Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Urban water networks as an alternative source for district heating and
  emergency heat-wave cooling   Urban water networks can contribute to the energy transition of cities by
serving as alternatives sources for heating and cooling. Indeed, the thermal
energy potential of the urban water cycle is considerable. Paris is taken as an
example to present an assessment of the field performance of a district-scale
waste water heat recovery system and to explore potential techniques for
emergency cold recovery from drinking or non-potable water networks in response
to heat-waves. The case heat recovery system was found to provide significant
greenhouse gas emission reductions (up to 75%) and limited primary energy
savings (around 30%). These limited savings are found to be mainly due to the
performance of the heat pump system. Three emergency cold recovery techniques
are presented as a response to heat-waves: subway station cooling, ice
production for individual cooling, and "heat-wave shelter" cooling in
association with pavement-watering. The cold generation potential of each
approach is assessed with a special consideration for mains water temperature
sanitary limitations. Finally, technical obstacles and perspectives are
discussed.

23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol