Ice storage, heat pumps & solutions from aquatherm __

Ice storage, heat pumps & solutions from aquatherm
19. September 2024 6 min.

At first glance, the combination of ice storage and a heat pump may seem contradictory. However, this synergy offers a highly efficient, economical, and sustainable solution for the heating of buildings, as well as for air conditioning and cooling – which is becoming increasingly important due to more frequent extreme weather and hotter summers. aquatherm provides the corrosion-free aquatherm blue plastic pipe system for connecting ice storage tanks to heat pumps and for piping the hydraulic modules. The highly efficient aquatherm black is used for surface heating and cooling. Additionally, the insulated aquatherm energy pipe system is available for longer distances from the ice storage tank to the heat pump.

The principle of an ice storage tank in combination with a heat pump is based on the use of the latent thermal energy that is released during the phase transition from water to ice. The intelligent combination of different technologies creates a system that is both energy-efficient and environmentally friendly. These systems are an attractive option not only for large commercial buildings but also for private residences, helping to reduce heating costs and improve sustainability in the long term.

 

Advantages of ice storage for large buildings

Whether for office complexes, residential buildings, production facilities, or public institutions, ice storage or ice energy storage systems offer outstanding efficiency in large buildings. This technology is especially beneficial for structures with high heating and cooling demands, as it allows for a significant reduction in peak loads by storing excess energy for later use. This peak-shaving capability leads to more consistent and optimised energy use. When combined with heat pumps, ice storage is one of the most sustainable solutions for buildings with high energy requirements. It not only helps to minimise energy consumption but also stores surplus energy from renewable sources, such as photovoltaics, and releases it when needed.

 

Advantages for residential spaces

The ice storage tank also stands out in the private sector due to its high efficiency. By utilising latent thermal energy, operating costs can be greatly reduced compared to traditional heating systems. The flexibility in sizing the ice storage system allows it to be tailored precisely to the needs of a household, making it suitable for a range of living situations, from single-family homes to apartment buildings.

 

Components and functionality of the ice storage system in combination with heat pumps

Ice storage

The central thermal storage comprises an underground water tank that captures and stores the thermal energy generated during the phase change from water to ice. This storage system serves as the core of the setup, facilitating the efficient use of latent heat for both heating and cooling processes.

Brine heat pump

The brine heat pump selectively extracts heat and cold from the water in the ice storage tank and transfers it to a surface heating and cooling system within the building. Utilising the heat of crystallisation, the heat pump operates with high efficiency and helps to lower energy consumption.

Surface heating and cooling

Systems like aquatherm black use the heat and cold delivered by the heat pump in the low-temperature range. These panel heaters can both heat and passively cool the building, making them especially versatile. Ideally, this is done through the ceiling.

Solar collectors

These components gather solar heat and help regenerate the ice reservoir by melting the frozen water. This prepares the system for the next heating cycle and maximizes the use of solar energy.

Photovoltaic

As an optional extension, a photovoltaic system can support the operation of the heat pump with renewable energy. This increases the overall efficiency of the system and minimises the carbon footprint.

 

The processes of an ice storage system

Latent heat / heat of crystallisation

When water freezes into ice, it releases a substantial amount of thermal energy, referred to as the heat of crystallisation. This energy can be harnessed by the heat pump to heat the building. The latent heat released is approximately equal to the energy needed to heat water from 0 °C to 80 °C.

Freezing process

The heat pump works by extracting heat from the water in the ice tank using a heat exchanger. This exchanger absorbs the thermal energy and transfers it to the building's heating system. As heat is removed from the ice storage tank, the water temperature drops. When it reaches the freezing point, the water begins to freeze into ice.

Regeneration of ice storage

To regenerate the ice storage and melt the ice, external heat sources such as solar collectors, air heat, or waste heat can be used. These heat sources provide the necessary energy to melt the ice in the storage tank back into water, so the storage system is ready for the next heating cycle.

Heating and cooling mode

In heating mode, the heat pump extracts the stored thermal energy from the ice storage tank to heat the building efficiently. In cooling mode, the system works in reverse, using the cold stored in the ice storage tank to cool the building. This dual functionality allows the ice storage system to be used throughout the year, providing both heating and air conditioning in a sustainable and energy-efficient way.

Ice storage
Ice storage
Ice storage
Ice storage
Ice storage
Ice storage

 

Why aquatherm PP pipe systems are particularly suitable for ice storage and heat pumps

aquatherm blue for connecting heating systems

aquatherm blue, made from Polypropylene (PP), is designed for transporting cooling and heating media in closed systems. The unique physical properties of this plastic are tailored to meet the requirements of the heating and cooling sector. The material’s corrosion resistance extends the service life of heating systems. Additionally, aquatherm blue has heat and sound insulating properties, which reduce the need for additional heat and cold insulation compared to metallic pipes and lessen the requirement for condensation insulation.

aquatherm black for surface heating and surface cooling

aquatherm black is specially designed for use in surface heating and cooling systems for ceilings, walls, and floors. They can also serve as solar air absorbers, efficiently harnessing solar energy and converting it into thermal energy. Whether used for heating/cooling systems or as solar air collectors, aquatherm black is ideal for integration with ice storage and heat pumps. It is particularly well-suited for low-temperature systems like heat pumps, operating efficiently with flow temperatures ranging from 25° to 35°C. This results in substantial energy savings, with potential reductions in energy costs of up to 25% to 30%. Additionally, the reduced air movement minimises house dust turbulence, contributing to a healthier indoor climate.

 

Material advantages of aquatherm PP pipe systems compared to metal pipes

The pipe materials of aquatherm blue, made from fusiolen® PP-RCT (from an outer diameter of 32 mm), and aquatherm black, made from fusiolen® PP-R, offer excellent ecological properties as well as high temperature and pressure resistance. They are durable and resistant to chemical influences. aquatherm plastic pipes provide several specific advantages compared to other materials such as metal:

Corrosion resistance

In contrast to metal pipes, which are susceptible to corrosion, aquatherm plastic pipes are corrosion resistant.

Easy installation

Plastic pipes are lighter than metal pipes, making them easier to handle and install. This leads to reduced labour costs and quicker installation.

Heat fusion technology

The connection of the pipes is done by heat fusion, which ensures a strong, durable, and leak-free connection. This reduces the need for frequent maintenance and repairs compared to metal pipes.

Sustainability

For aquatherm plastic pipe systems, an Environmental Product Declaration (EPD) and other certificates are available, documenting their environmentally friendly properties and sustainable production.

Less CO₂ footprint

Manufacturing and recycling plastic pipes have a lower carbon footprint compared to metal pipes, which require significant energy for melting down.

Recyclability

Polypropylene is an easily recyclable material, which further reduces the environmental impact.

Low thermal conductivity

aquatherm pipes have a lower thermal conductivity than metal pipes. The minimised heat losses are particularly advantageous in heating and cooling systems.

No Incrustation

No deposits form that can lead to pipe blockages, pressure increases, and leaks.

Noise attenuation

aquatherm pipes are quieter than metal pipes because they absorb noise more effectively. This is a significant advantage for noise reduction in buildings where people are continuously present, such as residential and office buildings.

 

References for ice storage and heat pumps with aquatherm

The references illustrate the versatility and efficiency of ice storage heat pump systems in combination with aquatherm black and aquatherm blue in different areas of application. The projects show how innovative heating and cooling solutions can be successfully implemented.

Event location "2T"

The climbing and bouldering hall "2T" in Lindlar (Germany) presented a particular challenge for energy-efficient heating and cooling due to its size and historic buildings. The innovative energy concept is based on an ice storage tank with a capacity of 1,700 cubic metres of water. Together with a heat pump, it supplies the heating and cooling energy for the halls. The supply lines to the ice storage tank and all piping in the technical centre were implemented with the aquatherm blue pipe system. aquatherm black is used for heating and cooling the hall itself, ensuring an even temperature distribution in the upper wall areas.

dekoGraphics

At the new headquarters of dekoGraphics in St. Leon-Rot (Germany), the focus was on meeting the primary energy demand entirely with renewable sources. The solution was a sophisticated energy concept that combines an ice storage heat pump with a power roof – featuring a photovoltaic system and a charger system. aquatherm black, installed as a solar-air absorber on the flat roof, plays a key role in this system. It utilises both ambient heat and solar radiation to generate heat for the heat pump and regenerate the ice storage tank. Additionally, aquatherm black helps cool the photovoltaic system, increasing the efficiency of power generation. This innovative combination of technologies enables the building to meet its energy requirements sustainably and efficiently, while significantly reducing CO₂ emissions.

dekoGraphics

 

The logistics hall Distribo

For the new Distribo logistics hall in Göttingen, Germany, it was essential to significantly reduce energy consumption despite high heating and cooling demands. In collaboration with various partners, a customised air conditioning concept was developed, incorporating ice storage systems, heat pumps, and aquatherm systems. aquatherm blue was integral to this, handling the piping for the hydraulic modules and connecting them to the ice accumulator. aquatherm energy, with its PUR foam insulation and HDPE sheathing, was used for long-distance pipelines, minimising energy losses. This integrated system allows the logistics hall to maintain consistent temperatures while markedly reducing energy consumption compared to conventional systems.

Logistic hall Distribo
Logistic hall Distribo

 

Result

The ice storage/heat pump concept, combined with the comprehensive solution of the aquatherm blue and aquatherm black pipe systems, offers a highly efficient option for sustainably heating and cooling modern buildings. By utilising latent thermal energy during the water-to-ice phase change, it efficiently manages heating and cooling loads, resulting in significant energy cost savings for both commercial and residential applications. This system is particularly effective in large buildings with high heating and cooling demands, as it smooths peak loads and ensures even energy distribution.

 

Surface heating and cooling systems

Find out about current potential, technologies and efficient application solutions.

 

Download: Article