District Heating, Cooling and Energy Recovery By Frank Caul

Refrigeration, Heat Pump and Air systems have been in commercial use for over a hundred years now and used for a huge variety of purposes eg: Food Storage, human comfort, and production of a wide variety of goods in manufacturing processes. The relatively

recent commercialising of heat -pump technology has opened many new applications and uses. These applications have been somewhat limited by the maximum temperatures on the high side, being in the order of 50°C depending on working fluid (refrigerant) employed.

Go too high and Coefficient of performance is impacted. However still very useful in under floor heating systems or systems designed for low grade heat.

1 electrical Kw in will generally move 3 to 4 Kw of thermal energy from one place to another. So, with these machines, we can move energy into or out of a space or product. Heat pumps are now classified under part L as a renewable provided they meet minimum efficiency criteria which is relatively easily met , and are a positive contributor to meeting the Primary energy goal as a result of their ability to move 3 to 4 times their thermal energy Kw equivalent.

We are likely to see much more of this technology employed into the

future.

Thermal Balancing

Where we can match loads for heating and cooling such as in

De-humidification applications where simultaneous heating

and cooling is required then the COP will double to as much as 7/8 to 1.

ENERGY SYMPOSIUM 2017

There are many other applications that exist for example swimming pools where the heat extracted from the moist air in order to de

de-humidify the air is very often used to heat the pool water.

Many applications already existing in Ireland where heat pumps are used to both heat and cool , the issue of balancing the

load can be met by dumping heating water or coolant when a difference of load exist between heating and cooling demand

the excess can be dumped to an aquifer or even an air -cooled source.

Other areas are now opening up with higher Temperatures of up to 130°C possible using Co2 as a Refrigerant in a transcritical cycle. Now being employed in Japan where a million of these units are used for Domestic hot water production from air -source.

Heat pumps could alsobe used to extract waste heat from Data centres and feed into a district heating grid for example.

A data centre load of 10MW can heat close to 20,000 homes.

Some schemes to attract this type of business are providing free cooling to Data centres in exchange for the waste heat. If we are going to have Data centres let’s have them in our city’s where the waste energy can be usefully used. So what we need is planning foresight to design and build.  Cities and urban areas of high Density, high rise apartment schemes, Office blocks, public buildings, library, clean tech industry, Data centres, Smart Grid and connected buildings and systems.Use renewable energy combined with, Storage to include an electrical battery, and thermal, build heating and cooling capacity into each building and charge at nigh to help smooth out load. No car parks instead use the space for thermal

storage, obligatory connection to heat networks