Energy efficiency is the value obtained by dividing the energy obtained by the energy used to obtain this energy. It is a simple phrase to put in one and get more than one. The higher the multiple, the greater the energy efficiency of the system. This logic is used in the calculation of the energy efficiency of air conditioning, cooling and heating appliances. Some concepts are used to determine energy efficiency in cooling and heating applications. In describing these concepts, instantaneous and seasonal work of unit difference system was considered.
Performance Coefficient (COP)
Performance coefficient; is the ratio of the output energy to the input energy. It is normally used to measure the heating efficiency in the heat pump or in the cooler. COP value in heat pumps used for heating can be calculated by the following formula.
COP (Heating Efficiency Coefficient) = Condenser Heating Capacity (kW) / Total Energy Expended (kW)
Energy Efficiency Ratio (EER)
The Energy Efficiency Ratio (EER) is the ratio of the cooling capacity (kW) achieved in the evaporator to the total electrical energy (kW) consumed by the appliance in a refrigerator. The EER value is used for cooling purposes only. Then equality can be written as
EER (Energy Efficiency Ratio) = Evaporator Cooling Capacity (kW) / Total Energy Expended (kW)
Calculation of EER Value
Classification of energy consumption of heating and cooling devices is determined by COP and EER values. In the Standards section, a lot of information is given about them. These values are the result of test and measurements made under certain conditions. If the working conditions in practice are continuously variable, COP and EER are constantly changing in the values.Therefore, these values are instantaneous values. In order to calculate the EER in practice, the following measurements must be made. The expansion valve must measure the inlet temperature (liquid fluid), the evaporator outlet temperature (fluid saturated steam or hot steam), the fluid flow (fluid line before the expansion valve), and the total energy the system has consumed ( compressor , condenser fan, evaporator fan, etc.). It should be noted that measuring instruments comply with calibrated standards.
Example 1:
According to the measurement results below, we have the EER value of the air-cooled split air conditioner working with the R-22.
• TXV or capillary inlet temperature = 40 ° C
• Evaporator outlet temperature = 10 ° C
• Fluid flux = 0.07 kg / s
• Total power drawn by the device = 3.8 kW
Solution 1:
TXV or capillary inlet temperature = 40 ° C liquid (R-22 saturated steam table, h1 = 249,6 kJ / kg)
Evaporator outlet temperature = 10 ° C steam (R-22 saturated steam table, h2 = 408,6 kJ / kg)
EER = Q ev / Q totlam = m. (H2-h1) / Qt = 0,07. (408,6-249,6) / 3,8 = 11,13 / 3,8 = 2,92
Example 2:
In a beer cooling system ethylene glycol is used as the secondary fluid. The following values were obtained in the measurements made. Calculate the EER of the device.
Measured values:
• Ethylene glycol evaporator inlet temperature = – 1 ° C
• Ethylene glycol evaporator outlet temperature = – 4.5 ° C
• Ethylene glycol ratio = 3,5 kg / s
• Total energy consumption = 40 kW
• Specific heat of ethylene glycol = 9.78 kJ / kg ° C
EER = Qevap / Qtoplam = m. c. (T2-T1) / Qt = 3,5 * 9,78 * (-1 – (-4,5)) / 40 = 119,8 / 40 = 2,99
Calculation of Chillers’ Partial Overhead Yield
Expresses the seasonal or annual productivity of chillers for cooling purposes. The ratio of the cooling capacity (kW) you have achieved during a season to the total electrical energy (kW) consumed by the refrigeration devices at the same time. Different units are used in this ratio.Efficiency calculations for cooling systems should be calculated not only at full load but also at partial loads. In particular, the chiller runs at 100% full load for a very short time. For this purpose, the average ESEER or IPLV values are tried to be calculated according to the performance values of chillers at 75%, 50% and 25% capacities. Values a, b, c and d in the table indicate the loading rates (working capacity) in% of the chiller. a = indicates EER value at 100% capacity, b = EER value at 75% capacity, c = EER value at 50% capacity, and d = EER at 25% capacity.ESEER value is formulated according to European working conditions and IPLV is formulated according to US working conditions. The coefficients given in the formulas represent the seasonal or annual average percentage of the operation according to the condenser air and water inlet temperatures in that region. For example, in Europe (ESEER), the condenser accepts air cooled chillers with an air inlet temperature of 35 ° C, or 3% of the total operating time per year at 100% (a) capacity. But this value is taken as 1% for America (IPLV) conditions. Likewise, in Europe (ESEER), it assumes that the water-cooled chiller with a condenser water inlet temperature of 22 ° C is capable of 41% of the total operating time per year, or 50% of the total operating time. In the US, the condenser water inlet temperature is 45% at 18.3 ° C. These values are seen to change regionally. Since ESEER or IPVL values indicate the efficiency of the devices at partial loads, it is an important value when comparing the devices in terms of efficiency during purchase.
According to Eurovent standards, ESEER (European Seasonal Energy Efficiency Ratio);(European Seasonal Energy Efficiency Rate). Table 2.4 gives partial load ratios of chillers according to Eurovent standards. According to European Eurovent standards, ESEER value is calculated according to the following formula.
ESEER = 0.03xEERa + 0.33xEERb + 0.41xEERc + 0.23xEERd
Table 2.4 Chiller partial load ratios according to Eurovent standards
| Symbol | Loading rate, capacity (%) | Air-cooled chiller Condensate air inlet temperature (° C) | Water cooled chiller Condensate water inlet temperature (° C) |
| a | one hundred | 35 | 30 |
| b | 75 | 30 | 26 |
| c | 50 | 25 | 22 |
| D | 25 | 20 | 18 |
According to AHRI standards, IPLV (Integrated Part Load Value); It can be expressed as Integrated Partial Load Value. Table 2.5 gives partial load ratios of chillers according to AHRI standards. According to the AHRI standards, the IPLV value is calculated by the following formula.
IPLV = 0,01xEERa + 0,42xEERb + 0,45xEERc + 0,12xEERd
Table 2.5 Chiller partial load ratios according to AHRI standards
| Symbol | Loading rate, capacity (%) | Air-cooled chiller Condensate air inlet temperature (° C) | Water cooled chiller Condensate water inlet temperature (° C) |
| a | one hundred | 35 | 29.4 |
| b | 75 | 26.7 | 23.9 |
| c | 50 | 18.3 | 18.3 |
| D | 25 | 12.8 | 18.3 |
Seasonal Heating Performance Factor (HSPF)
It is often a term used to determine the heating efficiency of heat pumps . The energy rate of the heat pump’s BTU seasonal heating value (BTU / Wh).
Annual or Seasonal Energy Efficiency (AFUE)
AFUE is a concept used to determine annual or seasonal energy efficiency of heating appliances such as boilers and boilers. Annual or seasonal fuel use efficiency refers to annual or seasonal fuel efficiency of heating appliances. It shows how much of the fuel used in heating devices, whether annual or seasonal, is converted to heating energy and expressed as a percentage.Annual or seasonal fuel use efficiency does not take into account the electricity consumption of fans, pumps and control elements used in boilers and boilers. As a measure only the efficiency of the fuel is taken into account.
Source: Friterm