1. Improve efficiency of cooling systems

2. Step by step Audit Map cooling system
Identify energy consumption of cooling system
Evaluation of existing cooling system
Verify cooling load
Identify saving measures

3. Energy schema
Energy schema of a 2.2 kW freeze facility

4. Map cooling system I

5. Map cooling system II

6. Manufacturers data Cooling capacity (kW) Vaporizer capacity (kW)
Electrical input power (kW)
Condenser power (kW)
Performance (COP)
Mass flow (kg/h)
Volume flow of oil cooler, power (m3/h, °C, kW)
Operation limits (condensation temperatures max, min), evaporating temperatures (°C)

7. Additional components

8. Temperature levels

9. Additional data to measure

10. Evaporation and condensation charts
Evaporation and condensation charts of individual cooling liquids help to identify evaporation and condensation temperatures at given pressure
Most pressure manometer measure gauge pressure in relation to ambient pressure – both pressure levels need to be added to achieve absolute presure
On site measurements to be conducted by using Schrader valves
Evaporation and condensation charts to be obtained from technology/coolpack.aspx

11. Calculating the energy consumption
Assumption: A cooling plant operates at 60%.
ECcooling system = (Pcomp *0.6 + Pp,c,o * 0.9+ PL,c,o * 0.9) * BZ
Alternatively it is possible to calculate the full load operating time (part time operations will be calculated in full load operating times, e.g. 2 hrs part load gives one hour full load)
ECcooling system = Pcomp*FLH + Pp,c,o*FLHp + PL,c,o * FLH l,c,o
A cooling plant operates at 60%. This is an average value and can strongly vary for a concrete plant (+/-50%)
ECcooling system = Energy consumption
FLH = Full load hours

12. Full load operating times

13. Calculating energy consumption with cooling load
Energy consumption compressor = Qo (Cooling load) / Coefficient of Performance * Running Time

14. Outdoor temperature variation in Austria over one year
Frequency scale
temperature

15. Calculating energy consumption with load profile

16. Energy consumption with measurements

17. Example measured energy consumption hotel
2 compressors
Deep cooling: compressor 16kW, R404A, -38°C (7,047 h FLO); on/off
General cooling: compressor 25kW, R134a, -10°C (4,274 h FLO) (piston bypass)
Direct evaporation, pumps: 4kW; fans: 16kW (1,964 FLO); on/off
Electricity consumption cooling area includes: Lighting, fans, electrical deicing, heating windows, door heating, heating condensate

18. Break down electricity consumption

19. Coefficient of Performance
Q = the heat supplied to or removed from the reservoir
P is the work consumped by the compressor

20. Losses

21. Cooling rooms – area of losses

22. Operating figures

23. Energy saving opportunities I
Switch off cooling chamers not in use
Check if cooling temperatures can be adjusted (increased):
Storage temperature recommendations
Check factors which request max. temperatures
Check storage procedures:
Cooling chain must not be interrupted
Seal pass between lorry and cooling chamber
Avoid to intermediate store in warm rooms

24. Energy saving opportunities II
Check for opportunities to use waste heat
Free cooling: freshly cooked products not directly in storage rooms; pre-cool with ambient air (check hygiene standards

25. Energy saving opportunities III
Reduce heat input through doors
Staff training: close doors
Alarm after predefined periods
Check, clean and exchange door seals
Automatic door closing device (€ 120)
Install plastic curtains

26. Insulation
Recommended U-values and insulation thickness for storage rooms for general cooling / deep cooling: 80mm and 170mm PUR
Continuous termal imaging to identify losses and thermal bridges
Avoid cable ducts / ventilation ducts leading through cold rooms

27. Reduce waste heat caused by illumination
LEDs (E27) can replace incandescent lamps used in deep cooling chambers
Ballasts to be installed outside the cooling chamber
Adjust illumination power to real needs
Adjust illumination times (movement sensors, door contacts)
T8 lamps have a low light emitting efficiency at low temperatures

28. Reduce waste heat caused by illumination
LEDs (E27) can replace incandescent lamps used in deep cooling chambers
Ballasts to be installed outside the cooling chamber
Adjust illumination power to real needs
Adjust illumination times (movement sensors, door contacts)
T8 lamps have a low light emitting efficiency at low temperatures
Automatic deicing might cause 2-3% higher costs, manual deicing is an alternative

29. Cooling circuit
The lower the temperature at the transfer of cooling energy and
The higher the temperature at the transfer of heat
The higher is the capacity requirement

30. Increase evaporation temperature
Step 1: Check evaporation temperatures
Evaporation temperatures should be as high as possible
Step 2: Evaluate design conditions
Temperature differences at evaporator

31. Areas of improvement evaporator
Evaporation temperature is too low, caused by unfavourable circulation of air (stapling of goods, moisture in the room)
Increase evaporation temperature during nights (3.4K) and during weekends (2.1K)
Polluted heat exchanger
Deformed fins (proper air circulation in heat exchanger)
Iced heat exchanger
Fan blads in bad condition, fan does not work
Excessive heat at TV or EV

32. Improve evaporation and condensation temperature
Increase the evaporation temperature by 1 Kelvin increases the performance factor up to 3%
Decrease the condensation temperature by 1 Kelvin increases the performance factor up to 3 %
In case the cooling system has a constant condensation temperature of 40-45°C a variable condensation temperature should be evaluated

33. Variable condensation temperature

34. Example: Variable condensation temperature

35. Recommended condensator temperatures

36. Optimise condensation temperature
Measure the actual condensation temperature or use the temperature indicated in the saturation vapor pressure curve
Preasure can be measured between compressor relay and expansion valve

37. Automatic deicing
Automatic deicing might cause 2-3% higher costs, manual deicing is an alternative

38. Leaks Monitor yearly top-up quantity
Calculate indicator: yearly top up quantity/total refrigerant quantity in %
Benchmark max. < 20%

39. Optimisation

40. Optimisation

41. Example
quick-freeze fruits and vegetables to – 40 °C and storage the final products at – 21 °C.
Operating figures per product:
Before: 750 kWh/t Afterwards: 200 kWh/t. (European standard)
1.875 MWh/a MWh/a
Product: t /a
Energy needs: MWh
Operating time: h/a
2 new chillers á 265 [(2x265)]kW = 530 kW
Investment costs: € (European standard)
Savings per year: 1,3 GWh
Savings per year: €/a
Pay-back period: 4 years