Question: Allocation Memory Problems

Hi everyone, here we are again with more serius issues this time.

I have a system of DE to solve. My system is made of coupled 3 PDE`s with 1 ODE. My problem is that the computation is aborted due failure at memory allocation, here is the message:

"Error, (in factor/nexteval) Cannot Allocate Memory (size=151060480)"

I`ve checked the kernelopts about datalimit and its already infinity. My computer is a Turion x2 with 4Gb of Ram (system of 32bits so the usage of RAM is 3.37)

But here in my laboratory i`ve got a I7 with 16Gb, same problem.

Is there any routine or command to expand maples` software capacity of allocating memory?

Here is my code:

PDEsys:={diff(Cf(z,t),t)+vf*(diff(Cf(z,t),z))=k*a*(Csat-Cf(z,t)),                 (1)
              ros*(diff(Es(z,t),t)+vs(z,t)*(diff(Es(z,t),z)=-k*a*(Csat-Cf(z,t)),    (2)
              diff(vs(z,t),t)=Fr*Np/(ros*Es(z,t))                                              (3)
              diff(T(z,t),t)+vf*diff(T(z,t),z)=-(Q1-Q2)/(Aesc*L*rol*cp)}            (4)

Where
(1)- is the global mass balance for the liquid phase
(2)- is the global mass balance for the solid phase
(3)- is the momentum balance for the avarage particle
(4)- is the global energy balance for the liquid phase admiting equilibrium between liquid and solid phase.

The dependent variables are Cf,Es,vs and T

The independent variables are somewhat complex, being like this:

k is a function of T(z,t)
a is a funtion of Es(z,t)
rol is a function of Cf(z,t)
...

Most of the independent variables contains mathematical relations involving the dependent variables, that`s why I guess the computation is becoming to heavy.

Any suggestions on how I solve this puzzle?

Thanks in advance

Sergio.