Recreational refrigeration: skating on thick ice
There are many styles of refrigeration systems; each serves a useful purpose for a particular application, and none are equally suited for all applications.
Careful consideration must be taken to ensure that you get the system that suits your facility.
The following is a partial list of considerations that can be used as a basis for your customers in their choice of ice rink system.
Facility usage: Is your customer’s primary purpose going to be professional hockey, figure skating, or community recreational skating? Will the facility be used year round or just seasonally? Will it require a cement floor for multipurpose use, or a sand floor for ice sports only?
Ice quality: Will the customer require unwavering perfect ice at all times of the year, even during unseasonably hot periods with heavy usage?
First cost: What is the customer willing to give up to lower costs (ice quality, energy efficiency, etc.)?
Redundancy: How important is it to provide back-up capacity to maintain ice in the event of a breakdown?
Energy efficiency: What is the cost of power? Find out what the exact billing structure is for the area. Is there a demand charge? Is there a time-of-day or time-of-year premium?
Are there any incentives for premium-efficiency systems or gas-driven equipment? And how important is energy efficiency?
Heat reclaim: Does the customer want to recover waste heat for use in the Zamboni, showers, space heating, etc.? Chances are they may not have considered this, and it’s up to the designer to introduce this option.
Environmental requirements: Do any bylaws or restrictions in the municipality restrict the use of calcium chloride, glycol, ammonia, and/or CFCs? Are there any noise-level limitations?
Emergency response crews: Are the fire department and emergency response personnel trained in dealing with emergency situations that might arise at such a facility?
Operator requirements: Do any codes require mandatory supervision for an ammonia or CFC system over a certain size? Are there qualified refrigeration operators in your area?
Maintenance requirements: How much maintenance will the system need, and are there qualified contractors to carry it out in the area?
Ease of operation, maintenance: Is the system laid out in a manner that is conducive to normal operator inspection? Will the operators be trained to fully understand the operation of the system?
Equipment room requirements: What are the requirements for the plant room construction and ventilation? What special safety equipment is required for each class of refrigerant?
Water: Do any water restrictions or poor water conditions exist that might limit the use of evaporative condensers?
Lifecycle: Is the system designed in such a manner that it will have a 25- to 30-year life span without requiring any major alterations?
Indirect systemsAn indirect refrigeration system (Figure 1) is one where a primary refrigerant, such as ammonia or a CFC, refrigerates a secondary refrigerant, such as calcium chloride or glycol, in a chiller. The secondary refrigerant is then pumped to the area requiring cooling, such as an arena floor.
This is by far the most common form of refrigeration applied in the recreational ice industry today.
There are a few exceptions where the primary refrigerant is directly circulated in the arena floor and some installations that apply forced-air refrigeration. These variations are becoming fewer due to maintenance and liability reasons. Therefore, this article will focus on the typical indirect refrigeration system.
The chiller is the dividing point between the primary and secondary systems. This is also where heat exchange takes place between the primary and secondary refrigerants. Heat exchange takes place through the walls of the chiller tubes. There is no intimate contact between the two fluids.
The major components of the primary refrigeration system are the chiller, compressor, and condenser. The major components of the secondary refrigeration system are the chiller, the brine pump, and the arena slab.
Critical charged systemCritical charged systems (Figure 2) are very common in the curling club and arena industry, where ammonia is used as the refrigerant. This application is limited to single chiller applications.
The system is called critical charged because just the exact amount of refrigerant is charged to operate the system. The entire refrigerant charge goes into the chiller during the off cycle, so it is important that the system is not overcharged. An overcharge could cause floodback and damage the compressor. When the system is properly charged, there is very little chance of floodback occurring.
The expansion device is usually a high-side float. A hand expansion valve is usually installed to provide backup in the event of a float failure.
Flooded ammonia systemWhenever a facility has more than one chiller it will have a receiver to facilitate feeding the chillers with ammonia under all load conditions.
In a flooded ammonia chiller, the low-side float control system controls the level of the ammonia on the chiller or low side.
If the level drops in the chiller, the float closes electrical contacts which, in turn, open a liquid solenoid valve, allowing ammonia to enter the chiller through a hand expansion valve.
The receiver also provides a vessel to enable pumping out the ammonia for service procedures.
Miniscrew parallel rackParallel racks have been used for many years in the refrigerated warehousing and grocery industry.
In the past, small hermetic reciprocating compressors were typically used on such systems. The hermetic design resulted in the motor heat being dumped into the refrigeration system and exposed the system to motor burnout problems.
Now, with the availability of the very-high-capacity, open-drive, mini-screw compressor, the very compact parallel racks are capable of much larger applications.
Some facilities employ mini-screw parallel racks with anywhere from four to eight screw compressors on it. This enables close tracking of the refrigeration load and better temperature control. System efficiency is maximized through the use of smaller parallel compressors.
The computer-controlled compressors cycle on and off in response to temperature or pressure variations. In some instances, a variable-frequency drive can be used to vary the speed of the compressors in direct response to the cooling load.
Mini-screw parallel racks can be applied on either direct expansion or flooded chillers, and can employ either ammonia or one of the newer ozone-friendly refrigerants.
Lifecycle costs can be higher as a result of the lighter commercial-duty compressors and the higher number of system components.
Sidebar: Financing program for contractorsVALLEY STREAM, NY æ A new financing program called “Financing Plus” has been introduced by Richtech Inc. that is “specifically designed for installing contractors to assist them in growing their business,” stated Richard J. Graves, president of the firm.
According to Graves, “What this program offers that is unique is that it gives the installing contractor æ without leaving the customer’s house æ the opportunity to close the current sale by obtaining financing approval with an upper dollar limit.”
The program gives the contractor a say in what will be financed and what will not be financed, Graves noted. The company will consider any proposed equipment.
What contractors get with this program are: immediate credit answers by telephone; choice of multiple brands of equipment; and electronic, one-party payments.
The Financing Plus equipment list includes air conditioning units, furnaces, boilers, burners, water heaters, and pool heaters. Manufacturers’ brands currently covered include Trane, Amana, Luxaire, Mitsubishi, Burnham, Lochinvar, Weil-McLain, A.O. Smith, and others.
Graves emphasized that the company will deal only with licensed contractors.
Manufacturers may participate in the program by contributing an annual fee based on total sales, which will eliminate the contractor’s fee.
For more information, contact 516-256-2634; 516-256-2638 (fax).
Sidebar: The history of the Ice AgeThe first use of refrigeration was for the preservation of food. As an industry, it became of commercial importance in the early 18th century, when men would cut large blocks of ice from frozen lakes for storage in icehouses through the summer.
Ice was first made artificially on an experimental basis around 1820, but it was not until 1834 that Jacob Perkins, an American engineer, perfected the process. He was the inventor of what was to develop into our modern vapor-compression systems.
Professor John Gamgee built the first artificial ice rink in London, England, in 1876. His facility was called the Glaciarium and consisted of a 24- by 40-ft ice surface frozen by circulating a refrigerated glycerin/water solution through copper pipes beneath the ice surface. Ether was employed as the primary refrigerant. Mechanical refrigeration systems in this era were still not common.
Due to a warm winter in 1890 creating a severe shortage of ice for food preservation, there was an intensive thrust to develop mechanical refrigeration systems. Since that time, the growth in the worldwide refrigeration market has been phenomenal.
This proliferation of reliable refrigeration systems paved the road for the development of artificial ice rinks throughout the world.
The first artificial indoor ice rink built in North America was the Willows Arena in Victoria, BC, Canada. This state-of-the-art arena was built by Lester and Frank Patrick in 1911 and later became the home of the Victoria Cougars, who went on to win the Stanley Cup in the 1924-25 season.