Page 29 - Climate Control News September 2019

Jensen said to comply with international trea- ties, Australia must implement RACHP solu- tions that not only eliminate dependence upon HFC refrigerants, but also reduce energy con- sumption and reduce indirect emissions at the same time.
“One solution that can achieve this is low charge, central type, NH3 based refrigeration systems with dry expansion (DX) refrigerant feed,” he said.
To demonstrate his point, he presented a case study which involved the retrofit of an older, in- dustry standard, air-cooled R404A refrigeration system with electric defrost which was replaced with a modern centralized, low charge NH3 sys- tem (LC NH3).
When older HFC systems are replaced with transcritical CO2 (TC CO2) systems, Jensen said the improvement in annualized energy perfor- mance in Australia is somewhere between 0 and 20% depending on the jurisdiction.
With this LC NH3 system the recorded spe- cific energy consumption (SEC) for that cold storage facility was reduced by 57 to 59% meas- ured in kWh/m3*a.
“This presents a very serious challenge to the proponents of TC CO2 systems, because LC NH3 beats the energy performance of those by about 40%.This is recorded and there is no CO2 equator here,” Jensen said.
“The extra capital cost of the LC NH3 system compared with TC CO2 will be returned in about four years based on energy savings alone. In ad- dition, the LC NH3 plant has twice the technical life of a TC CO2 system.
“What is of particular interest here is that the investment in a new LC NH3 system to replace an older HFC system is often cash flow positive from day one. This is because the value of the en- ergy cost savings exceed the finance costs.
“All the investor needs is a balance sheet that is acceptable to the financier. If the investor can continue to pay the same off on the loan for the new LC NH3 plant that he/she paid per month for electricity consumed by the old plant, then
“IT'’S NOT JUST ABOUT HIGH AMBIENT TEMPERATURES THERE IS A LOW LEVEL OF AWARENESS ABOUT NATURAL REFRIGERANT-BASED SOLUTIONS IN AUSTRALIA.”
the new LC NH3 system will be fully owned after 5-7 years depending on the size of the system and the unit electricity cost,” he said.
“This means that those who own a dilapidated HFC plant can get out of HFC’s and increase profits from day one by investing in LC NH3. That is like someone paying you to replace your old air conditioner with a new one.”
CASE STUDY
The plant that is the subject of Jensen’s case study was a relative small dual stage, ammonia refrigeration system servicing a refrigerated storage/distribution facility owned and operated by a food service company.
In the first instance, Jensen said a decision was made to remove the wall between the two freez- er rooms and relocate the air coolers.
MAIN: Case study results show investment in a new Low Charge NH3 system to replace
an older HFC system is cash flow positive from day one.
LEFT: Scantec Refrigeration managing director, Stefan Jensen
“Prior to this decision, air circulation between the two freezer rooms by mechanical means was planned but with the removal of the wall, this be- came unnecessary,” Jensen said.
Secondly, the dividing wall between the two segments of the Chiller were also removed; this was in order to limit the number of air coolers required in that particular area to one.
“The prefabricated dual stage, central ammo- nia plant room was located immediately adja- cent to the freezer evaporators to keep NH3 pipe- lines relatively short.”
The warehouse is situated in Mackay, North Queensland and the highest recorded dry bulb temperature for the region is 36.9°C.
The HFC based refrigeration plant servicing the facility ceased operations in 2015.
Discussions commenced in the fourth quarter of 2017 to replace the plant with the new installa- tion completed in August, 2018.
Jensen said the previous system comprised a number of low temperature Bitzer air cooled con- densing units suitable for outdoor installation and one medium temperature condensing unit of unknown make. These were connected to 10 matching commercial evaporators with the low temperature units arranged for electric defrost.
“The refrigerant was R404A in the low tempera- ture segment. The refrigerant used in the medium
LEFT & ABOVE: The warehouse is situated in Mackay, North Queensland.
Natural Refrigerants
CLIMATE CONTROL NEWS SEPTEMBER 2019
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