<![CDATA[Noise reduction for HVAC and industrial systems

<![CDATA[Noise reduction for HVAC and industrial systems - Blog]]>Sat, 18 Jan 2025 06:02:30 +0100Weebly<![CDATA[installation distances between refrigeration systems and heat pumps.]]>Sun, 05 Jan 2025 19:38:00 GMThttp://www.forcotech.com/blog/nstallation-distances-between-refrigeration-systems-and-heat-pumpsMore and more often, we are forced to plan several refrigeration systems or heat pumps in a relatively small area.

In most cases, the arrangement of the system is therefore planned on the basis of the available space.

This one-sided focus can have drastic effects on the free air exchange of the systems, both for the supply air and the exhaust air of the systems.

The architectural and atmospheric conditions around the systems can have a massive impact on their performance. Recessed roofs and walls, for example, can have a negative impact on the air flow due to turbulence. On the air outlet side, recirculation of the exhaust air can lead to a massive loss of system performance due to the higher air inlet temperatures during heat transfer.

Another factor that is not often taken into account is the distance between the units, which not only influences the air flow, but can also lead to a massive recirculation of the exhaust air depending on the wind conditions. If the systems are installed one behind the other, the advantage is that the air flow remains free on all sides (Fig. 1). If the systems are arranged next to each other, it must be taken into account that, for example, with 3 systems, both sides of the air flow with the centre system are in the intake area of the two opposite systems (air shadow). Depending on the air volume of the systems, the distance between the systems must therefore be planned to be considerably greater than if they are installed one behind the other. (Fig. 2).

The design of the systems is also a decisive factor in the arrangement of the systems. A particular example are systems in table-top design, often drycoolers whose condensers are usually installed a short distance from the floor (Fig. 3). If such units are installed too close to each other, the air flow of the supply air is negatively affected during simultaneous full-load operation, i.e. the inflow area is too small, which can lead to a reduction in performance of the units of up to 30%. One way of installing the units closer together is, for example, to elevate them on a grating to increase the air inflow area from below (Fig. 4). An additional advantage of elevation is the greater ground clearance which, depending on the nature of the substrate, e.g. soil or grass under the grille, also has a positive effect on the delta T between the supply air temperature and the cooling temperature, as soil heats up significantly less in direct sunlight than a concrete substrate, for example. In terms of sound, soil also has the advantage of absorbing sound and not reflecting it, as is the case with a sound-reflecting surface such as concrete.

]]><![CDATA[January 05th, 2025]]>Sun, 05 Jan 2025 19:31:22 GMThttp://www.forcotech.com/blog/january-05th-2025Ejectors in heat pumps
Ejectors are innovative components that are used in heat pumps to significantly increase their efficiency. They enable a significant increase in efficiency by optimising and partially recovering the compression work required in the compressor.

How ejectors work
Ejectors work according to the Venturi principle. A high-pressure flow is accelerated through a nozzle, which leads to a drop in pressure. This pressure drop creates a vacuum, which makes it possible to attract a low-pressure flow (suction flow) that mixes with the high-pressure flow. The kinetic energy in the diffuser is then converted back into pressure energy, which leads to an increase in the pressure of the total mass flow.

Advantages
By recovering throttling losses, part of the compression work can be saved, which increases the overall energy efficiency of the heat pump

Ejectors can significantly reduce the required power of the compressor or even replace a compressor stage in multi-stage systems.

Ejectors allow adaptation to different operating conditions and can be used in different configurations to optimise performance.

Challenges
Despite their advantages, ejectors are not yet widely used in practice. Ejectors need to be precisely matched to their operating conditions, which places high demands on the design. Furthermore, uncertainty about the cost-benefit ratio is one reason why many manufacturers do not implement this technology.

Overall, ejectors offer promising opportunities for increasing efficiency in heat pump systems, but require further research and development in order to optimise their application in industry and make them economically attractive.

]]><![CDATA[HVAC Equipment Noise proofing and sensors]]>Tue, 10 Dec 2024 17:23:32 GMThttp://www.forcotech.com/blog/hvac-equipment-noise-proffing-and-sensorsNoise protection measures are an important issue today when planning larger heat pumps, VRF/VRV and refrigeration systems. This is due to denser construction, greater sensitivity of the population to the environment and therefore also to noise, and stricter regulatory requirements.

In many cases, this not only affects new systems, but also systems that are already in operation.

This is where modern acoustic arbours come in, which not only aim to reduce noise emissions, but are also equipped with appropriate sensor technology to enable better control of the systems, monitoring of energy efficiency and early detection of anomalies in system operation.

(1) /(2) Sensors for controlling the air inlet and outlet openings

Control of the position of the air inlet and outlet louvres of the acoustic bonnet to optimise the air flow. The louvres can be set to 4 different positions via sensors to control the air volume flow:
Closed louvres = example for cold start of a heat pump at low outside temperatures / 45° = normal operation of the system up to 50% air volume / 60° = normal operation of the system up to 80% air volume / 90° full load operation or ‘Free Cooling’ mode for refrigeration systems.

(3) Refrigerant sensors

Early detection of refrigerant losses and prevention of compressors running dry. Positioning of the sensors depending on the specific weight of the refrigerant. For systems with flammable refrigerant in combination with storm ventilation to prevent the accumulation of an ignitable quantity of refrigerant.

(4) Air pressure sensors

Air pressure sensors for measuring pressure losses and air velocity enable the systems to be optimised. The air velocity can also be optimised by combining this with controlling the position of the air inlet and outlet fins.

(5) Sensor technology Measurement of temperature, humidity and sound

Are a standard application in sensor technology. The air inlet temperature with the comparison of the temperature of the system's exhaust air is another way of identifying potential for optimising the systems.
In future, the recording of acoustics during normal operation of the system with the ongoing adjustment of the acoustics during operation of the systems will be a possibility for the early detection of system faults, even in the event of the smallest acoustic change.

(6) Sound insulation on the inside

StratocellWhisper-FR-400 mm

]]><![CDATA[continuously recording and analyzing noise and vibrations of HVAC Equipment]]>Fri, 26 Apr 2024 08:43:56 GMThttp://www.forcotech.com/blog/april-26th-2024The acoustics of systems can be an important indicator of the condition and performance of HVAC systems and machines in general. By , anomalies can be detected and potential problems identified at an early stage.

This method is referred to as “Acoustic Predictive Maintenance” and is an example of predictive maintenance that will replace “preventive maintenance” concepts in HVAC systems.

“Acoustic Predictive Maintenance” is a method based on the analysis of noise and vibrations. The continuously recorded machine noises are compared with the noise data from normal operation in order to derive statements about the operating status. Noise and vibration analysis is used to detect anomalies and identify potential problems at an early stage. The data is evaluated in real time and compared with the reference data. If deviations are detected, suitable measures can be taken to prevent or minimize damage.

By evaluating acoustic data in combination with information from air pressure, refrigerant, humidity and temperature sensors, HVAC systems can be monitored virtually seamlessly in real time, reducing unplanned downtime, extending the service life of systems and cutting maintenance costs.

]]><![CDATA[System maintenance and energy efficiency]]>Mon, 25 Dec 2023 09:48:59 GMThttp://www.forcotech.com/blog/anlagewartung-und-energieeffizienzEnergy-efficient refrigeration systems and heat pumps are not just a question of the latest compressors, fans or refrigerants; the issue stands and falls with the maintenance of the systems.

The picture below shows an evaporator of an industrial process cooling system where we have installed a sound enclosure. After removing the protective grilles in front of the evaporator, we found it to be completely dirty. Practically no air was passing through the evaporator fins and the system was constantly running at its limit in order to generate any cooling capacity at all. This not only has a negative effect on the cooling capacity, but also results in higher power consumption (current).

The picture next to it shows the evaporator after cleaning, with the evaporator fins once again air-permeable.

Important: the evaporator fins must be cleaned against the direction of air flow (blowing out). We must warn against mechanical cleaning with a broom or a high-pressure cleaner from the outside, as this only leads to the dirt accumulating between the fins and thus the dirt only being relocated.

]]><![CDATA[Acoustic bonnet for a dry cooler]]>Sun, 01 Oct 2023 06:51:54 GMThttp://www.forcotech.com/blog/schallhaube-fur-einen-ruckkuhlerInitial situation
As part of the refurbishment of the first floor of the Bubenberghaus on Schanzenstrasse in Bern, the cooling system is also being replaced and extended. The capacity of the cooling system was increased compared to the previous system, which meant that the precautionary noise values were not met. The recooler is used to cool the entire building, but in particular the MRI systems of the radiology centre located in the building. Noise emissions must be reduced by at least 14 dB(A). This is achieved by using the installed acoustic bonnet.

The recooler has the following dimensions: 7,646 x 2,420 x 2918 mm (L x W x H). The system has 12 EC fans. The total air volume of the system at full load is 220,000 m3/h.

Sound enclosure concept
The basic structure of the sound enclosure consists of 6 modules of an aluminium plug-in profile frame that are connected to each other in place. The service doors around the system were integrated into the profile frames. The inside of the doors is lined with 40 mm ‘StratocellWhisper’ insulation. The acoustic bonnet was built from 6 modules that were simply mounted on top of and next to each other and statically reinforced. The air chambers between the supply and exhaust air are hermetically separated by the use of separating panels that run in a rail system of aluminium U-profiles. The panels can be opened at some points so that access to the fans is possible at any time.

The assembled modules have the following dimensions:
9,446 x 4,100 x 3,618 mm (L x W x H) with a weight of 2,040 kg.

The air outlet speed at full load is around 10.2 metres/sec.

In terms of energy, it is interesting to compare the ambient air temperature with the temperature of the air entering the condenser. Despite the relatively high air inlet velocity, this is around 5.4° Celsius lower than the air temperature outside the bonnet.

The reason for this is obviously the shading of the condenser on all sides in combination with the movement of the air, which leads to this relatively high cooling of the air as it enters the condenser. This will also have a positive effect on the cooling capacity and power consumption of the dry cooler.

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