Presentation by Ray Gluckman July 9th 2018, Vienna Workshop on energy efficiency opportunities while phasing-down HFCs Cooling Efficiency: technologies Presentation by Ray Gluckman July 9th 2018, Vienna

Presentation Contents Scope for energy efficiency improvements Understanding key efficiency issues efficiency: a step-by-step approach Some examples illustrating: the excellent potential for efficiency improvements impact on capital costs impact of refrigerant selection

Significant Potential to Improve Efficiency

Achieving the technical potential there are plenty of opportunities to improve efficiency what is preventing better uptake of the potential? Lack of understanding how to maximise efficiency Lack of attention / effort during design and selection Lack of monitoring / analysis of performance in operation Simplistic financial considerations that ignore the “big picture”

Some Key Principles during next two sessions we will see many examples of: efficiency improvements related to new equipment (Session II) efficiency improvements related to existing equipment (Session III) to help understand efficiency opportunities what are the key design and operational factors that influence energy use? let’s start by comparing a refrigeration system with moving a weight……

Moving a weight downhill is easy

Moving it back up the hill requires energy

Moving it back up the hill requires energy The energy required depends on: The size of the weight, W The height difference, d (the “vertical lift”) Practical factors e.g. roughness of the ground W d

Refrigeration: moving heat on a “thermodynamic mountain” Weight = a quantity of heat we need to move Vertical lift = temperature we need to move it through = “temperature lift” hotter Temperature colder H

If a colder heat sink is available, cooling is free (heat “rolls downhill”) e.g. tow an iceberg to a warm city for air-conditioning hotter Temperature colder - not realistic or sustainable! H

But, always worth checking for “free cooling” options some good possibilities e.g. data centre cooling, especially if located in cool climates food factories – hot product pre-cooling after cooking cold process streams that need heating e.g. boiling liquid methane at LNG terminals but less helpful for “mainstream” RAC applications e.g. domestic refrigerators bulk storage and retailing of chilled or frozen food room air-conditioning in hot countries

Most RACHP applications – heat has to move “uphill” hotter Temperature colder cooled product or room available coolant e.g. ambient air H

Most RACHP applications – heat has to move “uphill” hotter Temperature colder cooled product or room available coolant e.g. ambient air H

How is the heat moved “uphill”? cooled product or room available coolant H Te

How is the heat moved “uphill”? hotter Temperature colder cooled product or room available coolant Tc H Te

How is the heat moved “uphill”? hotter Temperature colder cooled product or room available coolant Tc H Te

How is the heat moved “uphill”? Evaporating temperature Te must be lower than product temperature Condensing temperature Tc must be higher than the available coolant hotter Temperature colder cooled product or room available coolant H Tc Te

Why is temperature lift so important? RACHP efficiency is VERY sensitive to temperature lift just 1 degree C of extra lift: typically leads to 2% to 4% increase in energy consumption it is very easy to create many degrees C of unnecessary temperature lift through poor design through poor operation incorrect control settings

Recent Press Release – 22nd June 2018 India seeks mandatory 24oC AC setting campaign launched by India’s energy minister Shri R K Singh he advised: every one degree C increase in AC temperature setting saves 6% many commercial establishments use 18 – 21 oC set point saving achievable by simply adjusting a control

Reminder: efficiency rules for lifting a weight The energy required depends on: The size of the weight, W The height difference, d (the “vertical lift”) Practical factors e.g. roughness of the ground W d

RACHP “Heat Mountain” Energy Efficiency Rules Minimise the heat load e.g. free cooling better building structure / insulation less “cold end” auxiliary power (evaporator pumps and fans, lights etc.) less warm air ingress (e.g. doors on display cases) Minimise the temperature lift e.g. bigger heat exchangers changes to temperature set points avoiding fouling of heat exchangers (e.g. frost, oil, debris etc.) Address “practical factors” e.g. high efficiency compressors high efficiency thermodynamic cycle good performance at part load correct choice of refrigerant These are just a few of the many different measures that may influence design or operational efficiency! Some will be described in Sessions II and II

Example of a practical factor: variable operating conditions RACHP equipment designed for a peak condition – the “design point” highest heat load in highest ambient temperature but equipment spends most of life at other operating conditions if designer ignores the “operating envelop” of the system it is likely that much energy will be wasted

Impact of efficiency improvement on costs most efficiency measures have a good financial return for end user any extra capital cost often recovered in 1 – 3 years from energy savings “big picture” issues can significantly improve financial case potential savings in peak demand and requirements for new power stations value of CO2 emission reductions but, end user has no benefits from these savings some efficiency measures achievable with no extra capital cost or reduced cost especially as efficiency technologies become mature or, if heat load reduced, refrigeration system is smaller (e.g. doors on display cases)

Example of Maturing Technology – US Refrigerators from Briefing Note A (figure 7) 75% energy reduction 50% price reduction

Refrigerant Selection good choice of refrigerant is important it is one of the “practical factors” that influence efficiency selection will typically influence efficiency by 5% to 10% other factors are likely to create greater efficiency improvements e.g. heat load reduction minimising temperature lift good maintenance refrigerant leakage must be avoided can reduce efficiency significantly

Concluding Comments many excellent opportunities to improve RACHP efficiency using a structured approach can help maximise potential based on: Minimising the cooling load Minimising the temperature lift Accounting for variable operating conditions Selecting the most efficient refrigeration cycle, refrigerant and components Designing effective control systems Checking operating performance and correcting any faults

Contact Details Ray Gluckman Gluckman Consulting Tel: +44 1932 866344 email: ray@gluckmanconsulting.com Tel: +44 1932 866344 Fact Sheets about Kigali Amendment: www.gluckmanconsulting.com/kigali-amendment/   Fact Sheets about low GWP alternatives to HFCs: www.gluckmanconsulting.com/low-gwp-alternatives-to-hfcs/