Do you want to find out how to to optimise the performance for your refrigeration, air conditioning and provisions plant?
CHILLER PERFORMANCE ANALYSIS
Tradewinds provide owners with state of the art, energy reporting and expertise with hard facts on performance for plant optimisation, trouble-shooting and benchmarking.
Our real time visualisation of performance, gives an early warning if the energy consumption is increasing or validates if optimisation measures give desired savings. We will pinpoint any problems – System Efficiency Index (SEI) and Sub efficiencies high-light deviation from optimal performance and allow benchmarking.
- Commissioning/warranty inspections
- Site & Factory Acceptance Tests
- Performance Inspections
- Unbiased, independent performance validation
- Energy optimisation
- Troubleshooting and fault correction
- Extending plant life
- Preventative maintenance and service
- Continuous monitoring
What values are recorded and what values are calculated?
- Suction pressure at Compressor inlet
- Discharge pressure at Compressor outlet
- Suction temperature at Compressor inlet
- Discharge temperature at Compressor outlet
- Liquid temperature upstream of expansion device
- Voltage on all three phases
- Current on all three phases
- Inlet temperature to Evaporator
- Outlet temperature from Evaporator
- Inlet temperature to Condenser
- Outlet temperature from Condenser
The following values are calculated:
- Power input – kW (per phase and total)
- Power factor
- Refrigerant mass flow rate – kg/s
- Cooling capacity – kW
- Heat of rejection – kW
- Compressor isentropic efficiency – %
- System COP – cooling
- System COP – heating
- Superheat – K
- Sub-cooling – K
- Expansion valve function/adjustment
- Precision refrigerant charging
- Compressor efficiency
- Evaluating heat exchanger performance and secondary flow rates
- Verification of control functions and system protection
- Evaluation of Performance:
Capacity, COP/EER and electrical power/power factor
The above measurements allow all performance parameters to be calculated and displayed, including:
- Cooling and heating capacity (+-7%)
- Electrical power input (+-2%)
- Coefficient of Performance / EER (+-5%)
- Compressor isentropic efficiency
- Evaporating / condensing
- pressure and temperature
- Discharge temperature
- Superheat / sub-cooling
- Entering and leaving evaporator air / water temperature
- Entering and leaving condenser air / water temperature
- Temperature differences and flow rates in evaporator / condenser
MEASURE IMPORTANT OPERATING CONDITIONS
Easy To View Performance Indicators
Sample Data – 24 Hrs Pre-optimization
Sample Data – 24 Hrs Post-optimization
M/Y AVIVA – GERMANY – EXPERT WITNESS SURVEY
This project had escalated between the client and the shipyard so Tradewinds were asked to review the operation of the main chiller as an independent 3rd party. By monitoring the performance over a period of time, we were able to identify and resolve the issue immediately.
95M SUPERYACHT – SPAIN – PERFORMANCE SURVEY
We were asked to review the performance of the 750Kw Chiller onboard a 95m Superyacht. The chiller was made up of x4 individual circuits and each circuit was analyzed separately. We noticed that one of the circuits was running with a higher discharge pressure than the others and this prompted further investigation, as it was causing the compressor to work harder which created unnecessary load on the chiller.
Further investigation into the problem found that the 3 way bypass valve was stuck in the mid position and restricting the amount of water flow through the condenser. This information was shared with the engineering team, who agreed they would replace this valve.
As a very basic overview of the additional fuel costs that this fault is causing, a simple calculation can be made as follows:
Note: Obviously the load of the yacht is constantly changing but lets take a look at the full load scenario
310Kw Full Load of the Yacht
100Kw due to AC load
Engine burns 100L/Hr in fuel
100L divided by 310Kw = 0.322
0.322 x 100 = 32L/Hr
9% saving of 32L/Hr = 2.9L/Hr saved
2.9L/Hr x 24Hrs x 365Days = 25,404L/Year
25,404 x 0.50Euros (Diesel) = a saving of 12,702Euros per year
M/Y NORTH STAR – SUPERYACHT – SPAIN – PERFORMANCE ANALYSIS
MAIN A/C CHILLED WATER PLANT
A performance analysis test was carried out on both circuits of the main AC Chiller and the following issues were found:
- Chiller short cycles every 3 minutes which is approximately 20 starts per hour. Bitzer recommend no more than 6 starts per hour
- PRV’s are 10years old and need to be replaced
- Liquid line filter driers should be replaced
- Carel control system is now obsolete
- Circuit 1 has liquid refrigerant in the oil sight glass
Based on the information from the test, I suspected that circuit 1 was overcharged with refrigerant and the high suction pressure was causing the system to load up fully and therefore cause the short cycling of the compressor. I recovered the refrigerant and removed a total of 64Kg of R407C when actually each circuit only requires 35Kg. I charged the correct amount back in each circuit and monitored the performance again. The performance has now stabilized and the chiller is working efficiently whilst only requiring 2 starts per hour depending on the load. To assist with this, I changed the deadband on the chilled water leaving temperature setpoint from 2’C to 5’C. There is no need to start the chiller again at only 2’C above setpoint and 5’C deadband is more in line with industry practices.
115m SUPERYACHT – DUBAI
In January 2020, Tradewinds carried out a Performance Analysis Survey on the chillers and provisions refrigeration system of a 115m+ Superyacht. Our client had been experiencing ongoing problems with one particular circuit tripping out of high discharge temperature during the summer months and also wanted an overall review of all systems. After connecting our specialist test equipment, we were able to easily monitor the chiller parameters (including kW Cooling, pressures, temperatures, flow rates, COP, Power consumption, voltage, amperage and a host of other information in great detail) and identify what the situation was. All circuits were run up on full load and summer conditions were simulated to ‘stress’ the machine and identify the fault. After watching the trending information, we were able to identify the fault and therefore provide the right solution.
During the survey, we also noticed that the original R404A charge had been replaced with R134A. Whilst this might be a lower GWP refrigerant and therefore a good option as a retrofit refrigerant, we analysed the performance of the chillers and found them to be operating at 77% of the original design. Using the Bitzer software, we also compared the design difference in cooling capacity when using R134A and found it to be 57% less than R404A. This is a massive drop in cooling capacity and one of the major reasons why they are struggling to maintain the temperature during the summer months. The onboard engineer, then calculated the savings in fuel costs over a year and found that they would burn 146000Kg less fuel and providing a cost saving of USD$100,000
After completing the survey, our report was provided, explaining our findings and offered recommendations to improve the performance of the refrigeration equipment. Most of these recommendations were able to be completed by the onboard Engineers and we continue to support our client with consultancy advice and our marine refrigeration training courses.
We requested Stuart from Tradewinds to attend our vessel after seeing his work on LinkedIn. At the time we had no support company for our refrigeration/AC equipment and it was something I wanted to set up. Stuart attended for a week to carry out an overall efficiency survey of our equipment, studying the original designs, navigating the un-documented modifications, fully familiarizing himself with the systems and carrying out the efficiency survey. Stuart found a number of deficiencies and found the cause of an ongoing issue that had one of our chiller compressors tripping un expectantly. We currently operate in an environment beyond the design limitations of our system (35 degree C seawater) really testing our plant, failures is not an option over the summer so it is vital the system is running well. Stuart looked into improvements on our request finding that modifications in the past re-gassing from R404a to R134a was a mistake, reducing our overall capacity to 67% of the original, changing to R407C can bring this back to 90% of original, the savings in fuel would be significant in only a short space of time. After this survey Stuart and Tradewinds are now in a position to assist us remotely and will be my first point of call for future works and refits. I was surprised at the issues we had been running with unknowingly and after correcting these issues how improved our plant is. I would highly recommend this survey for anyone operating AC and refrigeration plants, Stuart is a natural teacher, and I thoroughly enjoyed spending time with him on the systems.