Time to replace your old chiller
Save Money and energy from replacing Your Chiller
How to Audit and estimate your energy and cost by replacing your old Air Cooled Chiller or Air Cooled Chillers. How to get most of it by replacing your old chiller, which hit management pocket very badly.
Chiller is the heart of any Building, Office or Hospital which is very expensive as well as it consumes almost 40% of total energy. Replacing a chiller is a very critical decision of the management and very challenging for the Chief Technical Officer to make management understand the requirement.
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Why do Chillers need to replace?
A typical chiller has a life span of around 10 to 15 years. A very critical decision to change the chiller based on its age, compressor performance, the criticality of the application, Operation and maintenance cost of the chiller.
Chiller efficiency and maintenance are playing a key parameter for replacing an old chiller. Also technological advancement and upgraded spares like compressors make the most economical to replace a chiller. A general study shows around the replacement of old chiller reduces 30% energy saving and almost 70% saving in operation cost.
Key Points to drive when you should change your chiller.
01. The chiller plant is almost 10 to 15 Years of age.
02. Huge maintenance cost for the chiller.
03. Very old technology.
For example, Oil-Free chiller (magnetic bearing chiller) maintenance is only to clean the spare parts, dust off the VFD boards, tightness the electrical connection. No replacement of huge amount of oil, as this is not oiled compressor. Only Capacitors need to replace at an interval of 5 years (if required). No major tear down or overhauling for the compressor.
Values to identify the energy-saving on replacing chillers.
There are many types of calculations or procedures to identify chiller performance. The most common and easy mechanism is identity and compares the IPLV (Integrated Part Load Value) and NPLV (Non-Standard Part Load Value).
These values easily identified in the chiller brochure or can be shared by the technical / sales team. This is the most common key factor for identifying any chiller and its performance.
Definition of IPLV/NPLV
The IPLV or NPLV is the weighted efficiency of a chiller operating at 100%, 75%, 50% and 25% against a typical amount of time per year at specified conditions defined by ASHRAE in AHRI Standard 550/590. When a chiller is unable to operate at these specifications then it will be rated as NPLV.
We can differentiate IPLV in two ways.
01. Calculated based on COP / EER.
02. Calculated based on kW/TR.
Both are stated by the manufacturer, slightly different ways to calculate the values.
IPLV Calculated based on COP/EER :
For example, a chiller with a reciprocating compressor might have an IPLV COP rating of 3.2 whereas an equivalent Daikin Magnetic bearing chillers might have an IPLV COP rating of 12.12 As COP is based on kW of electricity input per kW of cooling output then a higher COP rating means a more energy-efficient chiller. So the Daikin Chiller is 4.0 times more efficient than the reciprocating. (12.12/3.2)
IPLV Calculated based on kW/TR :
When the IPLV is rated for kW/TR then a lower value means more energy efficiency. The same reciprocating chiller might have an IPLV kW/TR of 0.7645 whereas the Daikin might have an IPLV kW/Ton of 0.3398 so the Daikin is 2.25 times more efficient. (0.7645/0.3398)
Estimate your Chiller Performance (Energy Audit)
This is recommended that you should use a building energy analysis program that is compliant with ASHRAE standard 140. This can create a model with weather data where can be seen how chiller will react in the situation.
However, if you want to check the performance and rough estimation of annual consumption for comparative purposes, then the below calculation will help you to estimate the performance.
• Chiller operating at mainly full load kW/Ton
• Chiller operating mainly at Full load COP
• Chiller operating mainly at part load kW/Ton
• Chiller operating mainly at part load COP
• Chiller based on actual cooling load logs kW/Ton
• Chiller based on actual cooling load logs COP
Chiller running at a Full load
If your chiller running at a full load, here is the calculation for you.
To calculate the estimated energy consumption simply multiply the rated capacity of the chiller Tons with the efficiency at full load being in kW/Ton and multiply this by the annual run hours.
For example, if we compare a reciprocating chiller with a full load efficiency of 0.83 kW/TR to a scroll chiller with an efficiency of 0.6 kW/Ton, both rated at 500 Tons capacity and run for 3000 hours per year. We see that the reciprocating chiller consumes 1,245,000 kWh/y whereas the scroll chiller consumes 900,000 kWh.
Alternatively, if you have the COP rating you would simply divide the chiller capacity, rated in kW, by the COP then multiply this by the operating hours per year. So to compare two chillers rated at 1758 kW. The first, a reciprocating chiller with a COP of 4.24 and the second a scroll chiller with a COP of 5.86, both units run for 3000 hours per year, then the estimated annual consumption would be equal to 1,245,035 kWh for the reciprocating chiller and 900,207 kWh for the scroll chiller.
Variable load chiller.
If you have a chiller with a variable load, which is far more likely, then you can use the following method.
If you have the IPLV kW/Ton value then you can use the following method. To calculate the estimated annual kWh consumption then take the cooling capacity Ton rating of the chiller and multiply this by the annual operating hours per year then multiply this by the efficiency IPLV kW/Ton value and then multiply this all by the average loading factor which is likely around 0.6.
For example, we’ll compare a Daikin chiller with an IPLV of 0.34 to a reciprocating chiller with an IPLV of 0.65. Both units are rated at 250 tons with an average load factor of 0.58 and operate for 5000 hours per year.
So, if we drop the numbers in, you can see the Daikin comes out at 246,500 kWh/y whereas the reciprocating chiller comes out at 471,250 kWh/y resulting in a saving of 224,750 kWh/y.
If you have the IPLV COP value then you can use the following method. To calculate the estimated annual kWh consumption, take the cooling capacity rated in kW and multiply this by the operating hours per year, then divide this by the efficiency IPLV value and then multiply this by the average load factor.
For example, we’ll compare a Daikin chiller with an IPLV of 10.35 to a reciprocating chiller with an IPLV of 5.409. Both have an average load factor of 0.58 and a run time of 3,000 hours per year.
To calculate this we need to take the chillers rated capacity (kW) and multiply this by the run hours per year, then divide it by the IPLV COP efficiency and multiply this by the average load factor.
Dropping these numbers in we can see the reciprocating chiller consumes 343,957 kWh/y per year whereas the Daikin consumes 153,000 kWh/y.
Sample ROI Calculation
01. The Engineering Mindset: https://theengineeringmindset.com/