and material considerations of transcritical CO2 systems:
Given the high pressure of transcritical CO2 systems, more rugged materials are required. At Super Radiator Coils, we design and manufacture three products for TC applications: gas coolers, hot gas reheat coils, and evaporators.
To do so, we rely on tube materials like stainless steel and copper alloy strengthened with nickel and tin along with copper alloy headers and connections. While stainless steel is typically seen more often, copper alloy is an excellent option for TC CO2 applications for a couple reasons. First, it can be brazed, allowing for easy integration into systems with copper connections. It’s also far less costly than stainless steel. The tube material we use is UL listed up to 1740 PSIG (120 bar).
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