Thermal Evaluation Of Low & Medium Temperature Refrigerated Facilities
Phillip C. McMullan TSI Thermo-Scan Inspections, Carmel, Indiana
ABSTRACT
The use of non-destructive testing methods to examine the thermal envelope of low and medium temperature refrigerated facilities is the subject of this paper. Commercial refrigeration is similar to the refrigeration that occurs in your household
refrigerator. Simply, it is the process of removing heat from an area and transferring that heat to a place where it makes little or no difference.
Equally important in the refrigeration process are the mechanical refrigeration system components and the thermal envelope of the area being refrigerated. This area defined by the thermal envelope, often referred to as the refrigerated box, is of
critical importance in low and medium temperature applications.
Medium temperature refrigeration typically ranges from 28 degrees F to 40 degrees F with most operating at just above freezing, 32degrees F. A home refrigerator's fresh food compartment is a good example of medium temperature refrigeration. Low temperature refrigeration produces temperatures below freezing. Temperatures can range from just under 32 degrees F, such as in making ice, to low temperature food storage which generally starts at 0 degrees F to as low as –20 degrees F. Frozen meats, vegetables, and dairy products are items preserved by low temperature refrigeration. Extra low temperature facilities used to fast freeze will reach temperatures of –50F.
The use of non-destructive infrared imaging of the refrigerated box provides an invaluable dialogistic tool. The presence of any type of breach in the box can create havoc with the refrigeration system. As the system works to remove latent and
sensible heat from the cooler, the uncontrolled addition of ambient air can cause a number of problems including additional energy consumption, product loss and thermal envelope damage.
This paper will detail the procedures of non-destructive infrared evaluation on two commercial refrigeration facilities and report the findings of these inspections.
Keywords: Refrigerated Facilities, IR inspection, IR thermography, Thermal Envelope
1. REFRIGERATED WAREHOUSE DESIGN
There are two primary components required in the refrigeration process. Shown in figure 1 is a typical mechanical refrigeration system, similar to the ones seen in the facilities, which are discussed in this paper. This two-stage compressor system is designed to cool a freezer for extra low temperature refrigeration with product temperatures as low as minus 50 degrees F. If the application were medium or simply low temperature a single stage compressor would be employed. Regardless of the application, the purpose of this system is to collect the heat within the refrigerated area and remove it to outside the area. It is important to note that the size of the refrigeration system is based on a number of factors. These factors include building design, indoor and outdoor temperatures, and the type and flow of goods expected. Warehouse locations that are subject to high humidity, warm temperatures or manual product handling may dramatically effect the design of the facility.
Figure 2 shows an elevation drawing of the thermal envelope of a typical refrigerated warehouse. The thermal envelope is of critical importance in low and medium-temperature applications. There are four factors of refrigeration load associated with the building envelope. These are transmission losses, infiltration, internal operations loads and cooling of goods received.
Transmission losses involve sensible heat gain through walls, floor and ceiling. These are components that readily lend themselves to infrared inspection. Air infiltration heat gain can occur from several sources, primarily direct in-flow from portions of the building envelope which are not sealed and from passageways. Figure 3 shows what occurs when a freezer door is open.
Phillip C. McMullan TSI Thermo-Scan Inspections, Carmel, Indiana
ABSTRACT
The use of non-destructive testing methods to examine the thermal envelope of low and medium temperature refrigerated facilities is the subject of this paper. Commercial refrigeration is similar to the refrigeration that occurs in your household
refrigerator. Simply, it is the process of removing heat from an area and transferring that heat to a place where it makes little or no difference.
Equally important in the refrigeration process are the mechanical refrigeration system components and the thermal envelope of the area being refrigerated. This area defined by the thermal envelope, often referred to as the refrigerated box, is of
critical importance in low and medium temperature applications.
Medium temperature refrigeration typically ranges from 28 degrees F to 40 degrees F with most operating at just above freezing, 32degrees F. A home refrigerator's fresh food compartment is a good example of medium temperature refrigeration. Low temperature refrigeration produces temperatures below freezing. Temperatures can range from just under 32 degrees F, such as in making ice, to low temperature food storage which generally starts at 0 degrees F to as low as –20 degrees F. Frozen meats, vegetables, and dairy products are items preserved by low temperature refrigeration. Extra low temperature facilities used to fast freeze will reach temperatures of –50F.
The use of non-destructive infrared imaging of the refrigerated box provides an invaluable dialogistic tool. The presence of any type of breach in the box can create havoc with the refrigeration system. As the system works to remove latent and
sensible heat from the cooler, the uncontrolled addition of ambient air can cause a number of problems including additional energy consumption, product loss and thermal envelope damage.
This paper will detail the procedures of non-destructive infrared evaluation on two commercial refrigeration facilities and report the findings of these inspections.
Keywords: Refrigerated Facilities, IR inspection, IR thermography, Thermal Envelope
1. REFRIGERATED WAREHOUSE DESIGN
There are two primary components required in the refrigeration process. Shown in figure 1 is a typical mechanical refrigeration system, similar to the ones seen in the facilities, which are discussed in this paper. This two-stage compressor system is designed to cool a freezer for extra low temperature refrigeration with product temperatures as low as minus 50 degrees F. If the application were medium or simply low temperature a single stage compressor would be employed. Regardless of the application, the purpose of this system is to collect the heat within the refrigerated area and remove it to outside the area. It is important to note that the size of the refrigeration system is based on a number of factors. These factors include building design, indoor and outdoor temperatures, and the type and flow of goods expected. Warehouse locations that are subject to high humidity, warm temperatures or manual product handling may dramatically effect the design of the facility.
Figure 2 shows an elevation drawing of the thermal envelope of a typical refrigerated warehouse. The thermal envelope is of critical importance in low and medium-temperature applications. There are four factors of refrigeration load associated with the building envelope. These are transmission losses, infiltration, internal operations loads and cooling of goods received.
Transmission losses involve sensible heat gain through walls, floor and ceiling. These are components that readily lend themselves to infrared inspection. Air infiltration heat gain can occur from several sources, primarily direct in-flow from portions of the building envelope which are not sealed and from passageways. Figure 3 shows what occurs when a freezer door is open.
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Infrared Refrigerated Warehouse
