NOM-012-ENER Energy Efficiency of Condensing and Evaporating Units for Refrigeration - Limits, Test Methods and Labeling

Since the use of condensing and evaporation units used in rooms, cabins or cooling processes requiring energy from the electrical network has increased rapidly in recent years, it was considered necessary to develop a standard to determine the energy efficiency of these equipment, to control their cooling capacities and to contribute to the protection of non-renewable natural resources by reducing the energy consumption of this concept by integrating these units into a cooling system.

The standard “NOM-012-ENER Energy efficiency of condensing and evaporating units for refrigeration - Limits, test methods and labeling”, published under the Official Mexican Standard (NOM), describes the energy efficiency requirements that condensing and evaporating units must meet, as well as test methods to verify compliance, labeling and the procedure for evaluating the conformity of products.

The scope of this standard includes:

• Condensing units for cooling purposes manufactured for outdoor or indoor installation. Indoor spaces with a cooling capacity of 746 W or more and 26.000 W or less at medium temperature and 9.500 W or less at low temperature.
• Low profile evaporator units for refrigeration purposes, designed for operation with a direct expansion feed and a chiller in humid or dry conditions, having nominal cooling capacities of 300 W or greater and 40.000 W or less at medium temperature and 13.000 W or less at low temperature.

The following are outside the scope of this standard:

• Comfort air conditioning units (environments where the air temperature is above 15,0 degrees and must be evaluated according to the applicable air conditioning energy efficiency standards).
• Cooling air distributors or evaporators (air handlers) mounted in or connected to ducts.
• Tandem (rack type) cooling systems where more than one compressor is operated in parallel.
• Condensing units with frequency converters, called inverter type due to their characteristics and technical features offered (this exception must be authorized by the organization that published this standard).
• Equipment specifically designed to operate with the natural refrigerants ammonia and carbon dioxide.

Condensing and evaporation units are classified differently based on their cooling applications and usage in cooling systems:

• Classification of condensing units: Air-cooled condensing units with fixed or variable gross cooling capacity covered by this standard are classified according to their cooling applications and usage or installation as follows:
  • According to cooling application:
    • Medium temperature: Any cooling application operating at air temperatures between 0,0 degrees and 15,0 degrees
    • Low temperature: any cooling application operating at temperatures between minus 40,0 degrees and 0,0 degrees
  • According to usage and installation method:
    • Indoor use
    • Outdoor use
  • According to their capacities:
    • Fixed capacity
    • Variable capacity
    • Fixed capacity with variable capacity motor
  • By cooling type:
    • water cooled
    • air cooled
• Classification of evaporator units: Evaporator units within the scope of this standard are classified according to their type, size and design, taking into account their nominal cooling capacity, as follows:
  • By type of air circulation:
    • By forced convection (fans)
  • According to coolant supply:
    • Direct expansion (dry expansion)
  • By type of defrosting:
    • Electrics
    • By air
    • With gas (hot or cold)
  • According to the type of structure:
    • Finned

Condensing units within the scope of this standard must comply with the gross cooling capacities specified in the table entitled “Minimum standardized energy efficiency factor level to be met according to the power of the condensing unit ” and with the standardized energy efficiency factor values ​​in accordance with the test method described in this standard.

Likewise, the cooling capacity and electrical power consumption values ​​of these units must comply with the values ​​declared by the manufacturer with a tolerance of plus/minus 5,0 percent compared to the value stated on the label.

Evaporator units within the scope of this standard must comply with the cooling capacities specified in the table titled “Minimum level of standardized energy efficiency factor on evaporator units for cooling” and the standardized energy efficiency factor values ​​in accordance with the test method described in this standard.

Likewise, the cooling capacity and electrical power consumption values ​​of these units must comply with the values ​​declared by the manufacturer with a tolerance of plus/minus 5,0 percent compared to the value stated on the label.

To determine the cooling capacity and standardized energy efficiency factor of equipment covered by this standard, the following tests must be performed:

• Steady-state performance tests of the tested condensing units. The steady-state performance test should take into account the test conditions specified in the table given in the standard, the refrigerant inlet and outlet parameters should be determined under these conditions, and temperature and pressure measurements should be made according to the test method to determine the gross cooling capacity under these conditions.
• Evaporator unit steady state performance tests. The steady state performance test shall take into account the test conditions specified in the table, where the humidity and temperature conditions of the air inlet to the evaporator unit are determined, a condensing temperature of 40,5 degrees, a constant refrigerant superheat of 5 degrees (5K) and a subcooling of 1 degree (1K) are provided, and under these conditions, temperature and pressure measurements are carried out according to the test method in question to determine the gross cooling capacity.

The tables given in the standard specify the standard evaluation conditions under which the steady state performance tests of the condensing and evaporating units, respectively, should be performed.

The condensing units being tested should be connected to a calorimeter capable of providing and controlling the gross cooling capacity stated on the manufacturer's label. An evaporator meeting the steady-state conditions given in the table may be used for testing.

To measure the refrigerant mass flow rate, a liquid flow mass flow meter is installed at the outlet of the condensing unit. It should be ensured that there is a single-phase refrigerant flow from the liquid cooling mass flow meter.

Our organization, which has been trying to support businesses from every sector with its wide range of testing, measurement, analysis and evaluation studies for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services are also provided to businesses in accordance with the standard “NOM-012-ENER Energy efficiency of condenser and evaporator units for cooling - Limits, test methods and labeling”.