Chillers or also known as refrigeration machines are widely used in many industries. Their main function is to remove heat in order to maintain comfortable temperature within the rooms. Nowadays, there are many types of chillers used for various purposes. Costs for installation of such system and its further operation are pretty high. It is also obvious that the customer is interested in its stable and uninterruptible work. What are the common issues owners of buildings with chillers installed face and how can they be avoided?
Issue: Unstable operation of chiller
Cause: Partial load
Power calculation for determining cooling capacity is normally carried out taking into account the highest air temperature in the summer. Such high temperatures are irrelevant during the day as the air temperature drops at nights and on cooler days. Therefore, generation of the cold for a building in relation to temperature fluctuations at different times of the day and under various weather conditions is generally higher than it is necessary. In this case we can see partial loading of the chiller. It further results in its decreased efficiency in general. It should also be noted that type of compressor used and the type of capacity regulation are important for efficiency.
There might be another problem when loading on cooling system at a certain time is below the minimum values of cooling capacity of chiller itself. In this case, we may see cyclic switching off and on and it also affects efficiency of the system. This often becomes the main reason of failure of automatic control system because it wears it out. As a result, you will face increased operating and maintenance costs of the chiller. It is extremely expensive for the owner of facilities.
Resolution of the issue
In this case, it is advisable to install two chillers with different or identical capacities. At the same time, it is necessary to select equipment according to its capacity and considering the needs of the building in cooling throughout the year.
At this point, the first chiller will have high efficiency refrigeration with most typical loads over a long period of time. The second chiller will generate additional cold during peak loads.
Efficient operation of the cooling system under this approach will require correct calculation of building’s need in cold throughout the year. When calculating, it is necessary to take into account the following factors: heat generation variables within the building, changes in the air temperature outside, temperature of cooling water that circulates in the system, load of building, etc.
Issue: Defrosting and damage to heat exchanger of the chiller
Cause: Not appropriate maintenance of equipment
Heat exchanger is one of the key components of the chiller. Working fluids of the system constantly run through its channels. Leakage between circuits of heat exchanger is one of the most common failures. Untimely or incompetent maintenance of the chiller may cause defrosting and damage to heat exchanger and chiller.
When micro leakage occurs, water enters refrigeration circuit that results in irreparable damage for the compressor. After a while, refrigeration compressor will be completely flooded and the chiller fails to operate.
Resolution of the issue
It is important to take preventive measures for safety of the equipment and mechanisms of the chiller. Professional preservation of the system for winter period will be needed in this case. To do this, it is necessary to stop the chiller. If it is water based coolant, drain it completely from the heat exchanger and pipelines. After draining water from heat exchanger (especially true for plate type), pour antifreeze into it for the winter storage period as remains of even a small amount of water would expanding during crystallization may damage evaporator and refrigeration machine. As we can see, “pennyworth” but timely measure will allow you maintain your equipment in good condition and avoid unnecessary high costs.
Most of malfunctions that result in the failure of the heat exchanger and compressor, shutdown of the chiller and costly repairs, may be identified and solved at the very initial stages. ARTS specialists perform both installation/repair of chiller equipment and carry out complex diagnostics of systems. Scheduled diagnostics is recommended at intervals of at least once a year for efficient operation of the chiller.
TOP mistakes when choosing your chiller
Specialists of companies that perform servicing HVAC equipment very often have to correct errors that customers made themselves when choosing and installing their chillers. We have collected the most common ones. Following the simple rules will help you to avoid unpleasant situations related to equipment failure, unnecessary energy costs and additional expenses for repairs and maintenance.
Purchase of ready chiller without professional calculations
Nowadays you may find a wide range of ready-made chillers at the market. At first glance, such offers seem to be more attractive than searching for equipment that fits your individual needs.
Conveyor chiller is unlikely to provide uninterrupted maintenance of comfortable room temperature. When selecting a chiller for efficient cooling, some nuances should be taken into account as follows: features of production and technical processes within the facilities, boiling temperature, temperature on evaporator, coolant consumption, condensation temperature and some other parameters. It is very unlikely that a random chiller fits such features.
Professional companies that work with refrigeration equipment may be a perfect choice when selecting features of a chiller for your specific needs. ARTS specialists have 20 years of experience in this field and therefore perform precise calculations and selection of equipment based on specific parameters of buildings and your specific needs.
Purchase of used equipment
Some owners of buildings decide to buy a used chiller in order to save money instead of purchasing the brand new. Common problems they may face during operation of cooling equipment are leaking oil, noise in compressor, failure of fans or heat exchangers. Repair of such equipment is expensive. BY comparison, new high-quality equipment that is selected by specialists operates smoothly and does not caus such problems.
The higher the pumping pressure, the better
“The higher pressure is, the greater is cooling capacity” is wrong statement. When installing large pump to increase the pressure, it is necessary to clamp it to reduce pressure. This will result in increased energy consumption of the pump.
In order to prevent such mistake, contact professionals that will design the system. This is when the equipment is selected in accordance with existing parameters. We also recommend using “smart” pumps that have frequency converters as they save energy and have longer service life.
Each owner of a facility willing to purchase and install of a chiller should realize that any minor mistake in its choice, its unprofessional design of the system may result in serious consequences. Do not play with your nerves and do not waste your money on excessive consumption of electricity, costly repairs of the expensive equipment. Just trust professionals!
In the next issue we will talk about some details for design of chiller systems.