Refrigeration Capacity
Size the product freezing load first — it is the number every other decision in a QFM project depends on, and the number most often understated.
What the Freezing Load Includes
The QFM freezing load is built from fresh product throughput in pounds per day.
The QuickFreeze freezing load calculation starts from one input — how many pounds of fresh product enter the system per day — and builds the refrigeration requirement from the product itself plus the heat the QFM system adds to the room. Five components make up the calculated load:
| # | Load component | What it covers |
|---|---|---|
| 1 | Sensible heat, above freezing | Cooling the product from its entering temperature down to its initial freezing point. |
| 2 | Latent heat of fusion | Freezing the product’s water fraction — typically the largest single component of the load. |
| 3 | Sensible heat, below freezing | Pulling the frozen product from its freezing point down to the final core target temperature. |
| 4 | QFM fan heat | 550 W per pallet position. Each position has its own EC fan running inside the refrigerated envelope; every watt ends up in the evaporator budget. |
| 5 | Peak factor | A 5% factor applied to the peak design load to cover real-world variation in product entering conditions and loading patterns. |
Throughput math is straightforward but unforgiving: pallet positions ÷ cycle hours × 24 = pallets per day, times pallet weight = pounds per day. Worked at a 60-hour design cycle with 2,000-lb pallets:
| Pallet positions | Cycle time | Pallets per day | Throughput |
|---|---|---|---|
| 720 | 60 h | 288 | 576,000 lb/day |
| 900 | 60 h | 360 | 720,000 lb/day |
| 1,020 | 60 h | 408 | 816,000 lb/day |
Design pitfall — assumed pallet weight. Pallet weight has a very significant impact on refrigeration load and on the refrigeration equipment needed. Verify the real weight; do not model a nominal 2,000 lb pallet that ships at 2,300. Packaging matters too — refrigeration contractors commonly add about 300 lb of packaging per pallet on top of the product weight, carried at a different heat-load factor than the product itself.
For early-stage screening, these per-pallet refrigeration constants are the same ones the Blast Ready Report uses:
| Product | Design pallet weight | Refrigeration load |
|---|---|---|
| Chicken | 1,650 lb | 0.93 TR per pallet |
| Beef | 1,800 lb | 0.68 TR per pallet |
| Pork | 1,600 lb | 0.45 TR per pallet |
A companion rule of thumb for the room itself: base room load runs about 1 TR per 700 sq ft of freezer floor — subtract that from installed evaporator tonnage before counting capacity as available for blast freezing.
Temperature Difference (TD) and Freeze Time
The gap between blast-air temperature and the product target temperature is the driving force of the freeze.
TD is the difference between the room / blast-air temperature and the product’s target core temperature. The larger the TD, the faster heat leaves the product. As the core approaches the air temperature the rate slows, so a small TD stretches the tail of the freeze curve out dramatically.
Recommended minimum TD: 5°F. Keep the blast-air temperature at least 5°F below the product target core temperature. Below a 5°F TD, time-to-freeze rises exponentially — the last few degrees of pulldown can take longer than the entire freeze before them, and at zero TD the product never reaches target. The Heat Load Calculator flags a small-TD condition for you.
Run the Numbers: the Heat Load Calculator
The calculator is the primary sizing tool — same methodology QuickFreeze engineering uses.
The Heat Load Calculator computes the QFM product freezing load from your throughput, product type, entering and target temperatures, and pallet data. Run it before any layout work — the output tells you whether your refrigeration plant can support the position count you are sketching. If you would rather have QuickFreeze engineering run it, fill out the heat load questionnaire (MKT-229) above the red line and send it in; you get back the calculated load with the assumptions stated.
What the Calculator Excludes
The calculator sizes the product load. It does not size your room.
The following loads are real, belong to the room designer or refrigeration contractor, and are not in the calculator output:
| Excluded load | Why it matters |
|---|---|
| Building envelope / transmission | Heat gain through walls, roof, and floor — construction- and climate-specific. |
| Infiltration | Door-opening load. Blast operations raise turns, which raises door openings — see below. |
| Room evaporator fan loads | The room’s own air units add motor heat, separate from the QFM fans. |
| People, forklifts, lighting | Occupancy loads scale with the higher traffic a blast room sees. |
| Defrost-runtime correction | Capacity lost to defrost cycles must be backed out of nameplate tonnage. |
For a full-room design — particularly a retrofit — request a Blast Ready review. To run one, QuickFreeze needs: (1) an equipment list of every piece of refrigeration equipment including model numbers and capacities, (2) the P&ID, and (3) a floor plan, CAD preferred. Racking drawings and a mass balance (from your PSM documentation, sometimes called a mass-energy balance) make the review materially better. The output is a per-room Blast Ready Report; the residual gap is almost always racking detail, which the site visit closes.
Blasting Into an Occupied Warehouse
QFMs convert storage rooms into blast rooms — four effects to design for.
Adding blast capacity to a holding freezer changes how the room behaves, and the heat load is only the start:
| Effect | Design response |
|---|---|
| More turns → more door openings → more infiltration | Blast positions see far more traffic than storage positions. Re-run the infiltration load at the new door-opening frequency; consider zoning — evaporators nearest the dock door realistically cover fewer pallet positions (a field design carried 120 positions per dock-side zone vs 140 for far zones). |
| Room temperature vs product target | Hold the room at least 5 °F below the product target temperature. Freezing to 0 °F on a 24-hour cycle usually means running the room at −10 °F or colder. |
| Airflow and return-air paths | Direct evaporator discharge air into the drive aisles where the QFMs pull from — it is the best arrangement for QFM performance, and turning air units 90° over aisleways is acceptable refrigeration-wise (verify the structural attachment). |
| QFM fan heat | The per-position EC fans add 550 W per pallet position of heat that did not exist when the room was storage-only. It must be in the evaporator budget, not discovered after commissioning. |
Freeze-Cycle Reality
Validated field cycle times — use these to sanity-check the cycle assumption in your throughput math.
| Product | Room air temp | Validated result |
|---|---|---|
| 1,650-lb chicken pallet (typical design basis) | design room | ~23 h cycle |
| 10-kg chicken leg quarters | −12 °F | Frozen in under 24 h |
| 40-lb boxed chicken (MSC) | −8 °F | 26.5 h average |
| 40-lb boxes, 18% solution product | −4.8 °F | 0 °F core in 33 h |
| 40-lb boxes, 16% solution product | −8.1 °F | 19.3 °F core at 24 h — cycle still finishing |
Design pitfall — ignoring solution percentage and room temperature. Marination/solution percentage materially extends freeze time, and a warmer room stretches it further — the spread above (23 h to 33 h on comparable case weights) is driven almost entirely by those two variables. Collect sodium/solution content, case weight, and the pallet stack pattern (cases per layer, spacers) when gathering product data. Best practice for anything unusual: freeze a test pallet of the actual product, and plan on roughly 4 weeks of data collection to establish true system capability.
Documents
Permanent URLs — always the current revision.
Heat Load Questionnaire
The data set needed for QuickFreeze engineering to run your heat load: product, throughput, temperatures, pallet detail.
QFM Spec Sheet
Unit dimensions, mounting, swing-seal envelope, and electrical interface for the QFM itself.
Blast Ready Report
Per-room capacity review: evaporator tonnage minus base room load equals QFM potential. The retrofit starting point.
Capacity FAQ
The questions engineers actually ask at this stage.
What pallet weight should I model?
The real one — weigh it or pull it from shipping records. Pallet weight has a very significant impact on refrigeration load; a screening model often assumes 2,000 lb, but design proteins run 1,600–1,800 lb and packaging adds roughly 300 lb per pallet at its own heat-load factor. An assumed weight is the most common source of an undersized plant.
Does the Heat Load Calculator size my room refrigeration?
No. It sizes the product freezing load plus QFM fan heat and the peak factor. Envelope, infiltration, room evaporator fans, occupancy, lighting, and defrost correction are excluded and belong to the room designer. For the full picture, request a Blast Ready review with your equipment list, P&ID, and floor plan.
How cold does the room need to be?
At least 5 °F below your product target temperature — and colder buys cycle time. If the target is 0 °F within 24 hours, plan the room at −10 °F. The validated examples above show what happens at −4.8 °F: the same case format that finishes in ~26 h at −8 °F takes 33 h.
Can evaporator discharge air be directed into the drive aisles?
Yes — it is the preferred arrangement for QFM performance, since the per-position fans pull air from the aisle. Rotating air units 90° to discharge over aisleways has been confirmed acceptable from a refrigeration standpoint; have the structural attachment checked.
How firm are published cycle times?
The table above is validated field data, but solution percentage, case weight, stack pattern, spacer type, and room temperature all move the number. For any product without direct validation history, freeze a test pallet and let about 4 weeks of logged cycles establish the true capability before you commit a throughput guarantee to it.
Right-Sizing Your System
How many QFM positions you actually need — and why position count alone is the wrong way to compare blast systems.
Sizing a QFM system is a demand question, not just “how many pallet positions fit.” It comes down to how much product has to be frozen per day — today and as the operation grows. The variables that move the answer:
- Present and future throughput. Size for the demand you expect to grow into, not just today’s volume.
- Air temperature (TD). Colder blast air — a larger temperature difference, covered above — freezes faster, so the same throughput needs fewer positions.
- Arrival spikes. Product rarely arrives evenly. Peak-day surges, not the daily average, set the position count needed to avoid a backlog.
- Product mix. Pallet weight, packaging, and target temperature change cycle time, and therefore how many turns each position delivers per day.
Don’t compare on pallet positions alone. Competing blast systems are often compared purely on the number of pallet positions required. QFM’s dynamic cycle-time tools — most notably AutoSense, which ends each cycle the moment the core hits target instead of running a fixed worst-case time — turn every position more often. More turns per position per day means you need fewer positions for the same throughput, so a position-to-position comparison understates QFM’s real capacity.
Get Your Load Number
Five inputs, one answer: can your plant support the blast capacity you want?