So, for example, the 7☌ bin (6.0☌ to 7.9☌) occurs just under 1,000 hours a year in London and just over 700 hours in Strasbourg. Figure 2 shows example binned outdoor dry bulb temperature data for Edinburgh, London and Strasbourg. The range and frequency of outdoor temperatures can usefully be shown by employing ‘banded’ or ‘binned’ data sets. Therefore, for performance testing, so that systems may be compared, BS EN 14511 3 specifies ‘standard’ sets of design/operating temperatures that are used when manufacturers are determining the standardised COP for their heat pump device.įigure 2: Example of ‘binned’ dry bulb temperatures (2K intervals) for Edinburgh, London and Strasbourgīut such COPs will not necessarily reflect the operational performance at conditions that vary from the design condition – which, of course, is most of the time.
#Consider a carnot cycle heat pump cycle with r410a full#
Practically, for a system running at full capacity, the effect of this will be to reduce COP by between 2% and 4% for every 1K increase in the heat output temperature (at the refrigerant condenser) or for every 1K reduction in source temperature (at the refrigerant evaporator). Where the cold source is at T C kelvin (K) and the hot output is at T H K, to maximise the efficiency, the values of T H and T C should be as close to each other as possible. Now, considering that the performance of any ‘heat engine’ is limited by Carnot’s theorem 2 that provides a relationship for the efficiency of a ‘perfect engine’ as So, considering an air to air heat pump application when heating a space:ĬOP H = Useful heat supplied to internal space/Power consumed by heat pump Coefficient of performance (COP) is typically the basis – the higher the COP the better the performance.
When considering the efficiency or effectiveness of a piece of HVAC&R equipment or system, the simple relationship of useful work done/supplied energy provides the basis of all the common measures. Note that this is in terms of unit sales and not cooling capacity – further analysis is in source report 1 The product labels carry the evidence of compliance with the energy performance requirements of Ecodesign directives, by incorporating the numerical indices of seasonal coefficient of performance (SCOP) and seasonal energy efficiency ratings (SEER) – terms that, in the proliferation of performance indices, may cause some uncertainty.įigure 1: Estimated number of sales of air conditioning products in EU. 1 Coincident with this is the implementation of increasingly stringent performance requirements that allow these products to carry a CE mark and, hence, allow their use in the EU.
In Europe, over the next 10 years, growth in unit sales of VRF systems is expected to outstrip growth in other air conditioning systems. This builds on previous CPD articles looking at underlying systems and technology, and considers current measures that underpin the system of energy performance labelling for space air conditioning equipment – and how that equipment is evolving, specifically to overcome areas that can potentially reduce operational effectiveness. The largest growth area in the European market for active air conditioning is in variable refrigerant flow (VRF) systems, presenting an important area of application for building services professionals.
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