Case Study
Blast Cooler CFD Analysis – Park Cake Bakery, Oldham
Overview
Client: Major UK Bakery Manufacturer
Industry: Food Manufacturing
Presence: CFD analysis, blast cooling design development, airflow optimisation
Project Overview: Newsome carried out a detailed CFD analysis to support the design of new blast cooler rooms at a major bakery production site in Oldham, ensuring freshly baked apple pies could be cooled quickly after production. The modelling confirmed that the proposed system would meet required cooling times and maintain consistent temperature control across all trolley positions within the room.
Newsome was appointed to support the development of new blast cooler rooms at a major bakery production site in Oldham. The cooling system was designed to rapidly reduce the temperature of freshly baked apple pie products following production, ensuring product integrity, food safety compliance and consistent quality across batches. To validate the proposed cooling approach prior to installation, we carried out a detailed Computational Fluid Dynamics (CFD) analysis. The modelling focused on the specific product geometry of the apple pies, which measure 170 mm in diameter and 22 mm in depth, allowing us to simulate realistic thermal performance and airflow behaviour within the blast cooling environment.
The CFD study provided the client with confidence that the system would achieve the required cooling times while maintaining uniformity across all trolley positions within the room.
The Challenge
Rapid cooling of baked products presents several technical challenges. Apple pies leave production at elevated temperatures, typically around 30°C, and must be reduced to safe holding temperatures within a defined timeframe. Uneven airflow can result in temperature variation between trays and trolley positions, creating potential product quality risks and inconsistent cooling rates. Initial airflow modelling revealed a significant risk of air bypass across the trolleys. Without appropriate control measures, cooled air could travel over and around the product rather than being forced through it. This would lead to slower cooling of the central and rear trolley rows, particularly in areas furthest from the direct coil discharge.
Given the scale of the blast room and the density of product loading, it was essential to assess not only airflow distribution but also pressure drop and thermal performance under realistic operating conditions.
CFD Modelling Approach
Due to processing limitations associated with full-room thermal modelling, the CFD analysis was divided into three stages
- Test 1: Full room airflow analysis
- Test 2: Thermal performance on the central row of trolleys
- Test 3: Thermal performance on the right-hand row of trolleys
The modelling environment was simplified to enable efficient processing while maintaining realistic physical parameters. Instead of modelling every individual pie across the entire room, larger thermal blocks were used to represent the combined mass, density and specific heat capacity of the product load. Actual pie dimensions were modelled on selected trays within the third row to simulate worst-case conditions
This approach allowed us to obtain meaningful results while keeping computational time within practical limits.
Airflow Optimisation and Baffle Design
The first CFD test evaluated airflow patterns throughout the blast cooler room. Early simulations highlighted significant air bypass across the trolley stacks. To address this, we tested several baffle arrangements, including front and rear configurations
The results demonstrated that a rear baffle provided the most effective airflow distribution. The rear configuration created beneficial back pressure, forcing cooled air through the third row of trolleys, which would otherwise be the slowest to cool
The pressure drop across the system with the rear baffle installed was measured at 147 Pa, comfortably within the available fan capacity of 210 Pa
This confirmed that the airflow improvements could be achieved without exceeding fan performance limits.
The introduction of the baffle significantly reduced bypass and improved lateral air movement across the extremities of the trolley stacks, particularly in the far-left and far-right areas, which were identified as the weakest flow zones.
Thermal Performance – Central Row
The second CFD stage focused on the thermal behaviour of the central row of trolleys. Test conditions included an initial room temperature of 5°C, airflow of 8.9 m³/s proportional to the full coil capacity, and a coil flow temperature of 0.3°C. The pies were modelled with an initial core temperature of 30°C.
The simulation tracked the cooling curve of a pie located in the lower tray of the rear trolley, representing a worst-case cooling position. Over a 5,400 second period, equivalent to 1.5 hours, the model demonstrated progressive temperature reduction across the product mass. As expected, the third row of trolleys cooled last due to cumulative thermal load pick-up as air passed through the first two rows. However, the airflow improvements delivered by the rear baffle ensured that the cooling profile remained within acceptable limits.
Thermal Performance – End Row
The third test evaluated the right-hand end row of trolleys, representing another worst-case scenario due to reduced direct airflow from the coil face. Interestingly, the cooling profile across this row was more linear. Because the trolleys were partially outside the direct discharge path, air was driven laterally across the stack, resulting in more even thermal distribution across trays. This confirmed that while direct airflow zones are important, controlled back pressure and lateral distribution can play a significant role in achieving uniform cooling.
Engineering Conclusions
The CFD study demonstrated that effective airflow management within the blast cooler is critical to achieving uniform product cooling. Without a baffle arrangement, air bypass would compromise performance and extend cooling times. The introduction of a rear baffle significantly improved airflow penetration and balanced distribution across all trolley rows. Pressure drop remained within fan capability, ensuring that performance improvements did not require oversized plant
Although CFD simulation does not replace physical product trials, it provides strong engineering confidence in the proposed solution. The modelling confirmed that the blast cooling design would deliver the required temperature reduction within the target timeframe, even under worst-case loading conditions.
Outcome and Client Benefits
Through detailed CFD analysis, Newsome provided the client with:
- Validated airflow design prior to installation
- Optimised baffle configuration to prevent bypass
- Confirmed pressure drop within fan limits
- Predicted cooling performance across worst-case trolley positions
- Reduced commissioning risk
By resolving potential airflow inefficiencies at the design stage, we helped ensure that the final blast cooler installation would operate efficiently, safely and consistently from day one.
This project highlights Newsome’s capability to combine advanced modelling techniques with practical engineering insight, delivering robust temperature control solutions for the food manufacturing sector.