Hybrid heat pump for industrial applications: experimental characterization and optimal configuration

How to turn solar heat and industrial waste heat into useful cooling effect? Industrial processes are often energy-intensive and the need for their efficient decarbonization is now at the forefront of governmental and corporate policies worldwide. However, solutions for the green transition of the industrial sector should be:

  • Flexible
  • Widely applicable
  • Reliable

And should:

  • Minimize energy consumption
  • Reduce operational costs
  • Lower CO2 footprint

Is there a solution to all these answers? Heat pumps are the fit match to tackle these issues.

Within HYCOOL, CNR ITAE and Fahrenheit have developed a hybrid thermal heat pump for application in several industrial sectors where efficient and sustainable cooling is needed. But what is the hybrid heat pump?

The hybrid heat pump concept

HYCOOL system proposes the combination of a thermal heat pump with an electrical heat pump: the thermal heat pump exploits low-temperature waste heat (i.e. 70-90 °C) that is generally unused or dumped to the ambient. It can also be powered by renewable sources, such as solar heat and biomass. The electrical heat pump can exploit electricity locally produced (i.e. from PV panels or other sources) and thus further increase the share of renewables. The hybridization consists in the configuration of the two heat pumps: they can work in series, in parallel or in cascade by just changing the hydraulic connections. This makes HYCOOL configuration flexible and easily adaptable to different industrial cases.

In the framework of HYCOOL, two case studies are considered, which are shown in Figure 1:

  • At GIVAUDAN (chemical industry), process cooling at +5°C is needed. To achieve this target with an overall high efficiency, the base load is covered with an adsorption unit (80 kW nominal power) that cools down the fluid in the range 5-21°C. Peak load is supplied by a compression unit with a natural refrigerant (propane, R290), that is connected in series with adsorption unit.
  • At Bodedebò (food industry), cooling of food at -10°C is needed. In this case, the efficiency in cooling generation is achieved by using a cascade configuration: the thermal heat pump (adsorption) is used as topping stage for the electrical heat pump, in a two-stage system. This increases the efficiency of the electrical heat pump up to 40% at the expenses of renewable or even waste low-grade heat, so virtually without the need for extra cost.
Figure 1: HYCOOL flexible configuration of the hybrid heat pump.

Experimental evaluation of the hybrid heat pump

The hybrid heat pump was tested in the laboratories of CNR ITAE in Messina in design and off-design conditions (see Figure 2). The aim of the tests was to define the cooling power and electricity consumption of the hybrid heat pump in the different ambient and process operating conditions, as well as confirm the reliability under off-design conditions. To this purpose, more than 100 testing cases were evaluated, and the results were reported in form of performance maps, like those in Figure 3.

Figure 2: the hybrid heat pump installed at CNR.
Figure 3: performance maps of the hybrid heat pump tested at CNR.

Is HYCOOL solution feasible for you?

HYCOOL solution is widely suitable for a vast range of processes. To know whether solar cooling can be part of your industrial processes, a screening tool, based on process requirements and information on the solar radiation in your industry’s location, was realized and is accessible here:

The results of the experimental testing at CNR, instead, were used to compile a calculator to predict the refrigeration capacity and energy efficiency ratio (EER) of the cascade HYCOOL chiller for a given industrial cooling process. You can access the tool here:

References

Written by CNR-ITAE

Start of the Works to Launch the Pilots

At the end of last September, the pilots of the HyCool project (Industrial Cooling through Hybrid system based on solar heat) began their way to start-up. In this initial phase of project execution, the two demonstration sites have started the civil works with which the necessary infrastructures are built to house the equipment and all parts of the system. These works are developed on the following fronts: 

  1. Givaudan: installation of the solar field on a plot adjacent to the plant; construction of a prefabricated technical room next to the solar field that will provide water vapor to the production plant from solar energy and with the technology supplied by Ecotherm; construction of the technical room that will supply cold to the plant, using adsorption pumps built by Fahrenheit.
     
Solar Field place at Givaudan pilot site
Slab for the Solar field Equipment Room (Ecotherm)
Construction of the Fahrenheit Equipment Room

2. Bo de Debó: installation of the solar field on one of the warehouses of the production plant; construction of the technical room that will house the hot and cold water production system using using Fahrenheit hybrid heat heat pumps and Ecotherm solar technology

Bo de Debó Technical Room works

The construction works are expected to be completed by the end of November 2020, giving way to the installation and commissioning stages of the HyCool systems, whose commissioning is expected in mid-June 2021. 

Industrial Cooling Based on Solar Heat at the Demo Sites

Article by Alex Grande, from IDP

Powering of industrial processes, if based on renewable technologies, may offer greater potential for CO2 emission reductions. Solar thermal energy is a promising sector which has been widely studied during the last two decades, becoming a candidate of the highest potential among renewable energy technologies, especially for industrial heating and cooling processes, because some technologies, such as heat pumps and mechanical vapour recompression, are particularly effective in hybrid systems.

The use of direct solar heat in industry is often hampered by barriers like lack of nearby available surface and seasonal imbalances. However, recent solar steam developments applied in the cooling demand services is growing worldwide with a wider variety of use, mainly within the industry. Some technologies, such as heat pumps are particularly effective. The two demonstration sites selected to tests Hycool system (Bo De Debó and Givaudan) are industries where custom-designed packages will be built, installed and tested.

Bo De Debó is a specialised industry in preparing precooked fresh dishes based on meat, fish and vegetable products, for being frozen, vacuum-packed or canned, and then sealed. In this site, Hycool will pre-cool the water in a buffer tank where it should be cooled down with other chiller in order to get 3-5ºC needed for the production of “gazpacho” (a kind of vegetables juice) and food washing processes. The residual heat from the system will be used to produce hot water for cleaning operations.

CSP-Panels to be installed in the roof of Plant 3, in Bo de Debo facilities in Sant Vicenç de Castellet

Givaudan is the global leader in the creation of flavours and fragrances. In close collaboration with food, beverage, consumer product and fragrance partners, Givaudan develops tastes and scents that delight consumers the world over. The Hycool system will provide the cold water needed to refrigerate the glycol stored in a buffer tank before it’s pumped to the vacuum pump water rings. The residual heat from the system will be used to produce steam to be injected in the factory net.

The old chilling system that will be substituted for the Hybrid Heat Pump from the new Hycool system, in Givaudan facilities (Sant Celoni – Spain).

In summary, the solar thermal energy provided by the Hycool System will allow our pilot sites:

  • To reduce their productions costs by using a free source of energy
  • To increase their system efficiency by using the residual thermal energy for producing heat water or steam
  • To reduce their global CO2 emissions by reducing the use of fossil fuels for producing that heat

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