Secondary fluids for food refrigeration and cold stock induce to an important decrease on electric power consumption and an increase on the power demands curve during a day. Using nanofluids for heat exchange leads to important benefits including increasing to the thermal conductivity, density and specific heat in some cases, impacting directly on heat transport efficiency which implies in reducing both, size equipment and time for cooling process. In this work, nanofluids with different multiwalled carbon nanotubes (MWCNT) concentrations in water and in propilenglycol solution (50 wt%) were produced and evaluated in their stability by measuring the potential zeta and mean size by using triton X-100 and arabic gum as surfactants and functionalized carbon nanotubes (COOH-MWCNT). The simulation of a heat transfer circuit exposing the nanofluids at 90°C and shaking it at 4100 rpm shows that arabic gum lead to a better stability and thermal conductivity augmentation than triton X-100, samples of COOH-MWCNT presents major thermal conductivity augmentation and the less viscosity augmentation for both fluids, but for water suspensions COOH-MWCNT presents less stability for concentrations greater than 0,5 wt%. Thermal conductivity acquires major augmentation in temperatures between 40°C and 50°C presenting about 15%, 10% and 8% of augmentation for COOH-MWCNT, A.G-MWCNT and TrX100_MWCNT respectively at 1 wt% in water, otherwise nanofluids of propylenglycol solutions presents no substantial variation with temperature, showing augmentations about 6 % and 7 % for MWCNT and COOHMWCNT respectively with 1 wt%. Results indicate that small concentrations of MWCNT cause substantial changes on thermal conductivity but high concentrations increases more viscosity than thermo conductivity. Values of specific heat and density of the nanofluid are larger than the original fluid too, considering the effect of solid particles suspending into the fluid which may contribute to the turbulence during pumping.