From: Upscaling a district heating system based on biogas cogeneration and heat pumps
Term | Signification |
---|---|
η _{chp,e }, η _{chp,t } | CHP electric and thermal efficiency |
η _{ b,t } | Boiler thermal efficiency |
η _{sto,ht} | High temperature (HT) thermal storage average efficiency |
η _{sto,lt} | Low temperature (LT) thermal storage average efficiency |
η _{distr} | DH distribution network average efficiency |
COP_{hp} | Heat pump (HP) coefficient of performance (COP) |
COP_{ c } | Refrigeration chiller COP |
f _{netw,p } | Fraction of required electric pump energy for network pumps related to transmitted thermal energy of the network |
ϕ _{biogas}, ϕ _{ngas} | Biogas supply to CHP, natural gas supply to boilers (m ^{3}/h) |
LHV | Lower heating value (MJ/m ^{3}) |
\(\dot {Q}_{\text {biogas}}\) or \(\dot {Q}_{\text {ngas}}\) | Fuel-related thermal energy input (kW) |
Q _{dh,demand,h } | Total DH heating demand of (n) connected houses (GJ) |
Q _{hp,demand,h } | Total heating energy demand of (m) houses with a heat pump (GJ) |
Q _{hp,source} | Total low temperature source heat for the heat pumps (GJ) |
Q _{dhw}, Q _{sh} | Domestic hot water demand and space heating demand (GJ) |
Q _{demand,c }, Q _{dh,c }, Q _{hp,c } | Cooling energy demand, for DH network houses, for houses with heat pumps (GJ) |
\(\dot {E}_{\text {chp}}\) | CHP electric rated power (kW) |
\(\dot {Q}_{\text {chp}}\) | CHP thermal rated power (kW) |
\(\dot {Q}_{b}\) | Boiler thermal rated power (kW) |
t _{op,chp} and t _{op,b } | Full load operational hours of the CHP and boiler (h/year) |
\(\dot {E}_{c}\), \(\dot {Q}_{c}\) | Refrigeration chiller electric rated power and cooling rate (kW) |