Table 1 Nomenclature energy concept
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 |
COPhp | 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 |
Ï• biogas, Ï• 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) |